/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema/SemaLookup.cpp

Bug Summary

File:	clang/lib/Sema/SemaLookup.cpp
Warning:	line 1168, column 43 Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name SemaLookup.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema/SemaLookup.cpp

/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema/SemaLookup.cpp

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1//===--------------------- SemaLookup.cpp - Name Lookup  ------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file implements name lookup for C, C++, Objective-C, and
10//  Objective-C++.
11//
12//===----------------------------------------------------------------------===//

14#include "clang/AST/ASTContext.h"
15#include "clang/AST/CXXInheritance.h"
16#include "clang/AST/Decl.h"
17#include "clang/AST/DeclCXX.h"
18#include "clang/AST/DeclLookups.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/DeclTemplate.h"
21#include "clang/AST/Expr.h"
22#include "clang/AST/ExprCXX.h"
23#include "clang/Basic/Builtins.h"
24#include "clang/Basic/FileManager.h"
25#include "clang/Basic/LangOptions.h"
26#include "clang/Lex/HeaderSearch.h"
27#include "clang/Lex/ModuleLoader.h"
28#include "clang/Lex/Preprocessor.h"
29#include "clang/Sema/DeclSpec.h"
30#include "clang/Sema/Lookup.h"
31#include "clang/Sema/Overload.h"
32#include "clang/Sema/Scope.h"
33#include "clang/Sema/ScopeInfo.h"
34#include "clang/Sema/Sema.h"
35#include "clang/Sema/SemaInternal.h"
36#include "clang/Sema/TemplateDeduction.h"
37#include "clang/Sema/TypoCorrection.h"
38#include "llvm/ADT/STLExtras.h"
39#include "llvm/ADT/SmallPtrSet.h"
40#include "llvm/ADT/TinyPtrVector.h"
41#include "llvm/ADT/edit_distance.h"
42#include "llvm/Support/ErrorHandling.h"
43#include <algorithm>
44#include <iterator>
45#include <list>
46#include <set>
47#include <utility>
48#include <vector>

50#include "OpenCLBuiltins.inc"

52using namespace clang;
53using namespace sema;

55namespace {
class UnqualUsingEntry {
  const DeclContext *Nominated;
  const DeclContext *CommonAncestor;

public:
  UnqualUsingEntry(const DeclContext *Nominated,
                   const DeclContext *CommonAncestor)
    : Nominated(Nominated), CommonAncestor(CommonAncestor) {
  }

  const DeclContext *getCommonAncestor() const {
    return CommonAncestor;
  }

  const DeclContext *getNominatedNamespace() const {
    return Nominated;
  }

  // Sort by the pointer value of the common ancestor.
  struct Comparator {
    bool operator()(const UnqualUsingEntry &L, const UnqualUsingEntry &R) {
      return L.getCommonAncestor() < R.getCommonAncestor();
    }

    bool operator()(const UnqualUsingEntry &E, const DeclContext *DC) {
      return E.getCommonAncestor() < DC;
    }

    bool operator()(const DeclContext *DC, const UnqualUsingEntry &E) {
      return DC < E.getCommonAncestor();
    }
  };
};

/// A collection of using directives, as used by C++ unqualified
/// lookup.
class UnqualUsingDirectiveSet {
  Sema &SemaRef;

  typedef SmallVector<UnqualUsingEntry, 8> ListTy;

  ListTy list;
  llvm::SmallPtrSet<DeclContext*, 8> visited;

public:
  UnqualUsingDirectiveSet(Sema &SemaRef) : SemaRef(SemaRef) {}

  void visitScopeChain(Scope *S, Scope *InnermostFileScope) {
    // C++ [namespace.udir]p1:
    //   During unqualified name lookup, the names appear as if they
    //   were declared in the nearest enclosing namespace which contains
    //   both the using-directive and the nominated namespace.
    DeclContext *InnermostFileDC = InnermostFileScope->getEntity();
    assert(InnermostFileDC && InnermostFileDC->isFileContext())(static_cast<void> (0));

    for (; S; S = S->getParent()) {
      // C++ [namespace.udir]p1:
      //   A using-directive shall not appear in class scope, but may
      //   appear in namespace scope or in block scope.
      DeclContext *Ctx = S->getEntity();
      if (Ctx && Ctx->isFileContext()) {
        visit(Ctx, Ctx);
      } else if (!Ctx || Ctx->isFunctionOrMethod()) {
        for (auto *I : S->using_directives())
          if (SemaRef.isVisible(I))
            visit(I, InnermostFileDC);
      }
    }
  }

  // Visits a context and collect all of its using directives
  // recursively.  Treats all using directives as if they were
  // declared in the context.
  //
  // A given context is only every visited once, so it is important
  // that contexts be visited from the inside out in order to get
  // the effective DCs right.
  void visit(DeclContext *DC, DeclContext *EffectiveDC) {
    if (!visited.insert(DC).second)
      return;

    addUsingDirectives(DC, EffectiveDC);
  }

  // Visits a using directive and collects all of its using
  // directives recursively.  Treats all using directives as if they
  // were declared in the effective DC.
  void visit(UsingDirectiveDecl *UD, DeclContext *EffectiveDC) {
    DeclContext *NS = UD->getNominatedNamespace();
    if (!visited.insert(NS).second)
      return;

    addUsingDirective(UD, EffectiveDC);
    addUsingDirectives(NS, EffectiveDC);
  }

  // Adds all the using directives in a context (and those nominated
  // by its using directives, transitively) as if they appeared in
  // the given effective context.
  void addUsingDirectives(DeclContext *DC, DeclContext *EffectiveDC) {
    SmallVector<DeclContext*, 4> queue;
    while (true) {
      for (auto UD : DC->using_directives()) {
        DeclContext *NS = UD->getNominatedNamespace();
        if (SemaRef.isVisible(UD) && visited.insert(NS).second) {
          addUsingDirective(UD, EffectiveDC);
          queue.push_back(NS);
        }
      }

      if (queue.empty())
        return;

      DC = queue.pop_back_val();
    }
  }

  // Add a using directive as if it had been declared in the given
  // context.  This helps implement C++ [namespace.udir]p3:
  //   The using-directive is transitive: if a scope contains a
  //   using-directive that nominates a second namespace that itself
  //   contains using-directives, the effect is as if the
  //   using-directives from the second namespace also appeared in
  //   the first.
  void addUsingDirective(UsingDirectiveDecl *UD, DeclContext *EffectiveDC) {
    // Find the common ancestor between the effective context and
    // the nominated namespace.
    DeclContext *Common = UD->getNominatedNamespace();
    while (!Common->Encloses(EffectiveDC))
      Common = Common->getParent();
    Common = Common->getPrimaryContext();

    list.push_back(UnqualUsingEntry(UD->getNominatedNamespace(), Common));
  }

  void done() { llvm::sort(list, UnqualUsingEntry::Comparator()); }

  typedef ListTy::const_iterator const_iterator;

  const_iterator begin() const { return list.begin(); }
  const_iterator end() const { return list.end(); }

  llvm::iterator_range<const_iterator>
  getNamespacesFor(DeclContext *DC) const {
    return llvm::make_range(std::equal_range(begin(), end(),
                                             DC->getPrimaryContext(),
                                             UnqualUsingEntry::Comparator()));
  }
};
205} // end anonymous namespace

207// Retrieve the set of identifier namespaces that correspond to a
208// specific kind of name lookup.
209static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
                             bool CPlusPlus,
                             bool Redeclaration) {
unsigned IDNS = 0;
switch (NameKind) {
case Sema::LookupObjCImplicitSelfParam:
case Sema::LookupOrdinaryName:
case Sema::LookupRedeclarationWithLinkage:
case Sema::LookupLocalFriendName:
case Sema::LookupDestructorName:
  IDNS = Decl::IDNS_Ordinary;
  if (CPlusPlus) {
    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member | Decl::IDNS_Namespace;
    if (Redeclaration)
      IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
  }
  if (Redeclaration)
    IDNS |= Decl::IDNS_LocalExtern;
  break;

case Sema::LookupOperatorName:
  // Operator lookup is its own crazy thing;  it is not the same
  // as (e.g.) looking up an operator name for redeclaration.
  assert(!Redeclaration && "cannot do redeclaration operator lookup")(static_cast<void> (0));
  IDNS = Decl::IDNS_NonMemberOperator;
  break;

case Sema::LookupTagName:
  if (CPlusPlus) {
    IDNS = Decl::IDNS_Type;

    // When looking for a redeclaration of a tag name, we add:
    // 1) TagFriend to find undeclared friend decls
    // 2) Namespace because they can't "overload" with tag decls.
    // 3) Tag because it includes class templates, which can't
    //    "overload" with tag decls.
    if (Redeclaration)
      IDNS |= Decl::IDNS_Tag | Decl::IDNS_TagFriend | Decl::IDNS_Namespace;
  } else {
    IDNS = Decl::IDNS_Tag;
  }
  break;

case Sema::LookupLabel:
  IDNS = Decl::IDNS_Label;
  break;

case Sema::LookupMemberName:
  IDNS = Decl::IDNS_Member;
  if (CPlusPlus)
    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Ordinary;
  break;

case Sema::LookupNestedNameSpecifierName:
  IDNS = Decl::IDNS_Type | Decl::IDNS_Namespace;
  break;

case Sema::LookupNamespaceName:
  IDNS = Decl::IDNS_Namespace;
  break;

case Sema::LookupUsingDeclName:
  assert(Redeclaration && "should only be used for redecl lookup")(static_cast<void> (0));
  IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member |
         Decl::IDNS_Using | Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend |
         Decl::IDNS_LocalExtern;
  break;

case Sema::LookupObjCProtocolName:
  IDNS = Decl::IDNS_ObjCProtocol;
  break;

case Sema::LookupOMPReductionName:
  IDNS = Decl::IDNS_OMPReduction;
  break;

case Sema::LookupOMPMapperName:
  IDNS = Decl::IDNS_OMPMapper;
  break;

case Sema::LookupAnyName:
  IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member
    | Decl::IDNS_Using | Decl::IDNS_Namespace | Decl::IDNS_ObjCProtocol
    | Decl::IDNS_Type;
  break;
}
return IDNS;
296}

298void LookupResult::configure() {
IDNS = getIDNS(LookupKind, getSema().getLangOpts().CPlusPlus,
               isForRedeclaration());

// If we're looking for one of the allocation or deallocation
// operators, make sure that the implicitly-declared new and delete
// operators can be found.
switch (NameInfo.getName().getCXXOverloadedOperator()) {
case OO_New:
case OO_Delete:
case OO_Array_New:
case OO_Array_Delete:
  getSema().DeclareGlobalNewDelete();
  break;

default:
  break;
}

// Compiler builtins are always visible, regardless of where they end
// up being declared.
if (IdentifierInfo *Id = NameInfo.getName().getAsIdentifierInfo()) {
  if (unsigned BuiltinID = Id->getBuiltinID()) {
    if (!getSema().Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
      AllowHidden = true;
  }
}
325}

327bool LookupResult::sanity() const {
// This function is never called by NDEBUG builds.
assert(ResultKind != NotFound || Decls.size() == 0)(static_cast<void> (0));
assert(ResultKind != Found || Decls.size() == 1)(static_cast<void> (0));
assert(ResultKind != FoundOverloaded || Decls.size() > 1 ||(static_cast<void> (0))
       (Decls.size() == 1 &&(static_cast<void> (0))
        isa<FunctionTemplateDecl>((*begin())->getUnderlyingDecl())))(static_cast<void> (0));
assert(ResultKind != FoundUnresolvedValue || sanityCheckUnresolved())(static_cast<void> (0));
assert(ResultKind != Ambiguous || Decls.size() > 1 ||(static_cast<void> (0))
       (Decls.size() == 1 && (Ambiguity == AmbiguousBaseSubobjects ||(static_cast<void> (0))
                              Ambiguity == AmbiguousBaseSubobjectTypes)))(static_cast<void> (0));
assert((Paths != nullptr) == (ResultKind == Ambiguous &&(static_cast<void> (0))
                              (Ambiguity == AmbiguousBaseSubobjectTypes ||(static_cast<void> (0))
                               Ambiguity == AmbiguousBaseSubobjects)))(static_cast<void> (0));
return true;
342}

344// Necessary because CXXBasePaths is not complete in Sema.h
345void LookupResult::deletePaths(CXXBasePaths *Paths) {
delete Paths;
347}

349/// Get a representative context for a declaration such that two declarations
350/// will have the same context if they were found within the same scope.
351static DeclContext *getContextForScopeMatching(Decl *D) {
// For function-local declarations, use that function as the context. This
// doesn't account for scopes within the function; the caller must deal with
// those.
DeclContext *DC = D->getLexicalDeclContext();
if (DC->isFunctionOrMethod())
  return DC;

// Otherwise, look at the semantic context of the declaration. The
// declaration must have been found there.
return D->getDeclContext()->getRedeclContext();
362}

364/// Determine whether \p D is a better lookup result than \p Existing,
365/// given that they declare the same entity.
366static bool isPreferredLookupResult(Sema &S, Sema::LookupNameKind Kind,
                                  NamedDecl *D, NamedDecl *Existing) {
// When looking up redeclarations of a using declaration, prefer a using
// shadow declaration over any other declaration of the same entity.
if (Kind == Sema::LookupUsingDeclName && isa<UsingShadowDecl>(D) &&
    !isa<UsingShadowDecl>(Existing))
  return true;

auto *DUnderlying = D->getUnderlyingDecl();
auto *EUnderlying = Existing->getUnderlyingDecl();

// If they have different underlying declarations, prefer a typedef over the
// original type (this happens when two type declarations denote the same
// type), per a generous reading of C++ [dcl.typedef]p3 and p4. The typedef
// might carry additional semantic information, such as an alignment override.
// However, per C++ [dcl.typedef]p5, when looking up a tag name, prefer a tag
// declaration over a typedef. Also prefer a tag over a typedef for
// destructor name lookup because in some contexts we only accept a
// class-name in a destructor declaration.
if (DUnderlying->getCanonicalDecl() != EUnderlying->getCanonicalDecl()) {
  assert(isa<TypeDecl>(DUnderlying) && isa<TypeDecl>(EUnderlying))(static_cast<void> (0));
  bool HaveTag = isa<TagDecl>(EUnderlying);
  bool WantTag =
      Kind == Sema::LookupTagName || Kind == Sema::LookupDestructorName;
  return HaveTag != WantTag;
}

// Pick the function with more default arguments.
// FIXME: In the presence of ambiguous default arguments, we should keep both,
//        so we can diagnose the ambiguity if the default argument is needed.
//        See C++ [over.match.best]p3.
if (auto *DFD = dyn_cast<FunctionDecl>(DUnderlying)) {
  auto *EFD = cast<FunctionDecl>(EUnderlying);
  unsigned DMin = DFD->getMinRequiredArguments();
  unsigned EMin = EFD->getMinRequiredArguments();
  // If D has more default arguments, it is preferred.
  if (DMin != EMin)
    return DMin < EMin;
  // FIXME: When we track visibility for default function arguments, check
  // that we pick the declaration with more visible default arguments.
}

// Pick the template with more default template arguments.
if (auto *DTD = dyn_cast<TemplateDecl>(DUnderlying)) {
  auto *ETD = cast<TemplateDecl>(EUnderlying);
  unsigned DMin = DTD->getTemplateParameters()->getMinRequiredArguments();
  unsigned EMin = ETD->getTemplateParameters()->getMinRequiredArguments();
  // If D has more default arguments, it is preferred. Note that default
  // arguments (and their visibility) is monotonically increasing across the
  // redeclaration chain, so this is a quick proxy for "is more recent".
  if (DMin != EMin)
    return DMin < EMin;
  // If D has more *visible* default arguments, it is preferred. Note, an
  // earlier default argument being visible does not imply that a later
  // default argument is visible, so we can't just check the first one.
  for (unsigned I = DMin, N = DTD->getTemplateParameters()->size();
      I != N; ++I) {
    if (!S.hasVisibleDefaultArgument(
            ETD->getTemplateParameters()->getParam(I)) &&
        S.hasVisibleDefaultArgument(
            DTD->getTemplateParameters()->getParam(I)))
      return true;
  }
}

// VarDecl can have incomplete array types, prefer the one with more complete
// array type.
if (VarDecl *DVD = dyn_cast<VarDecl>(DUnderlying)) {
  VarDecl *EVD = cast<VarDecl>(EUnderlying);
  if (EVD->getType()->isIncompleteType() &&
      !DVD->getType()->isIncompleteType()) {
    // Prefer the decl with a more complete type if visible.
    return S.isVisible(DVD);
  }
  return false; // Avoid picking up a newer decl, just because it was newer.
}

// For most kinds of declaration, it doesn't really matter which one we pick.
if (!isa<FunctionDecl>(DUnderlying) && !isa<VarDecl>(DUnderlying)) {
  // If the existing declaration is hidden, prefer the new one. Otherwise,
  // keep what we've got.
  return !S.isVisible(Existing);
}

// Pick the newer declaration; it might have a more precise type.
for (Decl *Prev = DUnderlying->getPreviousDecl(); Prev;
     Prev = Prev->getPreviousDecl())
  if (Prev == EUnderlying)
    return true;
return false;
456}

458/// Determine whether \p D can hide a tag declaration.
459static bool canHideTag(NamedDecl *D) {
// C++ [basic.scope.declarative]p4:
//   Given a set of declarations in a single declarative region [...]
//   exactly one declaration shall declare a class name or enumeration name
//   that is not a typedef name and the other declarations shall all refer to
//   the same variable, non-static data member, or enumerator, or all refer
//   to functions and function templates; in this case the class name or
//   enumeration name is hidden.
// C++ [basic.scope.hiding]p2:
//   A class name or enumeration name can be hidden by the name of a
//   variable, data member, function, or enumerator declared in the same
//   scope.
// An UnresolvedUsingValueDecl always instantiates to one of these.
D = D->getUnderlyingDecl();
return isa<VarDecl>(D) || isa<EnumConstantDecl>(D) || isa<FunctionDecl>(D) ||
       isa<FunctionTemplateDecl>(D) || isa<FieldDecl>(D) ||
       isa<UnresolvedUsingValueDecl>(D);
476}

478/// Resolves the result kind of this lookup.
479void LookupResult::resolveKind() {
unsigned N = Decls.size();

// Fast case: no possible ambiguity.
if (N == 0) {
  assert(ResultKind == NotFound ||(static_cast<void> (0))
         ResultKind == NotFoundInCurrentInstantiation)(static_cast<void> (0));
  return;
}

// If there's a single decl, we need to examine it to decide what
// kind of lookup this is.
if (N == 1) {
  NamedDecl *D = (*Decls.begin())->getUnderlyingDecl();
  if (isa<FunctionTemplateDecl>(D))
    ResultKind = FoundOverloaded;
  else if (isa<UnresolvedUsingValueDecl>(D))
    ResultKind = FoundUnresolvedValue;
  return;
}

// Don't do any extra resolution if we've already resolved as ambiguous.
if (ResultKind == Ambiguous) return;

llvm::SmallDenseMap<NamedDecl*, unsigned, 16> Unique;
llvm::SmallDenseMap<QualType, unsigned, 16> UniqueTypes;

bool Ambiguous = false;
bool HasTag = false, HasFunction = false;
bool HasFunctionTemplate = false, HasUnresolved = false;
NamedDecl *HasNonFunction = nullptr;

llvm::SmallVector<NamedDecl*, 4> EquivalentNonFunctions;

unsigned UniqueTagIndex = 0;

unsigned I = 0;
while (I < N) {
  NamedDecl *D = Decls[I]->getUnderlyingDecl();
  D = cast<NamedDecl>(D->getCanonicalDecl());

  // Ignore an invalid declaration unless it's the only one left.
  if (D->isInvalidDecl() && !(I == 0 && N == 1)) {
    Decls[I] = Decls[--N];
    continue;
  }

  llvm::Optional<unsigned> ExistingI;

  // Redeclarations of types via typedef can occur both within a scope
  // and, through using declarations and directives, across scopes. There is
  // no ambiguity if they all refer to the same type, so unique based on the
  // canonical type.
  if (TypeDecl *TD = dyn_cast<TypeDecl>(D)) {
    QualType T = getSema().Context.getTypeDeclType(TD);
    auto UniqueResult = UniqueTypes.insert(
        std::make_pair(getSema().Context.getCanonicalType(T), I));
    if (!UniqueResult.second) {
      // The type is not unique.
      ExistingI = UniqueResult.first->second;
    }
  }

  // For non-type declarations, check for a prior lookup result naming this
  // canonical declaration.
  if (!ExistingI) {
    auto UniqueResult = Unique.insert(std::make_pair(D, I));
    if (!UniqueResult.second) {
      // We've seen this entity before.
      ExistingI = UniqueResult.first->second;
    }
  }

  if (ExistingI) {
    // This is not a unique lookup result. Pick one of the results and
    // discard the other.
    if (isPreferredLookupResult(getSema(), getLookupKind(), Decls[I],
                                Decls[*ExistingI]))
      Decls[*ExistingI] = Decls[I];
    Decls[I] = Decls[--N];
    continue;
  }

  // Otherwise, do some decl type analysis and then continue.

  if (isa<UnresolvedUsingValueDecl>(D)) {
    HasUnresolved = true;
  } else if (isa<TagDecl>(D)) {
    if (HasTag)
      Ambiguous = true;
    UniqueTagIndex = I;
    HasTag = true;
  } else if (isa<FunctionTemplateDecl>(D)) {
    HasFunction = true;
    HasFunctionTemplate = true;
  } else if (isa<FunctionDecl>(D)) {
    HasFunction = true;
  } else {
    if (HasNonFunction) {
      // If we're about to create an ambiguity between two declarations that
      // are equivalent, but one is an internal linkage declaration from one
      // module and the other is an internal linkage declaration from another
      // module, just skip it.
      if (getSema().isEquivalentInternalLinkageDeclaration(HasNonFunction,
                                                           D)) {
        EquivalentNonFunctions.push_back(D);
        Decls[I] = Decls[--N];
        continue;
      }

      Ambiguous = true;
    }
    HasNonFunction = D;
  }
  I++;
}

// C++ [basic.scope.hiding]p2:
//   A class name or enumeration name can be hidden by the name of
//   an object, function, or enumerator declared in the same
//   scope. If a class or enumeration name and an object, function,
//   or enumerator are declared in the same scope (in any order)
//   with the same name, the class or enumeration name is hidden
//   wherever the object, function, or enumerator name is visible.
// But it's still an error if there are distinct tag types found,
// even if they're not visible. (ref?)
if (N > 1 && HideTags && HasTag && !Ambiguous &&
    (HasFunction || HasNonFunction || HasUnresolved)) {
  NamedDecl *OtherDecl = Decls[UniqueTagIndex ? 0 : N - 1];
  if (isa<TagDecl>(Decls[UniqueTagIndex]->getUnderlyingDecl()) &&
      getContextForScopeMatching(Decls[UniqueTagIndex])->Equals(
          getContextForScopeMatching(OtherDecl)) &&
      canHideTag(OtherDecl))
    Decls[UniqueTagIndex] = Decls[--N];
  else
    Ambiguous = true;
}

// FIXME: This diagnostic should really be delayed until we're done with
// the lookup result, in case the ambiguity is resolved by the caller.
if (!EquivalentNonFunctions.empty() && !Ambiguous)
  getSema().diagnoseEquivalentInternalLinkageDeclarations(
      getNameLoc(), HasNonFunction, EquivalentNonFunctions);

Decls.set_size(N);

if (HasNonFunction && (HasFunction || HasUnresolved))
  Ambiguous = true;

if (Ambiguous)
  setAmbiguous(LookupResult::AmbiguousReference);
else if (HasUnresolved)
  ResultKind = LookupResult::FoundUnresolvedValue;
else if (N > 1 || HasFunctionTemplate)
  ResultKind = LookupResult::FoundOverloaded;
else
  ResultKind = LookupResult::Found;
636}

638void LookupResult::addDeclsFromBasePaths(const CXXBasePaths &P) {
CXXBasePaths::const_paths_iterator I, E;
for (I = P.begin(), E = P.end(); I != E; ++I)
  for (DeclContext::lookup_iterator DI = I->Decls, DE = DI.end(); DI != DE;
       ++DI)
    addDecl(*DI);
644}

646void LookupResult::setAmbiguousBaseSubobjects(CXXBasePaths &P) {
Paths = new CXXBasePaths;
Paths->swap(P);
addDeclsFromBasePaths(*Paths);
resolveKind();
setAmbiguous(AmbiguousBaseSubobjects);
652}

654void LookupResult::setAmbiguousBaseSubobjectTypes(CXXBasePaths &P) {
Paths = new CXXBasePaths;
Paths->swap(P);
addDeclsFromBasePaths(*Paths);
resolveKind();
setAmbiguous(AmbiguousBaseSubobjectTypes);
660}

662void LookupResult::print(raw_ostream &Out) {
Out << Decls.size() << " result(s)";
if (isAmbiguous()) Out << ", ambiguous";
if (Paths) Out << ", base paths present";

for (iterator I = begin(), E = end(); I != E; ++I) {
  Out << "\n";
  (*I)->print(Out, 2);
}
671}

673LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LookupResult::dump() {
llvm::errs() << "lookup results for " << getLookupName().getAsString()
             << ":\n";
for (NamedDecl *D : *this)
  D->dump();
678}

680/// Diagnose a missing builtin type.
681static QualType diagOpenCLBuiltinTypeError(Sema &S, llvm::StringRef TypeClass,
                                         llvm::StringRef Name) {
S.Diag(SourceLocation(), diag::err_opencl_type_not_found)
    << TypeClass << Name;
return S.Context.VoidTy;
686}

688/// Lookup an OpenCL enum type.
689static QualType getOpenCLEnumType(Sema &S, llvm::StringRef Name) {
LookupResult Result(S, &S.Context.Idents.get(Name), SourceLocation(),
                    Sema::LookupTagName);
S.LookupName(Result, S.TUScope);
if (Result.empty())
  return diagOpenCLBuiltinTypeError(S, "enum", Name);
EnumDecl *Decl = Result.getAsSingle<EnumDecl>();
if (!Decl)
  return diagOpenCLBuiltinTypeError(S, "enum", Name);
return S.Context.getEnumType(Decl);
699}

701/// Lookup an OpenCL typedef type.
702static QualType getOpenCLTypedefType(Sema &S, llvm::StringRef Name) {
LookupResult Result(S, &S.Context.Idents.get(Name), SourceLocation(),
                    Sema::LookupOrdinaryName);
S.LookupName(Result, S.TUScope);
if (Result.empty())
  return diagOpenCLBuiltinTypeError(S, "typedef", Name);
TypedefNameDecl *Decl = Result.getAsSingle<TypedefNameDecl>();
if (!Decl)
  return diagOpenCLBuiltinTypeError(S, "typedef", Name);
return S.Context.getTypedefType(Decl);
712}

714/// Get the QualType instances of the return type and arguments for an OpenCL
715/// builtin function signature.
716/// \param S (in) The Sema instance.
717/// \param OpenCLBuiltin (in) The signature currently handled.
718/// \param GenTypeMaxCnt (out) Maximum number of types contained in a generic
719///        type used as return type or as argument.
720///        Only meaningful for generic types, otherwise equals 1.
721/// \param RetTypes (out) List of the possible return types.
722/// \param ArgTypes (out) List of the possible argument types.  For each
723///        argument, ArgTypes contains QualTypes for the Cartesian product
724///        of (vector sizes) x (types) .
725static void GetQualTypesForOpenCLBuiltin(
  Sema &S, const OpenCLBuiltinStruct &OpenCLBuiltin, unsigned &GenTypeMaxCnt,
  SmallVector<QualType, 1> &RetTypes,
  SmallVector<SmallVector<QualType, 1>, 5> &ArgTypes) {
// Get the QualType instances of the return types.
unsigned Sig = SignatureTable[OpenCLBuiltin.SigTableIndex];
OCL2Qual(S, TypeTable[Sig], RetTypes);
GenTypeMaxCnt = RetTypes.size();

// Get the QualType instances of the arguments.
// First type is the return type, skip it.
for (unsigned Index = 1; Index < OpenCLBuiltin.NumTypes; Index++) {
  SmallVector<QualType, 1> Ty;
  OCL2Qual(S, TypeTable[SignatureTable[OpenCLBuiltin.SigTableIndex + Index]],
           Ty);
  GenTypeMaxCnt = (Ty.size() > GenTypeMaxCnt) ? Ty.size() : GenTypeMaxCnt;
  ArgTypes.push_back(std::move(Ty));
}
743}

745/// Create a list of the candidate function overloads for an OpenCL builtin
746/// function.
747/// \param Context (in) The ASTContext instance.
748/// \param GenTypeMaxCnt (in) Maximum number of types contained in a generic
749///        type used as return type or as argument.
750///        Only meaningful for generic types, otherwise equals 1.
751/// \param FunctionList (out) List of FunctionTypes.
752/// \param RetTypes (in) List of the possible return types.
753/// \param ArgTypes (in) List of the possible types for the arguments.
754static void GetOpenCLBuiltinFctOverloads(
  ASTContext &Context, unsigned GenTypeMaxCnt,
  std::vector<QualType> &FunctionList, SmallVector<QualType, 1> &RetTypes,
  SmallVector<SmallVector<QualType, 1>, 5> &ArgTypes) {
FunctionProtoType::ExtProtoInfo PI(
    Context.getDefaultCallingConvention(false, false, true));
PI.Variadic = false;

// Do not attempt to create any FunctionTypes if there are no return types,
// which happens when a type belongs to a disabled extension.
if (RetTypes.size() == 0)
  return;

// Create FunctionTypes for each (gen)type.
for (unsigned IGenType = 0; IGenType < GenTypeMaxCnt; IGenType++) {
  SmallVector<QualType, 5> ArgList;

  for (unsigned A = 0; A < ArgTypes.size(); A++) {
    // Bail out if there is an argument that has no available types.
    if (ArgTypes[A].size() == 0)
      return;

    // Builtins such as "max" have an "sgentype" argument that represents
    // the corresponding scalar type of a gentype.  The number of gentypes
    // must be a multiple of the number of sgentypes.
    assert(GenTypeMaxCnt % ArgTypes[A].size() == 0 &&(static_cast<void> (0))
           "argument type count not compatible with gentype type count")(static_cast<void> (0));
    unsigned Idx = IGenType % ArgTypes[A].size();
    ArgList.push_back(ArgTypes[A][Idx]);
  }

  FunctionList.push_back(Context.getFunctionType(
      RetTypes[(RetTypes.size() != 1) ? IGenType : 0], ArgList, PI));
}
788}

790/// When trying to resolve a function name, if isOpenCLBuiltin() returns a
791/// non-null <Index, Len> pair, then the name is referencing an OpenCL
792/// builtin function.  Add all candidate signatures to the LookUpResult.
793///
794/// \param S (in) The Sema instance.
795/// \param LR (inout) The LookupResult instance.
796/// \param II (in) The identifier being resolved.
797/// \param FctIndex (in) Starting index in the BuiltinTable.
798/// \param Len (in) The signature list has Len elements.
799static void InsertOCLBuiltinDeclarationsFromTable(Sema &S, LookupResult &LR,
                                                IdentifierInfo *II,
                                                const unsigned FctIndex,
                                                const unsigned Len) {
// The builtin function declaration uses generic types (gentype).
bool HasGenType = false;

// Maximum number of types contained in a generic type used as return type or
// as argument.  Only meaningful for generic types, otherwise equals 1.
unsigned GenTypeMaxCnt;

ASTContext &Context = S.Context;

for (unsigned SignatureIndex = 0; SignatureIndex < Len; SignatureIndex++) {
  const OpenCLBuiltinStruct &OpenCLBuiltin =
      BuiltinTable[FctIndex + SignatureIndex];

  // Ignore this builtin function if it is not available in the currently
  // selected language version.
  if (!isOpenCLVersionContainedInMask(Context.getLangOpts(),
                                      OpenCLBuiltin.Versions))
    continue;

  // Ignore this builtin function if it carries an extension macro that is
  // not defined. This indicates that the extension is not supported by the
  // target, so the builtin function should not be available.
  StringRef Extensions = FunctionExtensionTable[OpenCLBuiltin.Extension];
  if (!Extensions.empty()) {
    SmallVector<StringRef, 2> ExtVec;
    Extensions.split(ExtVec, " ");
    bool AllExtensionsDefined = true;
    for (StringRef Ext : ExtVec) {
      if (!S.getPreprocessor().isMacroDefined(Ext)) {
        AllExtensionsDefined = false;
        break;
      }
    }
    if (!AllExtensionsDefined)
      continue;
  }

  SmallVector<QualType, 1> RetTypes;
  SmallVector<SmallVector<QualType, 1>, 5> ArgTypes;

  // Obtain QualType lists for the function signature.
  GetQualTypesForOpenCLBuiltin(S, OpenCLBuiltin, GenTypeMaxCnt, RetTypes,
                               ArgTypes);
  if (GenTypeMaxCnt > 1) {
    HasGenType = true;
  }

  // Create function overload for each type combination.
  std::vector<QualType> FunctionList;
  GetOpenCLBuiltinFctOverloads(Context, GenTypeMaxCnt, FunctionList, RetTypes,
                               ArgTypes);

  SourceLocation Loc = LR.getNameLoc();
  DeclContext *Parent = Context.getTranslationUnitDecl();
  FunctionDecl *NewOpenCLBuiltin;

  for (const auto &FTy : FunctionList) {
    NewOpenCLBuiltin = FunctionDecl::Create(
        Context, Parent, Loc, Loc, II, FTy, /*TInfo=*/nullptr, SC_Extern,
        S.getCurFPFeatures().isFPConstrained(), false,
        FTy->isFunctionProtoType());
    NewOpenCLBuiltin->setImplicit();

    // Create Decl objects for each parameter, adding them to the
    // FunctionDecl.
    const auto *FP = cast<FunctionProtoType>(FTy);
    SmallVector<ParmVarDecl *, 4> ParmList;
    for (unsigned IParm = 0, e = FP->getNumParams(); IParm != e; ++IParm) {
      ParmVarDecl *Parm = ParmVarDecl::Create(
          Context, NewOpenCLBuiltin, SourceLocation(), SourceLocation(),
          nullptr, FP->getParamType(IParm), nullptr, SC_None, nullptr);
      Parm->setScopeInfo(0, IParm);
      ParmList.push_back(Parm);
    }
    NewOpenCLBuiltin->setParams(ParmList);

    // Add function attributes.
    if (OpenCLBuiltin.IsPure)
      NewOpenCLBuiltin->addAttr(PureAttr::CreateImplicit(Context));
    if (OpenCLBuiltin.IsConst)
      NewOpenCLBuiltin->addAttr(ConstAttr::CreateImplicit(Context));
    if (OpenCLBuiltin.IsConv)
      NewOpenCLBuiltin->addAttr(ConvergentAttr::CreateImplicit(Context));

    if (!S.getLangOpts().OpenCLCPlusPlus)
      NewOpenCLBuiltin->addAttr(OverloadableAttr::CreateImplicit(Context));

    LR.addDecl(NewOpenCLBuiltin);
  }
}

// If we added overloads, need to resolve the lookup result.
if (Len > 1 || HasGenType)
  LR.resolveKind();
897}

899/// Lookup a builtin function, when name lookup would otherwise
900/// fail.
901bool Sema::LookupBuiltin(LookupResult &R) {
Sema::LookupNameKind NameKind = R.getLookupKind();

// If we didn't find a use of this identifier, and if the identifier
// corresponds to a compiler builtin, create the decl object for the builtin
// now, injecting it into translation unit scope, and return it.
if (NameKind == Sema::LookupOrdinaryName ||
    NameKind == Sema::LookupRedeclarationWithLinkage) {
  IdentifierInfo *II = R.getLookupName().getAsIdentifierInfo();
  if (II) {
    if (getLangOpts().CPlusPlus && NameKind == Sema::LookupOrdinaryName) {
      if (II == getASTContext().getMakeIntegerSeqName()) {
        R.addDecl(getASTContext().getMakeIntegerSeqDecl());
        return true;
      } else if (II == getASTContext().getTypePackElementName()) {
        R.addDecl(getASTContext().getTypePackElementDecl());
        return true;
      }
    }

    // Check if this is an OpenCL Builtin, and if so, insert its overloads.
    if (getLangOpts().OpenCL && getLangOpts().DeclareOpenCLBuiltins) {
      auto Index = isOpenCLBuiltin(II->getName());
      if (Index.first) {
        InsertOCLBuiltinDeclarationsFromTable(*this, R, II, Index.first - 1,
                                              Index.second);
        return true;
      }
    }

    // If this is a builtin on this (or all) targets, create the decl.
    if (unsigned BuiltinID = II->getBuiltinID()) {
      // In C++ and OpenCL (spec v1.2 s6.9.f), we don't have any predefined
      // library functions like 'malloc'. Instead, we'll just error.
      if ((getLangOpts().CPlusPlus || getLangOpts().OpenCL) &&
          Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
        return false;

      if (NamedDecl *D =
              LazilyCreateBuiltin(II, BuiltinID, TUScope,
                                  R.isForRedeclaration(), R.getNameLoc())) {
        R.addDecl(D);
        return true;
      }
    }
  }
}

return false;
950}

952/// Looks up the declaration of "struct objc_super" and
953/// saves it for later use in building builtin declaration of
954/// objc_msgSendSuper and objc_msgSendSuper_stret.
955static void LookupPredefedObjCSuperType(Sema &Sema, Scope *S) {
ASTContext &Context = Sema.Context;
LookupResult Result(Sema, &Context.Idents.get("objc_super"), SourceLocation(),
                    Sema::LookupTagName);
Sema.LookupName(Result, S);
if (Result.getResultKind() == LookupResult::Found)
  if (const TagDecl *TD = Result.getAsSingle<TagDecl>())
    Context.setObjCSuperType(Context.getTagDeclType(TD));
963}

965void Sema::LookupNecessaryTypesForBuiltin(Scope *S, unsigned ID) {
if (ID == Builtin::BIobjc_msgSendSuper)
  LookupPredefedObjCSuperType(*this, S);
968}

970/// Determine whether we can declare a special member function within
971/// the class at this point.
972static bool CanDeclareSpecialMemberFunction(const CXXRecordDecl *Class) {
// We need to have a definition for the class.
if (!Class->getDefinition() || Class->isDependentContext())
  return false;

// We can't be in the middle of defining the class.
return !Class->isBeingDefined();
979}

981void Sema::ForceDeclarationOfImplicitMembers(CXXRecordDecl *Class) {
if (!CanDeclareSpecialMemberFunction(Class))
  return;

// If the default constructor has not yet been declared, do so now.
if (Class->needsImplicitDefaultConstructor())
  DeclareImplicitDefaultConstructor(Class);

// If the copy constructor has not yet been declared, do so now.
if (Class->needsImplicitCopyConstructor())
  DeclareImplicitCopyConstructor(Class);

// If the copy assignment operator has not yet been declared, do so now.
if (Class->needsImplicitCopyAssignment())
  DeclareImplicitCopyAssignment(Class);

if (getLangOpts().CPlusPlus11) {
  // If the move constructor has not yet been declared, do so now.
  if (Class->needsImplicitMoveConstructor())
    DeclareImplicitMoveConstructor(Class);

  // If the move assignment operator has not yet been declared, do so now.
  if (Class->needsImplicitMoveAssignment())
    DeclareImplicitMoveAssignment(Class);
}

// If the destructor has not yet been declared, do so now.
if (Class->needsImplicitDestructor())
  DeclareImplicitDestructor(Class);
1010}

1012/// Determine whether this is the name of an implicitly-declared
1013/// special member function.
1014static bool isImplicitlyDeclaredMemberFunctionName(DeclarationName Name) {
switch (Name.getNameKind()) {
case DeclarationName::CXXConstructorName:
case DeclarationName::CXXDestructorName:
  return true;

case DeclarationName::CXXOperatorName:
  return Name.getCXXOverloadedOperator() == OO_Equal;

default:
  break;
}

return false;
1028}

1030/// If there are any implicit member functions with the given name
1031/// that need to be declared in the given declaration context, do so.
1032static void DeclareImplicitMemberFunctionsWithName(Sema &S,
                                                 DeclarationName Name,
                                                 SourceLocation Loc,
                                                 const DeclContext *DC) {
if (!DC)
  return;

switch (Name.getNameKind()) {
case DeclarationName::CXXConstructorName:
  if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(DC))
    if (Record->getDefinition() && CanDeclareSpecialMemberFunction(Record)) {
      CXXRecordDecl *Class = const_cast<CXXRecordDecl *>(Record);
      if (Record->needsImplicitDefaultConstructor())
        S.DeclareImplicitDefaultConstructor(Class);
      if (Record->needsImplicitCopyConstructor())
        S.DeclareImplicitCopyConstructor(Class);
      if (S.getLangOpts().CPlusPlus11 &&
          Record->needsImplicitMoveConstructor())
        S.DeclareImplicitMoveConstructor(Class);
    }
  break;

case DeclarationName::CXXDestructorName:
  if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(DC))
    if (Record->getDefinition() && Record->needsImplicitDestructor() &&
        CanDeclareSpecialMemberFunction(Record))
      S.DeclareImplicitDestructor(const_cast<CXXRecordDecl *>(Record));
  break;

case DeclarationName::CXXOperatorName:
  if (Name.getCXXOverloadedOperator() != OO_Equal)
    break;

  if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(DC)) {
    if (Record->getDefinition() && CanDeclareSpecialMemberFunction(Record)) {
      CXXRecordDecl *Class = const_cast<CXXRecordDecl *>(Record);
      if (Record->needsImplicitCopyAssignment())
        S.DeclareImplicitCopyAssignment(Class);
      if (S.getLangOpts().CPlusPlus11 &&
          Record->needsImplicitMoveAssignment())
        S.DeclareImplicitMoveAssignment(Class);
    }
  }
  break;

case DeclarationName::CXXDeductionGuideName:
  S.DeclareImplicitDeductionGuides(Name.getCXXDeductionGuideTemplate(), Loc);
  break;

default:
  break;
}
1084}

1086// Adds all qualifying matches for a name within a decl context to the
1087// given lookup result.  Returns true if any matches were found.
1088static bool LookupDirect(Sema &S, LookupResult &R, const DeclContext *DC) {
bool Found = false;

// Lazily declare C++ special member functions.
if (S.getLangOpts().CPlusPlus)
5
←
Assuming field 'CPlusPlus' is 0→
6
←
Taking false branch→
  DeclareImplicitMemberFunctionsWithName(S, R.getLookupName(), R.getNameLoc(),
                                         DC);

// Perform lookup into this declaration context.
DeclContext::lookup_result DR = DC->lookup(R.getLookupName());
for (NamedDecl *D : DR) {
  if ((D = R.getAcceptableDecl(D))) {
    R.addDecl(D);
    Found = true;
  }
}

if (!Found6.1
'Found' is false
1
'Found' is false
 && DC->isTranslationUnit() && S.LookupBuiltin(R))
7
←
Calling 'DeclContext::isTranslationUnit'→
10
←
Returning from 'DeclContext::isTranslationUnit'→
  return true;

if (R.getLookupName().getNameKind()
11
←
Assuming the condition is false→
14
←
Taking false branch→
      != DeclarationName::CXXConversionFunctionName ||
    R.getLookupName().getCXXNameType()->isDependentType() ||
12
←
Assuming the condition is false→
    !isa<CXXRecordDecl>(DC))
13
←
Assuming 'DC' is a 'CXXRecordDecl'→
  return Found;

// C++ [temp.mem]p6:
//   A specialization of a conversion function template is not found by
//   name lookup. Instead, any conversion function templates visible in the
//   context of the use are considered. [...]
const CXXRecordDecl *Record = cast<CXXRecordDecl>(DC);
15
←
'DC' is a 'CXXRecordDecl'→
if (!Record->isCompleteDefinition())
16
←
Assuming the condition is false→
17
←
Taking false branch→
  return Found;

// For conversion operators, 'operator auto' should only match
// 'operator auto'.  Since 'auto' is not a type, it shouldn't be considered
// as a candidate for template substitution.
auto *ContainedDeducedType =
    R.getLookupName().getCXXNameType()->getContainedDeducedType();
if (R.getLookupName().getNameKind() ==
18
←
Taking false branch→
        DeclarationName::CXXConversionFunctionName &&
    ContainedDeducedType && ContainedDeducedType->isUndeducedType())
  return Found;

for (CXXRecordDecl::conversion_iterator U = Record->conversion_begin(),
19
←
Loop condition is true.  Entering loop body→
       UEnd = Record->conversion_end(); U != UEnd; ++U) {
  FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(*U);
20
←
Assuming the object is a 'FunctionTemplateDecl'→
  if (!ConvTemplate20.1
'ConvTemplate' is non-null
1
'ConvTemplate' is non-null
)
21
←
Taking false branch→
    continue;

  // When we're performing lookup for the purposes of redeclaration, just
  // add the conversion function template. When we deduce template
  // arguments for specializations, we'll end up unifying the return
  // type of the new declaration with the type of the function template.
  if (R.isForRedeclaration()) {
22
←
Assuming the condition is false→
23
←
Taking false branch→
    R.addDecl(ConvTemplate);
    Found = true;
    continue;
  }

  // C++ [temp.mem]p6:
  //   [...] For each such operator, if argument deduction succeeds
  //   (14.9.2.3), the resulting specialization is used as if found by
  //   name lookup.
  //
  // When referencing a conversion function for any purpose other than
  // a redeclaration (such that we'll be building an expression with the
  // result), perform template argument deduction and place the
  // specialization into the result set. We do this to avoid forcing all
  // callers to perform special deduction for conversion functions.
  TemplateDeductionInfo Info(R.getNameLoc());
  FunctionDecl *Specialization = nullptr;

  const FunctionProtoType *ConvProto
25
←
'ConvProto' initialized to a null pointer value→
    = ConvTemplate->getTemplatedDecl()->getType()->getAs<FunctionProtoType>();
24
←
Assuming the object is not a 'FunctionProtoType'→
  assert(ConvProto && "Nonsensical conversion function template type")(static_cast<void> (0));

  // Compute the type of the function that we would expect the conversion
  // function to have, if it were to match the name given.
  // FIXME: Calling convention!
  FunctionProtoType::ExtProtoInfo EPI = ConvProto->getExtProtoInfo();
26
←
Called C++ object pointer is null
  EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CC_C);
  EPI.ExceptionSpec = EST_None;
  QualType ExpectedType
    = R.getSema().Context.getFunctionType(R.getLookupName().getCXXNameType(),
                                          None, EPI);

  // Perform template argument deduction against the type that we would
  // expect the function to have.
  if (R.getSema().DeduceTemplateArguments(ConvTemplate, nullptr, ExpectedType,
                                          Specialization, Info)
        == Sema::TDK_Success) {
    R.addDecl(Specialization);
    Found = true;
  }
}

return Found;
1186}

1188// Performs C++ unqualified lookup into the given file context.
1189static bool
1190CppNamespaceLookup(Sema &S, LookupResult &R, ASTContext &Context,
                 DeclContext *NS, UnqualUsingDirectiveSet &UDirs) {

assert(NS && NS->isFileContext() && "CppNamespaceLookup() requires namespace!")(static_cast<void> (0));

// Perform direct name lookup into the LookupCtx.
bool Found = LookupDirect(S, R, NS);

// Perform direct name lookup into the namespaces nominated by the
// using directives whose common ancestor is this namespace.
for (const UnqualUsingEntry &UUE : UDirs.getNamespacesFor(NS))
  if (LookupDirect(S, R, UUE.getNominatedNamespace()))
    Found = true;

R.resolveKind();

return Found;
1207}

1209static bool isNamespaceOrTranslationUnitScope(Scope *S) {
if (DeclContext *Ctx = S->getEntity())
  return Ctx->isFileContext();
return false;
1213}

1215/// Find the outer declaration context from this scope. This indicates the
1216/// context that we should search up to (exclusive) before considering the
1217/// parent of the specified scope.
1218static DeclContext *findOuterContext(Scope *S) {
for (Scope *OuterS = S->getParent(); OuterS; OuterS = OuterS->getParent())
  if (DeclContext *DC = OuterS->getLookupEntity())
    return DC;
return nullptr;
1223}

1225namespace {
1226/// An RAII object to specify that we want to find block scope extern
1227/// declarations.
1228struct FindLocalExternScope {
FindLocalExternScope(LookupResult &R)
    : R(R), OldFindLocalExtern(R.getIdentifierNamespace() &
                               Decl::IDNS_LocalExtern) {
  R.setFindLocalExtern(R.getIdentifierNamespace() &
                       (Decl::IDNS_Ordinary | Decl::IDNS_NonMemberOperator));
}
void restore() {
  R.setFindLocalExtern(OldFindLocalExtern);
}
~FindLocalExternScope() {
  restore();
}
LookupResult &R;
bool OldFindLocalExtern;
1243};
1244} // end anonymous namespace

1246bool Sema::CppLookupName(LookupResult &R, Scope *S) {
assert(getLangOpts().CPlusPlus && "Can perform only C++ lookup")(static_cast<void> (0));

DeclarationName Name = R.getLookupName();
Sema::LookupNameKind NameKind = R.getLookupKind();

// If this is the name of an implicitly-declared special member function,
// go through the scope stack to implicitly declare
if (isImplicitlyDeclaredMemberFunctionName(Name)) {
  for (Scope *PreS = S; PreS; PreS = PreS->getParent())
    if (DeclContext *DC = PreS->getEntity())
      DeclareImplicitMemberFunctionsWithName(*this, Name, R.getNameLoc(), DC);
}

// Implicitly declare member functions with the name we're looking for, if in
// fact we are in a scope where it matters.

Scope *Initial = S;
IdentifierResolver::iterator
  I = IdResolver.begin(Name),
  IEnd = IdResolver.end();

// First we lookup local scope.
// We don't consider using-directives, as per 7.3.4.p1 [namespace.udir]
// ...During unqualified name lookup (3.4.1), the names appear as if
// they were declared in the nearest enclosing namespace which contains
// both the using-directive and the nominated namespace.
// [Note: in this context, "contains" means "contains directly or
// indirectly".
//
// For example:
// namespace A { int i; }
// void foo() {
//   int i;
//   {
//     using namespace A;
//     ++i; // finds local 'i', A::i appears at global scope
//   }
// }
//
UnqualUsingDirectiveSet UDirs(*this);
bool VisitedUsingDirectives = false;
bool LeftStartingScope = false;

// When performing a scope lookup, we want to find local extern decls.
FindLocalExternScope FindLocals(R);

for (; S && !isNamespaceOrTranslationUnitScope(S); S = S->getParent()) {
  bool SearchNamespaceScope = true;
  // Check whether the IdResolver has anything in this scope.
  for (; I != IEnd && S->isDeclScope(*I); ++I) {
    if (NamedDecl *ND = R.getAcceptableDecl(*I)) {
      if (NameKind == LookupRedeclarationWithLinkage &&
          !(*I)->isTemplateParameter()) {
        // If it's a template parameter, we still find it, so we can diagnose
        // the invalid redeclaration.

        // Determine whether this (or a previous) declaration is
        // out-of-scope.
        if (!LeftStartingScope && !Initial->isDeclScope(*I))
          LeftStartingScope = true;

        // If we found something outside of our starting scope that
        // does not have linkage, skip it.
        if (LeftStartingScope && !((*I)->hasLinkage())) {
          R.setShadowed();
          continue;
        }
      } else {
        // We found something in this scope, we should not look at the
        // namespace scope
        SearchNamespaceScope = false;
      }
      R.addDecl(ND);
    }
  }
  if (!SearchNamespaceScope) {
    R.resolveKind();
    if (S->isClassScope())
      if (CXXRecordDecl *Record =
              dyn_cast_or_null<CXXRecordDecl>(S->getEntity()))
        R.setNamingClass(Record);
    return true;
  }

  if (NameKind == LookupLocalFriendName && !S->isClassScope()) {
    // C++11 [class.friend]p11:
    //   If a friend declaration appears in a local class and the name
    //   specified is an unqualified name, a prior declaration is
    //   looked up without considering scopes that are outside the
    //   innermost enclosing non-class scope.
    return false;
  }

  if (DeclContext *Ctx = S->getLookupEntity()) {
    DeclContext *OuterCtx = findOuterContext(S);
    for (; Ctx && !Ctx->Equals(OuterCtx); Ctx = Ctx->getLookupParent()) {
      // We do not directly look into transparent contexts, since
      // those entities will be found in the nearest enclosing
      // non-transparent context.
      if (Ctx->isTransparentContext())
        continue;

      // We do not look directly into function or method contexts,
      // since all of the local variables and parameters of the
      // function/method are present within the Scope.
      if (Ctx->isFunctionOrMethod()) {
        // If we have an Objective-C instance method, look for ivars
        // in the corresponding interface.
        if (ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(Ctx)) {
          if (Method->isInstanceMethod() && Name.getAsIdentifierInfo())
            if (ObjCInterfaceDecl *Class = Method->getClassInterface()) {
              ObjCInterfaceDecl *ClassDeclared;
              if (ObjCIvarDecl *Ivar = Class->lookupInstanceVariable(
                                               Name.getAsIdentifierInfo(),
                                                           ClassDeclared)) {
                if (NamedDecl *ND = R.getAcceptableDecl(Ivar)) {
                  R.addDecl(ND);
                  R.resolveKind();
                  return true;
                }
              }
            }
        }

        continue;
      }

      // If this is a file context, we need to perform unqualified name
      // lookup considering using directives.
      if (Ctx->isFileContext()) {
        // If we haven't handled using directives yet, do so now.
        if (!VisitedUsingDirectives) {
          // Add using directives from this context up to the top level.
          for (DeclContext *UCtx = Ctx; UCtx; UCtx = UCtx->getParent()) {
            if (UCtx->isTransparentContext())
              continue;

            UDirs.visit(UCtx, UCtx);
          }

          // Find the innermost file scope, so we can add using directives
          // from local scopes.
          Scope *InnermostFileScope = S;
          while (InnermostFileScope &&
                 !isNamespaceOrTranslationUnitScope(InnermostFileScope))
            InnermostFileScope = InnermostFileScope->getParent();
          UDirs.visitScopeChain(Initial, InnermostFileScope);

          UDirs.done();

          VisitedUsingDirectives = true;
        }

        if (CppNamespaceLookup(*this, R, Context, Ctx, UDirs)) {
          R.resolveKind();
          return true;
        }

        continue;
      }

      // Perform qualified name lookup into this context.
      // FIXME: In some cases, we know that every name that could be found by
      // this qualified name lookup will also be on the identifier chain. For
      // example, inside a class without any base classes, we never need to
      // perform qualified lookup because all of the members are on top of the
      // identifier chain.
      if (LookupQualifiedName(R, Ctx, /*InUnqualifiedLookup=*/true))
        return true;
    }
  }
}

// Stop if we ran out of scopes.
// FIXME:  This really, really shouldn't be happening.
if (!S) return false;

// If we are looking for members, no need to look into global/namespace scope.
if (NameKind == LookupMemberName)
  return false;

// Collect UsingDirectiveDecls in all scopes, and recursively all
// nominated namespaces by those using-directives.
//
// FIXME: Cache this sorted list in Scope structure, and DeclContext, so we
// don't build it for each lookup!
if (!VisitedUsingDirectives) {
  UDirs.visitScopeChain(Initial, S);
  UDirs.done();
}

// If we're not performing redeclaration lookup, do not look for local
// extern declarations outside of a function scope.
if (!R.isForRedeclaration())
  FindLocals.restore();

// Lookup namespace scope, and global scope.
// Unqualified name lookup in C++ requires looking into scopes
// that aren't strictly lexical, and therefore we walk through the
// context as well as walking through the scopes.
for (; S; S = S->getParent()) {
  // Check whether the IdResolver has anything in this scope.
  bool Found = false;
  for (; I != IEnd && S->isDeclScope(*I); ++I) {
    if (NamedDecl *ND = R.getAcceptableDecl(*I)) {
      // We found something.  Look for anything else in our scope
      // with this same name and in an acceptable identifier
      // namespace, so that we can construct an overload set if we
      // need to.
      Found = true;
      R.addDecl(ND);
    }
  }

  if (Found && S->isTemplateParamScope()) {
    R.resolveKind();
    return true;
  }

  DeclContext *Ctx = S->getLookupEntity();
  if (Ctx) {
    DeclContext *OuterCtx = findOuterContext(S);
    for (; Ctx && !Ctx->Equals(OuterCtx); Ctx = Ctx->getLookupParent()) {
      // We do not directly look into transparent contexts, since
      // those entities will be found in the nearest enclosing
      // non-transparent context.
      if (Ctx->isTransparentContext())
        continue;

      // If we have a context, and it's not a context stashed in the
      // template parameter scope for an out-of-line definition, also
      // look into that context.
      if (!(Found && S->isTemplateParamScope())) {
        assert(Ctx->isFileContext() &&(static_cast<void> (0))
            "We should have been looking only at file context here already.")(static_cast<void> (0));

        // Look into context considering using-directives.
        if (CppNamespaceLookup(*this, R, Context, Ctx, UDirs))
          Found = true;
      }

      if (Found) {
        R.resolveKind();
        return true;
      }

      if (R.isForRedeclaration() && !Ctx->isTransparentContext())
        return false;
    }
  }

  if (R.isForRedeclaration() && Ctx && !Ctx->isTransparentContext())
    return false;
}

return !R.empty();
1503}

1505void Sema::makeMergedDefinitionVisible(NamedDecl *ND) {
if (auto *M = getCurrentModule())
  Context.mergeDefinitionIntoModule(ND, M);
else
  // We're not building a module; just make the definition visible.
  ND->setVisibleDespiteOwningModule();

// If ND is a template declaration, make the template parameters
// visible too. They're not (necessarily) within a mergeable DeclContext.
if (auto *TD = dyn_cast<TemplateDecl>(ND))
  for (auto *Param : *TD->getTemplateParameters())
    makeMergedDefinitionVisible(Param);
1517}

1519/// Find the module in which the given declaration was defined.
1520static Module *getDefiningModule(Sema &S, Decl *Entity) {
if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Entity)) {
  // If this function was instantiated from a template, the defining module is
  // the module containing the pattern.
  if (FunctionDecl *Pattern = FD->getTemplateInstantiationPattern())
    Entity = Pattern;
} else if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Entity)) {
  if (CXXRecordDecl *Pattern = RD->getTemplateInstantiationPattern())
    Entity = Pattern;
} else if (EnumDecl *ED = dyn_cast<EnumDecl>(Entity)) {
  if (auto *Pattern = ED->getTemplateInstantiationPattern())
    Entity = Pattern;
} else if (VarDecl *VD = dyn_cast<VarDecl>(Entity)) {
  if (VarDecl *Pattern = VD->getTemplateInstantiationPattern())
    Entity = Pattern;
}

// Walk up to the containing context. That might also have been instantiated
// from a template.
DeclContext *Context = Entity->getLexicalDeclContext();
if (Context->isFileContext())
  return S.getOwningModule(Entity);
return getDefiningModule(S, cast<Decl>(Context));
1543}

1545llvm::DenseSet<Module*> &Sema::getLookupModules() {
unsigned N = CodeSynthesisContexts.size();
for (unsigned I = CodeSynthesisContextLookupModules.size();
     I != N; ++I) {
  Module *M = CodeSynthesisContexts[I].Entity ?
              getDefiningModule(*this, CodeSynthesisContexts[I].Entity) :
              nullptr;
  if (M && !LookupModulesCache.insert(M).second)
    M = nullptr;
  CodeSynthesisContextLookupModules.push_back(M);
}
return LookupModulesCache;
1557}

1559/// Determine whether the module M is part of the current module from the
1560/// perspective of a module-private visibility check.
1561static bool isInCurrentModule(const Module *M, const LangOptions &LangOpts) {
// If M is the global module fragment of a module that we've not yet finished
// parsing, then it must be part of the current module.
return M->getTopLevelModuleName() == LangOpts.CurrentModule ||
       (M->Kind == Module::GlobalModuleFragment && !M->Parent);
1566}

1568bool Sema::hasVisibleMergedDefinition(NamedDecl *Def) {
for (const Module *Merged : Context.getModulesWithMergedDefinition(Def))
  if (isModuleVisible(Merged))
    return true;
return false;
1573}

1575bool Sema::hasMergedDefinitionInCurrentModule(NamedDecl *Def) {
for (const Module *Merged : Context.getModulesWithMergedDefinition(Def))
  if (isInCurrentModule(Merged, getLangOpts()))
    return true;
return false;
1580}

1582template<typename ParmDecl>
1583static bool
1584hasVisibleDefaultArgument(Sema &S, const ParmDecl *D,
                        llvm::SmallVectorImpl<Module *> *Modules) {
if (!D->hasDefaultArgument())
  return false;

while (D) {
  auto &DefaultArg = D->getDefaultArgStorage();
  if (!DefaultArg.isInherited() && S.isVisible(D))
    return true;

  if (!DefaultArg.isInherited() && Modules) {
    auto *NonConstD = const_cast<ParmDecl*>(D);
    Modules->push_back(S.getOwningModule(NonConstD));
  }

  // If there was a previous default argument, maybe its parameter is visible.
  D = DefaultArg.getInheritedFrom();
}
return false;
1603}

1605bool Sema::hasVisibleDefaultArgument(const NamedDecl *D,
                                   llvm::SmallVectorImpl<Module *> *Modules) {
if (auto *P = dyn_cast<TemplateTypeParmDecl>(D))
  return ::hasVisibleDefaultArgument(*this, P, Modules);
if (auto *P = dyn_cast<NonTypeTemplateParmDecl>(D))
  return ::hasVisibleDefaultArgument(*this, P, Modules);
return ::hasVisibleDefaultArgument(*this, cast<TemplateTemplateParmDecl>(D),
                                   Modules);
1613}

1615template<typename Filter>
1616static bool hasVisibleDeclarationImpl(Sema &S, const NamedDecl *D,
                                    llvm::SmallVectorImpl<Module *> *Modules,
                                    Filter F) {
bool HasFilteredRedecls = false;

for (auto *Redecl : D->redecls()) {
  auto *R = cast<NamedDecl>(Redecl);
  if (!F(R))
    continue;

  if (S.isVisible(R))
    return true;

  HasFilteredRedecls = true;

  if (Modules)
    Modules->push_back(R->getOwningModule());
}

// Only return false if there is at least one redecl that is not filtered out.
if (HasFilteredRedecls)
  return false;

return true;
1640}

1642bool Sema::hasVisibleExplicitSpecialization(
  const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
return hasVisibleDeclarationImpl(*this, D, Modules, [](const NamedDecl *D) {
  if (auto *RD = dyn_cast<CXXRecordDecl>(D))
    return RD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization;
  if (auto *FD = dyn_cast<FunctionDecl>(D))
    return FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization;
  if (auto *VD = dyn_cast<VarDecl>(D))
    return VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization;
  llvm_unreachable("unknown explicit specialization kind")__builtin_unreachable();
});
1653}

1655bool Sema::hasVisibleMemberSpecialization(
  const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
assert(isa<CXXRecordDecl>(D->getDeclContext()) &&(static_cast<void> (0))
       "not a member specialization")(static_cast<void> (0));
return hasVisibleDeclarationImpl(*this, D, Modules, [](const NamedDecl *D) {
  // If the specialization is declared at namespace scope, then it's a member
  // specialization declaration. If it's lexically inside the class
  // definition then it was instantiated.
  //
  // FIXME: This is a hack. There should be a better way to determine this.
  // FIXME: What about MS-style explicit specializations declared within a
  //        class definition?
  return D->getLexicalDeclContext()->isFileContext();
});
1669}

1671/// Determine whether a declaration is visible to name lookup.
1672///
1673/// This routine determines whether the declaration D is visible in the current
1674/// lookup context, taking into account the current template instantiation
1675/// stack. During template instantiation, a declaration is visible if it is
1676/// visible from a module containing any entity on the template instantiation
1677/// path (by instantiating a template, you allow it to see the declarations that
1678/// your module can see, including those later on in your module).
1679bool LookupResult::isVisibleSlow(Sema &SemaRef, NamedDecl *D) {
assert(!D->isUnconditionallyVisible() &&(static_cast<void> (0))
       "should not call this: not in slow case")(static_cast<void> (0));

Module *DeclModule = SemaRef.getOwningModule(D);
assert(DeclModule && "hidden decl has no owning module")(static_cast<void> (0));

// If the owning module is visible, the decl is visible.
if (SemaRef.isModuleVisible(DeclModule, D->isModulePrivate()))
  return true;

// Determine whether a decl context is a file context for the purpose of
// visibility. This looks through some (export and linkage spec) transparent
// contexts, but not others (enums).
auto IsEffectivelyFileContext = [](const DeclContext *DC) {
  return DC->isFileContext() || isa<LinkageSpecDecl>(DC) ||
         isa<ExportDecl>(DC);
};

// If this declaration is not at namespace scope
// then it is visible if its lexical parent has a visible definition.
DeclContext *DC = D->getLexicalDeclContext();
if (DC && !IsEffectivelyFileContext(DC)) {
  // For a parameter, check whether our current template declaration's
  // lexical context is visible, not whether there's some other visible
  // definition of it, because parameters aren't "within" the definition.
  //
  // In C++ we need to check for a visible definition due to ODR merging,
  // and in C we must not because each declaration of a function gets its own
  // set of declarations for tags in prototype scope.
  bool VisibleWithinParent;
  if (D->isTemplateParameter()) {
    bool SearchDefinitions = true;
    if (const auto *DCD = dyn_cast<Decl>(DC)) {
      if (const auto *TD = DCD->getDescribedTemplate()) {
        TemplateParameterList *TPL = TD->getTemplateParameters();
        auto Index = getDepthAndIndex(D).second;
        SearchDefinitions = Index >= TPL->size() || TPL->getParam(Index) != D;
      }
    }
    if (SearchDefinitions)
      VisibleWithinParent = SemaRef.hasVisibleDefinition(cast<NamedDecl>(DC));
    else
      VisibleWithinParent = isVisible(SemaRef, cast<NamedDecl>(DC));
  } else if (isa<ParmVarDecl>(D) ||
             (isa<FunctionDecl>(DC) && !SemaRef.getLangOpts().CPlusPlus))
    VisibleWithinParent = isVisible(SemaRef, cast<NamedDecl>(DC));
  else if (D->isModulePrivate()) {
    // A module-private declaration is only visible if an enclosing lexical
    // parent was merged with another definition in the current module.
    VisibleWithinParent = false;
    do {
      if (SemaRef.hasMergedDefinitionInCurrentModule(cast<NamedDecl>(DC))) {
        VisibleWithinParent = true;
        break;
      }
      DC = DC->getLexicalParent();
    } while (!IsEffectivelyFileContext(DC));
  } else {
    VisibleWithinParent = SemaRef.hasVisibleDefinition(cast<NamedDecl>(DC));
  }

  if (VisibleWithinParent && SemaRef.CodeSynthesisContexts.empty() &&
      // FIXME: Do something better in this case.
      !SemaRef.getLangOpts().ModulesLocalVisibility) {
    // Cache the fact that this declaration is implicitly visible because
    // its parent has a visible definition.
    D->setVisibleDespiteOwningModule();
  }
  return VisibleWithinParent;
}

return false;
1752}

1754bool Sema::isModuleVisible(const Module *M, bool ModulePrivate) {
// The module might be ordinarily visible. For a module-private query, that
// means it is part of the current module. For any other query, that means it
// is in our visible module set.
if (ModulePrivate) {
  if (isInCurrentModule(M, getLangOpts()))
    return true;
} else {
  if (VisibleModules.isVisible(M))
    return true;
}

// Otherwise, it might be visible by virtue of the query being within a
// template instantiation or similar that is permitted to look inside M.

// Find the extra places where we need to look.
const auto &LookupModules = getLookupModules();
if (LookupModules.empty())
  return false;

// If our lookup set contains the module, it's visible.
if (LookupModules.count(M))
  return true;

// For a module-private query, that's everywhere we get to look.
if (ModulePrivate)
  return false;

// Check whether M is transitively exported to an import of the lookup set.
return llvm::any_of(LookupModules, [&](const Module *LookupM) {
  return LookupM->isModuleVisible(M);
});
1786}

1788bool Sema::isVisibleSlow(const NamedDecl *D) {
return LookupResult::isVisible(*this, const_cast<NamedDecl*>(D));
1790}

1792bool Sema::shouldLinkPossiblyHiddenDecl(LookupResult &R, const NamedDecl *New) {
// FIXME: If there are both visible and hidden declarations, we need to take
// into account whether redeclaration is possible. Example:
//
// Non-imported module:
//   int f(T);        // #1
// Some TU:
//   static int f(U); // #2, not a redeclaration of #1
//   int f(T);        // #3, finds both, should link with #1 if T != U, but
//                    // with #2 if T == U; neither should be ambiguous.
for (auto *D : R) {
  if (isVisible(D))
    return true;
  assert(D->isExternallyDeclarable() &&(static_cast<void> (0))
         "should not have hidden, non-externally-declarable result here")(static_cast<void> (0));
}

// This function is called once "New" is essentially complete, but before a
// previous declaration is attached. We can't query the linkage of "New" in
// general, because attaching the previous declaration can change the
// linkage of New to match the previous declaration.
//
// However, because we've just determined that there is no *visible* prior
// declaration, we can compute the linkage here. There are two possibilities:
//
//  * This is not a redeclaration; it's safe to compute the linkage now.
//
//  * This is a redeclaration of a prior declaration that is externally
//    redeclarable. In that case, the linkage of the declaration is not
//    changed by attaching the prior declaration, because both are externally
//    declarable (and thus ExternalLinkage or VisibleNoLinkage).
//
// FIXME: This is subtle and fragile.
return New->isExternallyDeclarable();
1826}

1828/// Retrieve the visible declaration corresponding to D, if any.
1829///
1830/// This routine determines whether the declaration D is visible in the current
1831/// module, with the current imports. If not, it checks whether any
1832/// redeclaration of D is visible, and if so, returns that declaration.
1833///
1834/// \returns D, or a visible previous declaration of D, whichever is more recent
1835/// and visible. If no declaration of D is visible, returns null.
1836static NamedDecl *findAcceptableDecl(Sema &SemaRef, NamedDecl *D,
                                   unsigned IDNS) {
assert(!LookupResult::isVisible(SemaRef, D) && "not in slow case")(static_cast<void> (0));

for (auto RD : D->redecls()) {
  // Don't bother with extra checks if we already know this one isn't visible.
  if (RD == D)
    continue;

  auto ND = cast<NamedDecl>(RD);
  // FIXME: This is wrong in the case where the previous declaration is not
  // visible in the same scope as D. This needs to be done much more
  // carefully.
  if (ND->isInIdentifierNamespace(IDNS) &&
      LookupResult::isVisible(SemaRef, ND))
    return ND;
}

return nullptr;
1855}

1857bool Sema::hasVisibleDeclarationSlow(const NamedDecl *D,
                                   llvm::SmallVectorImpl<Module *> *Modules) {
assert(!isVisible(D) && "not in slow case")(static_cast<void> (0));
return hasVisibleDeclarationImpl(*this, D, Modules,
                                 [](const NamedDecl *) { return true; });
1862}

1864NamedDecl *LookupResult::getAcceptableDeclSlow(NamedDecl *D) const {
if (auto *ND = dyn_cast<NamespaceDecl>(D)) {
  // Namespaces are a bit of a special case: we expect there to be a lot of
  // redeclarations of some namespaces, all declarations of a namespace are
  // essentially interchangeable, all declarations are found by name lookup
  // if any is, and namespaces are never looked up during template
  // instantiation. So we benefit from caching the check in this case, and
  // it is correct to do so.
  auto *Key = ND->getCanonicalDecl();
  if (auto *Acceptable = getSema().VisibleNamespaceCache.lookup(Key))
    return Acceptable;
  auto *Acceptable = isVisible(getSema(), Key)
                         ? Key
                         : findAcceptableDecl(getSema(), Key, IDNS);
  if (Acceptable)
    getSema().VisibleNamespaceCache.insert(std::make_pair(Key, Acceptable));
  return Acceptable;
}

return findAcceptableDecl(getSema(), D, IDNS);
1884}

1886/// Perform unqualified name lookup starting from a given
1887/// scope.
1888///
1889/// Unqualified name lookup (C++ [basic.lookup.unqual], C99 6.2.1) is
1890/// used to find names within the current scope. For example, 'x' in
1891/// @code
1892/// int x;
1893/// int f() {
1894///   return x; // unqualified name look finds 'x' in the global scope
1895/// }
1896/// @endcode
1897///
1898/// Different lookup criteria can find different names. For example, a
1899/// particular scope can have both a struct and a function of the same
1900/// name, and each can be found by certain lookup criteria. For more
1901/// information about lookup criteria, see the documentation for the
1902/// class LookupCriteria.
1903///
1904/// @param S        The scope from which unqualified name lookup will
1905/// begin. If the lookup criteria permits, name lookup may also search
1906/// in the parent scopes.
1907///
1908/// @param [in,out] R Specifies the lookup to perform (e.g., the name to
1909/// look up and the lookup kind), and is updated with the results of lookup
1910/// including zero or more declarations and possibly additional information
1911/// used to diagnose ambiguities.
1912///
1913/// @returns \c true if lookup succeeded and false otherwise.
1914bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
DeclarationName Name = R.getLookupName();
if (!Name) return false;

LookupNameKind NameKind = R.getLookupKind();

if (!getLangOpts().CPlusPlus) {
  // Unqualified name lookup in C/Objective-C is purely lexical, so
  // search in the declarations attached to the name.
  if (NameKind == Sema::LookupRedeclarationWithLinkage) {
    // Find the nearest non-transparent declaration scope.
    while (!(S->getFlags() & Scope::DeclScope) ||
           (S->getEntity() && S->getEntity()->isTransparentContext()))
      S = S->getParent();
  }

  // When performing a scope lookup, we want to find local extern decls.
  FindLocalExternScope FindLocals(R);

  // Scan up the scope chain looking for a decl that matches this
  // identifier that is in the appropriate namespace.  This search
  // should not take long, as shadowing of names is uncommon, and
  // deep shadowing is extremely uncommon.
  bool LeftStartingScope = false;

  for (IdentifierResolver::iterator I = IdResolver.begin(Name),
                                 IEnd = IdResolver.end();
       I != IEnd; ++I)
    if (NamedDecl *D = R.getAcceptableDecl(*I)) {
      if (NameKind == LookupRedeclarationWithLinkage) {
        // Determine whether this (or a previous) declaration is
        // out-of-scope.
        if (!LeftStartingScope && !S->isDeclScope(*I))
          LeftStartingScope = true;

        // If we found something outside of our starting scope that
        // does not have linkage, skip it.
        if (LeftStartingScope && !((*I)->hasLinkage())) {
          R.setShadowed();
          continue;
        }
      }
      else if (NameKind == LookupObjCImplicitSelfParam &&
               !isa<ImplicitParamDecl>(*I))
        continue;

      R.addDecl(D);

      // Check whether there are any other declarations with the same name
      // and in the same scope.
      if (I != IEnd) {
        // Find the scope in which this declaration was declared (if it
        // actually exists in a Scope).
        while (S && !S->isDeclScope(D))
          S = S->getParent();

        // If the scope containing the declaration is the translation unit,
        // then we'll need to perform our checks based on the matching
        // DeclContexts rather than matching scopes.
        if (S && isNamespaceOrTranslationUnitScope(S))
          S = nullptr;

        // Compute the DeclContext, if we need it.
        DeclContext *DC = nullptr;
        if (!S)
          DC = (*I)->getDeclContext()->getRedeclContext();

        IdentifierResolver::iterator LastI = I;
        for (++LastI; LastI != IEnd; ++LastI) {
          if (S) {
            // Match based on scope.
            if (!S->isDeclScope(*LastI))
              break;
          } else {
            // Match based on DeclContext.
            DeclContext *LastDC
              = (*LastI)->getDeclContext()->getRedeclContext();
            if (!LastDC->Equals(DC))
              break;
          }

          // If the declaration is in the right namespace and visible, add it.
          if (NamedDecl *LastD = R.getAcceptableDecl(*LastI))
            R.addDecl(LastD);
        }

        R.resolveKind();
      }

      return true;
    }
} else {
  // Perform C++ unqualified name lookup.
  if (CppLookupName(R, S))
    return true;
}

// If we didn't find a use of this identifier, and if the identifier
// corresponds to a compiler builtin, create the decl object for the builtin
// now, injecting it into translation unit scope, and return it.
if (AllowBuiltinCreation && LookupBuiltin(R))
  return true;

// If we didn't find a use of this identifier, the ExternalSource
// may be able to handle the situation.
// Note: some lookup failures are expected!
// See e.g. R.isForRedeclaration().
return (ExternalSource && ExternalSource->LookupUnqualified(R, S));
2022}

2024/// Perform qualified name lookup in the namespaces nominated by
2025/// using directives by the given context.
2026///
2027/// C++98 [namespace.qual]p2:
2028///   Given X::m (where X is a user-declared namespace), or given \::m
2029///   (where X is the global namespace), let S be the set of all
2030///   declarations of m in X and in the transitive closure of all
2031///   namespaces nominated by using-directives in X and its used
2032///   namespaces, except that using-directives are ignored in any
2033///   namespace, including X, directly containing one or more
2034///   declarations of m. No namespace is searched more than once in
2035///   the lookup of a name. If S is the empty set, the program is
2036///   ill-formed. Otherwise, if S has exactly one member, or if the
2037///   context of the reference is a using-declaration
2038///   (namespace.udecl), S is the required set of declarations of
2039///   m. Otherwise if the use of m is not one that allows a unique
2040///   declaration to be chosen from S, the program is ill-formed.
2041///
2042/// C++98 [namespace.qual]p5:
2043///   During the lookup of a qualified namespace member name, if the
2044///   lookup finds more than one declaration of the member, and if one
2045///   declaration introduces a class name or enumeration name and the
2046///   other declarations either introduce the same object, the same
2047///   enumerator or a set of functions, the non-type name hides the
2048///   class or enumeration name if and only if the declarations are
2049///   from the same namespace; otherwise (the declarations are from
2050///   different namespaces), the program is ill-formed.
2051static bool LookupQualifiedNameInUsingDirectives(Sema &S, LookupResult &R,
                                               DeclContext *StartDC) {
assert(StartDC->isFileContext() && "start context is not a file context")(static_cast<void> (0));

// We have not yet looked into these namespaces, much less added
// their "using-children" to the queue.
SmallVector<NamespaceDecl*, 8> Queue;

// We have at least added all these contexts to the queue.
llvm::SmallPtrSet<DeclContext*, 8> Visited;
Visited.insert(StartDC);

// We have already looked into the initial namespace; seed the queue
// with its using-children.
for (auto *I : StartDC->using_directives()) {
  NamespaceDecl *ND = I->getNominatedNamespace()->getOriginalNamespace();
  if (S.isVisible(I) && Visited.insert(ND).second)
    Queue.push_back(ND);
}

// The easiest way to implement the restriction in [namespace.qual]p5
// is to check whether any of the individual results found a tag
// and, if so, to declare an ambiguity if the final result is not
// a tag.
bool FoundTag = false;
bool FoundNonTag = false;

LookupResult LocalR(LookupResult::Temporary, R);

bool Found = false;
while (!Queue.empty()) {
  NamespaceDecl *ND = Queue.pop_back_val();

  // We go through some convolutions here to avoid copying results
  // between LookupResults.
  bool UseLocal = !R.empty();
  LookupResult &DirectR = UseLocal ? LocalR : R;
  bool FoundDirect = LookupDirect(S, DirectR, ND);

  if (FoundDirect) {
    // First do any local hiding.
    DirectR.resolveKind();

    // If the local result is a tag, remember that.
    if (DirectR.isSingleTagDecl())
      FoundTag = true;
    else
      FoundNonTag = true;

    // Append the local results to the total results if necessary.
    if (UseLocal) {
      R.addAllDecls(LocalR);
      LocalR.clear();
    }
  }

  // If we find names in this namespace, ignore its using directives.
  if (FoundDirect) {
    Found = true;
    continue;
  }

  for (auto I : ND->using_directives()) {
    NamespaceDecl *Nom = I->getNominatedNamespace();
    if (S.isVisible(I) && Visited.insert(Nom).second)
      Queue.push_back(Nom);
  }
}

if (Found) {
  if (FoundTag && FoundNonTag)
    R.setAmbiguousQualifiedTagHiding();
  else
    R.resolveKind();
}

return Found;
2128}

2130/// Perform qualified name lookup into a given context.
2131///
2132/// Qualified name lookup (C++ [basic.lookup.qual]) is used to find
2133/// names when the context of those names is explicit specified, e.g.,
2134/// "std::vector" or "x->member", or as part of unqualified name lookup.
2135///
2136/// Different lookup criteria can find different names. For example, a
2137/// particular scope can have both a struct and a function of the same
2138/// name, and each can be found by certain lookup criteria. For more
2139/// information about lookup criteria, see the documentation for the
2140/// class LookupCriteria.
2141///
2142/// \param R captures both the lookup criteria and any lookup results found.
2143///
2144/// \param LookupCtx The context in which qualified name lookup will
2145/// search. If the lookup criteria permits, name lookup may also search
2146/// in the parent contexts or (for C++ classes) base classes.
2147///
2148/// \param InUnqualifiedLookup true if this is qualified name lookup that
2149/// occurs as part of unqualified name lookup.
2150///
2151/// \returns true if lookup succeeded, false if it failed.
2152bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
                             bool InUnqualifiedLookup) {
assert(LookupCtx && "Sema::LookupQualifiedName requires a lookup context")(static_cast<void> (0));

if (!R.getLookupName())
3
←
Taking false branch→
  return false;

// Make sure that the declaration context is complete.
assert((!isa<TagDecl>(LookupCtx) ||(static_cast<void> (0))
        LookupCtx->isDependentContext() ||(static_cast<void> (0))
        cast<TagDecl>(LookupCtx)->isCompleteDefinition() ||(static_cast<void> (0))
        cast<TagDecl>(LookupCtx)->isBeingDefined()) &&(static_cast<void> (0))
       "Declaration context must already be complete!")(static_cast<void> (0));

struct QualifiedLookupInScope {
  bool oldVal;
  DeclContext *Context;
  // Set flag in DeclContext informing debugger that we're looking for qualified name
  QualifiedLookupInScope(DeclContext *ctx) : Context(ctx) {
    oldVal = ctx->setUseQualifiedLookup();
  }
  ~QualifiedLookupInScope() {
    Context->setUseQualifiedLookup(oldVal);
  }
} QL(LookupCtx);

if (LookupDirect(*this, R, LookupCtx)) {
4
←
Calling 'LookupDirect'→
  R.resolveKind();
  if (isa<CXXRecordDecl>(LookupCtx))
    R.setNamingClass(cast<CXXRecordDecl>(LookupCtx));
  return true;
}

// Don't descend into implied contexts for redeclarations.
// C++98 [namespace.qual]p6:
//   In a declaration for a namespace member in which the
//   declarator-id is a qualified-id, given that the qualified-id
//   for the namespace member has the form
//     nested-name-specifier unqualified-id
//   the unqualified-id shall name a member of the namespace
//   designated by the nested-name-specifier.
// See also [class.mfct]p5 and [class.static.data]p2.
if (R.isForRedeclaration())
  return false;

// If this is a namespace, look it up in the implied namespaces.
if (LookupCtx->isFileContext())
  return LookupQualifiedNameInUsingDirectives(*this, R, LookupCtx);

// If this isn't a C++ class, we aren't allowed to look into base
// classes, we're done.
CXXRecordDecl *LookupRec = dyn_cast<CXXRecordDecl>(LookupCtx);
if (!LookupRec || !LookupRec->getDefinition())
  return false;

// We're done for lookups that can never succeed for C++ classes.
if (R.getLookupKind() == LookupOperatorName ||
    R.getLookupKind() == LookupNamespaceName ||
    R.getLookupKind() == LookupObjCProtocolName ||
    R.getLookupKind() == LookupLabel)
  return false;

// If we're performing qualified name lookup into a dependent class,
// then we are actually looking into a current instantiation. If we have any
// dependent base classes, then we either have to delay lookup until
// template instantiation time (at which point all bases will be available)
// or we have to fail.
if (!InUnqualifiedLookup && LookupRec->isDependentContext() &&
    LookupRec->hasAnyDependentBases()) {
  R.setNotFoundInCurrentInstantiation();
  return false;
}

// Perform lookup into our base classes.

DeclarationName Name = R.getLookupName();
unsigned IDNS = R.getIdentifierNamespace();

// Look for this member in our base classes.
auto BaseCallback = [Name, IDNS](const CXXBaseSpecifier *Specifier,
                                 CXXBasePath &Path) -> bool {
  CXXRecordDecl *BaseRecord = Specifier->getType()->getAsCXXRecordDecl();
  // Drop leading non-matching lookup results from the declaration list so
  // we don't need to consider them again below.
  for (Path.Decls = BaseRecord->lookup(Name).begin();
       Path.Decls != Path.Decls.end(); ++Path.Decls) {
    if ((*Path.Decls)->isInIdentifierNamespace(IDNS))
      return true;
  }
  return false;
};

CXXBasePaths Paths;
Paths.setOrigin(LookupRec);
if (!LookupRec->lookupInBases(BaseCallback, Paths))
  return false;

R.setNamingClass(LookupRec);

// C++ [class.member.lookup]p2:
//   [...] If the resulting set of declarations are not all from
//   sub-objects of the same type, or the set has a nonstatic member
//   and includes members from distinct sub-objects, there is an
//   ambiguity and the program is ill-formed. Otherwise that set is
//   the result of the lookup.
QualType SubobjectType;
int SubobjectNumber = 0;
AccessSpecifier SubobjectAccess = AS_none;

// Check whether the given lookup result contains only static members.
auto HasOnlyStaticMembers = [&](DeclContext::lookup_iterator Result) {
  for (DeclContext::lookup_iterator I = Result, E = I.end(); I != E; ++I)
    if ((*I)->isInIdentifierNamespace(IDNS) && (*I)->isCXXInstanceMember())
      return false;
  return true;
};

bool TemplateNameLookup = R.isTemplateNameLookup();

// Determine whether two sets of members contain the same members, as
// required by C++ [class.member.lookup]p6.
auto HasSameDeclarations = [&](DeclContext::lookup_iterator A,
                               DeclContext::lookup_iterator B) {
  using Iterator = DeclContextLookupResult::iterator;
  using Result = const void *;

  auto Next = [&](Iterator &It, Iterator End) -> Result {
    while (It != End) {
      NamedDecl *ND = *It++;
      if (!ND->isInIdentifierNamespace(IDNS))
        continue;

      // C++ [temp.local]p3:
      //   A lookup that finds an injected-class-name (10.2) can result in
      //   an ambiguity in certain cases (for example, if it is found in
      //   more than one base class). If all of the injected-class-names
      //   that are found refer to specializations of the same class
      //   template, and if the name is used as a template-name, the
      //   reference refers to the class template itself and not a
      //   specialization thereof, and is not ambiguous.
      if (TemplateNameLookup)
        if (auto *TD = getAsTemplateNameDecl(ND))
          ND = TD;

      // C++ [class.member.lookup]p3:
      //   type declarations (including injected-class-names) are replaced by
      //   the types they designate
      if (const TypeDecl *TD = dyn_cast<TypeDecl>(ND->getUnderlyingDecl())) {
        QualType T = Context.getTypeDeclType(TD);
        return T.getCanonicalType().getAsOpaquePtr();
      }

      return ND->getUnderlyingDecl()->getCanonicalDecl();
    }
    return nullptr;
  };

  // We'll often find the declarations are in the same order. Handle this
  // case (and the special case of only one declaration) efficiently.
  Iterator AIt = A, BIt = B, AEnd, BEnd;
  while (true) {
    Result AResult = Next(AIt, AEnd);
    Result BResult = Next(BIt, BEnd);
    if (!AResult && !BResult)
      return true;
    if (!AResult || !BResult)
      return false;
    if (AResult != BResult) {
      // Found a mismatch; carefully check both lists, accounting for the
      // possibility of declarations appearing more than once.
      llvm::SmallDenseMap<Result, bool, 32> AResults;
      for (; AResult; AResult = Next(AIt, AEnd))
        AResults.insert({AResult, /*FoundInB*/false});
      unsigned Found = 0;
      for (; BResult; BResult = Next(BIt, BEnd)) {
        auto It = AResults.find(BResult);
        if (It == AResults.end())
          return false;
        if (!It->second) {
          It->second = true;
          ++Found;
        }
      }
      return AResults.size() == Found;
    }
  }
};

for (CXXBasePaths::paths_iterator Path = Paths.begin(), PathEnd = Paths.end();
     Path != PathEnd; ++Path) {
  const CXXBasePathElement &PathElement = Path->back();

  // Pick the best (i.e. most permissive i.e. numerically lowest) access
  // across all paths.
  SubobjectAccess = std::min(SubobjectAccess, Path->Access);

  // Determine whether we're looking at a distinct sub-object or not.
  if (SubobjectType.isNull()) {
    // This is the first subobject we've looked at. Record its type.
    SubobjectType = Context.getCanonicalType(PathElement.Base->getType());
    SubobjectNumber = PathElement.SubobjectNumber;
    continue;
  }

  if (SubobjectType !=
      Context.getCanonicalType(PathElement.Base->getType())) {
    // We found members of the given name in two subobjects of
    // different types. If the declaration sets aren't the same, this
    // lookup is ambiguous.
    //
    // FIXME: The language rule says that this applies irrespective of
    // whether the sets contain only static members.
    if (HasOnlyStaticMembers(Path->Decls) &&
        HasSameDeclarations(Paths.begin()->Decls, Path->Decls))
      continue;

    R.setAmbiguousBaseSubobjectTypes(Paths);
    return true;
  }

  // FIXME: This language rule no longer exists. Checking for ambiguous base
  // subobjects should be done as part of formation of a class member access
  // expression (when converting the object parameter to the member's type).
  if (SubobjectNumber != PathElement.SubobjectNumber) {
    // We have a different subobject of the same type.

    // C++ [class.member.lookup]p5:
    //   A static member, a nested type or an enumerator defined in
    //   a base class T can unambiguously be found even if an object
    //   has more than one base class subobject of type T.
    if (HasOnlyStaticMembers(Path->Decls))
      continue;

    // We have found a nonstatic member name in multiple, distinct
    // subobjects. Name lookup is ambiguous.
    R.setAmbiguousBaseSubobjects(Paths);
    return true;
  }
}

// Lookup in a base class succeeded; return these results.

for (DeclContext::lookup_iterator I = Paths.front().Decls, E = I.end();
     I != E; ++I) {
  AccessSpecifier AS = CXXRecordDecl::MergeAccess(SubobjectAccess,
                                                  (*I)->getAccess());
  if (NamedDecl *ND = R.getAcceptableDecl(*I))
    R.addDecl(ND, AS);
}
R.resolveKind();
return true;
2403}

2405/// Performs qualified name lookup or special type of lookup for
2406/// "__super::" scope specifier.
2407///
2408/// This routine is a convenience overload meant to be called from contexts
2409/// that need to perform a qualified name lookup with an optional C++ scope
2410/// specifier that might require special kind of lookup.
2411///
2412/// \param R captures both the lookup criteria and any lookup results found.
2413///
2414/// \param LookupCtx The context in which qualified name lookup will
2415/// search.
2416///
2417/// \param SS An optional C++ scope-specifier.
2418///
2419/// \returns true if lookup succeeded, false if it failed.
2420bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
                             CXXScopeSpec &SS) {
auto *NNS = SS.getScopeRep();
if (NNS && NNS->getKind() == NestedNameSpecifier::Super)
1
Assuming 'NNS' is null→
  return LookupInSuper(R, NNS->getAsRecordDecl());
else

  return LookupQualifiedName(R, LookupCtx);
2
←
Calling 'Sema::LookupQualifiedName'→
2428}

2430/// Performs name lookup for a name that was parsed in the
2431/// source code, and may contain a C++ scope specifier.
2432///
2433/// This routine is a convenience routine meant to be called from
2434/// contexts that receive a name and an optional C++ scope specifier
2435/// (e.g., "N::M::x"). It will then perform either qualified or
2436/// unqualified name lookup (with LookupQualifiedName or LookupName,
2437/// respectively) on the given name and return those results. It will
2438/// perform a special type of lookup for "__super::" scope specifier.
2439///
2440/// @param S        The scope from which unqualified name lookup will
2441/// begin.
2442///
2443/// @param SS       An optional C++ scope-specifier, e.g., "::N::M".
2444///
2445/// @param EnteringContext Indicates whether we are going to enter the
2446/// context of the scope-specifier SS (if present).
2447///
2448/// @returns True if any decls were found (but possibly ambiguous)
2449bool Sema::LookupParsedName(LookupResult &R, Scope *S, CXXScopeSpec *SS,
                          bool AllowBuiltinCreation, bool EnteringContext) {
if (SS && SS->isInvalid()) {
  // When the scope specifier is invalid, don't even look for
  // anything.
  return false;
}

if (SS && SS->isSet()) {
  NestedNameSpecifier *NNS = SS->getScopeRep();
  if (NNS->getKind() == NestedNameSpecifier::Super)
    return LookupInSuper(R, NNS->getAsRecordDecl());

  if (DeclContext *DC = computeDeclContext(*SS, EnteringContext)) {
    // We have resolved the scope specifier to a particular declaration
    // contex, and will perform name lookup in that context.
    if (!DC->isDependentContext() && RequireCompleteDeclContext(*SS, DC))
      return false;

    R.setContextRange(SS->getRange());
    return LookupQualifiedName(R, DC);
  }

  // We could not resolve the scope specified to a specific declaration
  // context, which means that SS refers to an unknown specialization.
  // Name lookup can't find anything in this case.
  R.setNotFoundInCurrentInstantiation();
  R.setContextRange(SS->getRange());
  return false;
}

// Perform unqualified name lookup starting in the given scope.
return LookupName(R, S, AllowBuiltinCreation);
2482}

2484/// Perform qualified name lookup into all base classes of the given
2485/// class.
2486///
2487/// \param R captures both the lookup criteria and any lookup results found.
2488///
2489/// \param Class The context in which qualified name lookup will
2490/// search. Name lookup will search in all base classes merging the results.
2491///
2492/// @returns True if any decls were found (but possibly ambiguous)
2493bool Sema::LookupInSuper(LookupResult &R, CXXRecordDecl *Class) {
// The access-control rules we use here are essentially the rules for
// doing a lookup in Class that just magically skipped the direct
// members of Class itself.  That is, the naming class is Class, and the
// access includes the access of the base.
for (const auto &BaseSpec : Class->bases()) {
  CXXRecordDecl *RD = cast<CXXRecordDecl>(
      BaseSpec.getType()->castAs<RecordType>()->getDecl());
  LookupResult Result(*this, R.getLookupNameInfo(), R.getLookupKind());
  Result.setBaseObjectType(Context.getRecordType(Class));
  LookupQualifiedName(Result, RD);

  // Copy the lookup results into the target, merging the base's access into
  // the path access.
  for (auto I = Result.begin(), E = Result.end(); I != E; ++I) {
    R.addDecl(I.getDecl(),
              CXXRecordDecl::MergeAccess(BaseSpec.getAccessSpecifier(),
                                         I.getAccess()));
  }

  Result.suppressDiagnostics();
}

R.resolveKind();
R.setNamingClass(Class);

return !R.empty();
2520}

2522/// Produce a diagnostic describing the ambiguity that resulted
2523/// from name lookup.
2524///
2525/// \param Result The result of the ambiguous lookup to be diagnosed.
2526void Sema::DiagnoseAmbiguousLookup(LookupResult &Result) {
assert(Result.isAmbiguous() && "Lookup result must be ambiguous")(static_cast<void> (0));

DeclarationName Name = Result.getLookupName();
SourceLocation NameLoc = Result.getNameLoc();
SourceRange LookupRange = Result.getContextRange();

switch (Result.getAmbiguityKind()) {
case LookupResult::AmbiguousBaseSubobjects: {
  CXXBasePaths *Paths = Result.getBasePaths();
  QualType SubobjectType = Paths->front().back().Base->getType();
  Diag(NameLoc, diag::err_ambiguous_member_multiple_subobjects)
    << Name << SubobjectType << getAmbiguousPathsDisplayString(*Paths)
    << LookupRange;

  DeclContext::lookup_iterator Found = Paths->front().Decls;
  while (isa<CXXMethodDecl>(*Found) &&
         cast<CXXMethodDecl>(*Found)->isStatic())
    ++Found;

  Diag((*Found)->getLocation(), diag::note_ambiguous_member_found);
  break;
}

case LookupResult::AmbiguousBaseSubobjectTypes: {
  Diag(NameLoc, diag::err_ambiguous_member_multiple_subobject_types)
    << Name << LookupRange;

  CXXBasePaths *Paths = Result.getBasePaths();
  std::set<const NamedDecl *> DeclsPrinted;
  for (CXXBasePaths::paths_iterator Path = Paths->begin(),
                                    PathEnd = Paths->end();
       Path != PathEnd; ++Path) {
    const NamedDecl *D = *Path->Decls;
    if (!D->isInIdentifierNamespace(Result.getIdentifierNamespace()))
      continue;
    if (DeclsPrinted.insert(D).second) {
      if (const auto *TD = dyn_cast<TypedefNameDecl>(D->getUnderlyingDecl()))
        Diag(D->getLocation(), diag::note_ambiguous_member_type_found)
            << TD->getUnderlyingType();
      else if (const auto *TD = dyn_cast<TypeDecl>(D->getUnderlyingDecl()))
        Diag(D->getLocation(), diag::note_ambiguous_member_type_found)
            << Context.getTypeDeclType(TD);
      else
        Diag(D->getLocation(), diag::note_ambiguous_member_found);
    }
  }
  break;
}

case LookupResult::AmbiguousTagHiding: {
  Diag(NameLoc, diag::err_ambiguous_tag_hiding) << Name << LookupRange;

  llvm::SmallPtrSet<NamedDecl*, 8> TagDecls;

  for (auto *D : Result)
    if (TagDecl *TD = dyn_cast<TagDecl>(D)) {
      TagDecls.insert(TD);
      Diag(TD->getLocation(), diag::note_hidden_tag);
    }

  for (auto *D : Result)
    if (!isa<TagDecl>(D))
      Diag(D->getLocation(), diag::note_hiding_object);

  // For recovery purposes, go ahead and implement the hiding.
  LookupResult::Filter F = Result.makeFilter();
  while (F.hasNext()) {
    if (TagDecls.count(F.next()))
      F.erase();
  }
  F.done();
  break;
}

case LookupResult::AmbiguousReference: {
  Diag(NameLoc, diag::err_ambiguous_reference) << Name << LookupRange;

  for (auto *D : Result)
    Diag(D->getLocation(), diag::note_ambiguous_candidate) << D;
  break;
}
}
2609}

2611namespace {
struct AssociatedLookup {
  AssociatedLookup(Sema &S, SourceLocation InstantiationLoc,
                   Sema::AssociatedNamespaceSet &Namespaces,
                   Sema::AssociatedClassSet &Classes)
    : S(S), Namespaces(Namespaces), Classes(Classes),
      InstantiationLoc(InstantiationLoc) {
  }

  bool addClassTransitive(CXXRecordDecl *RD) {
    Classes.insert(RD);
    return ClassesTransitive.insert(RD);
  }

  Sema &S;
  Sema::AssociatedNamespaceSet &Namespaces;
  Sema::AssociatedClassSet &Classes;
  SourceLocation InstantiationLoc;

private:
  Sema::AssociatedClassSet ClassesTransitive;
};
2633} // end anonymous namespace

2635static void
2636addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType T);

2638// Given the declaration context \param Ctx of a class, class template or
2639// enumeration, add the associated namespaces to \param Namespaces as described
2640// in [basic.lookup.argdep]p2.
2641static void CollectEnclosingNamespace(Sema::AssociatedNamespaceSet &Namespaces,
                                    DeclContext *Ctx) {
// The exact wording has been changed in C++14 as a result of
// CWG 1691 (see also CWG 1690 and CWG 1692). We apply it unconditionally
// to all language versions since it is possible to return a local type
// from a lambda in C++11.
//
// C++14 [basic.lookup.argdep]p2:
//   If T is a class type [...]. Its associated namespaces are the innermost
//   enclosing namespaces of its associated classes. [...]
//
//   If T is an enumeration type, its associated namespace is the innermost
//   enclosing namespace of its declaration. [...]

// We additionally skip inline namespaces. The innermost non-inline namespace
// contains all names of all its nested inline namespaces anyway, so we can
// replace the entire inline namespace tree with its root.
while (!Ctx->isFileContext() || Ctx->isInlineNamespace())
  Ctx = Ctx->getParent();

Namespaces.insert(Ctx->getPrimaryContext());
2662}

2664// Add the associated classes and namespaces for argument-dependent
2665// lookup that involves a template argument (C++ [basic.lookup.argdep]p2).
2666static void
2667addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
                                const TemplateArgument &Arg) {
// C++ [basic.lookup.argdep]p2, last bullet:
//   -- [...] ;
switch (Arg.getKind()) {
  case TemplateArgument::Null:
    break;

  case TemplateArgument::Type:
    // [...] the namespaces and classes associated with the types of the
    // template arguments provided for template type parameters (excluding
    // template template parameters)
    addAssociatedClassesAndNamespaces(Result, Arg.getAsType());
    break;

  case TemplateArgument::Template:
  case TemplateArgument::TemplateExpansion: {
    // [...] the namespaces in which any template template arguments are
    // defined; and the classes in which any member templates used as
    // template template arguments are defined.
    TemplateName Template = Arg.getAsTemplateOrTemplatePattern();
    if (ClassTemplateDecl *ClassTemplate
               = dyn_cast<ClassTemplateDecl>(Template.getAsTemplateDecl())) {
      DeclContext *Ctx = ClassTemplate->getDeclContext();
      if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
        Result.Classes.insert(EnclosingClass);
      // Add the associated namespace for this class.
      CollectEnclosingNamespace(Result.Namespaces, Ctx);
    }
    break;
  }

  case TemplateArgument::Declaration:
  case TemplateArgument::Integral:
  case TemplateArgument::Expression:
  case TemplateArgument::NullPtr:
    // [Note: non-type template arguments do not contribute to the set of
    //  associated namespaces. ]
    break;

  case TemplateArgument::Pack:
    for (const auto &P : Arg.pack_elements())
      addAssociatedClassesAndNamespaces(Result, P);
    break;
}
2712}

2714// Add the associated classes and namespaces for argument-dependent lookup
2715// with an argument of class type (C++ [basic.lookup.argdep]p2).
2716static void
2717addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
                                CXXRecordDecl *Class) {

// Just silently ignore anything whose name is __va_list_tag.
if (Class->getDeclName() == Result.S.VAListTagName)
  return;

// C++ [basic.lookup.argdep]p2:
//   [...]
//     -- If T is a class type (including unions), its associated
//        classes are: the class itself; the class of which it is a
//        member, if any; and its direct and indirect base classes.
//        Its associated namespaces are the innermost enclosing
//        namespaces of its associated classes.

// Add the class of which it is a member, if any.
DeclContext *Ctx = Class->getDeclContext();
if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
  Result.Classes.insert(EnclosingClass);

// Add the associated namespace for this class.
CollectEnclosingNamespace(Result.Namespaces, Ctx);

// -- If T is a template-id, its associated namespaces and classes are
//    the namespace in which the template is defined; for member
//    templates, the member template's class; the namespaces and classes
//    associated with the types of the template arguments provided for
//    template type parameters (excluding template template parameters); the
//    namespaces in which any template template arguments are defined; and
//    the classes in which any member templates used as template template
//    arguments are defined. [Note: non-type template arguments do not
//    contribute to the set of associated namespaces. ]
if (ClassTemplateSpecializationDecl *Spec
      = dyn_cast<ClassTemplateSpecializationDecl>(Class)) {
  DeclContext *Ctx = Spec->getSpecializedTemplate()->getDeclContext();
  if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
    Result.Classes.insert(EnclosingClass);
  // Add the associated namespace for this class.
  CollectEnclosingNamespace(Result.Namespaces, Ctx);

  const TemplateArgumentList &TemplateArgs = Spec->getTemplateArgs();
  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
    addAssociatedClassesAndNamespaces(Result, TemplateArgs[I]);
}

// Add the class itself. If we've already transitively visited this class,
// we don't need to visit base classes.
if (!Result.addClassTransitive(Class))
  return;

// Only recurse into base classes for complete types.
if (!Result.S.isCompleteType(Result.InstantiationLoc,
                             Result.S.Context.getRecordType(Class)))
  return;

// Add direct and indirect base classes along with their associated
// namespaces.
SmallVector<CXXRecordDecl *, 32> Bases;
Bases.push_back(Class);
while (!Bases.empty()) {
  // Pop this class off the stack.
  Class = Bases.pop_back_val();

  // Visit the base classes.
  for (const auto &Base : Class->bases()) {
    const RecordType *BaseType = Base.getType()->getAs<RecordType>();
    // In dependent contexts, we do ADL twice, and the first time around,
    // the base type might be a dependent TemplateSpecializationType, or a
    // TemplateTypeParmType. If that happens, simply ignore it.
    // FIXME: If we want to support export, we probably need to add the
    // namespace of the template in a TemplateSpecializationType, or even
    // the classes and namespaces of known non-dependent arguments.
    if (!BaseType)
      continue;
    CXXRecordDecl *BaseDecl = cast<CXXRecordDecl>(BaseType->getDecl());
    if (Result.addClassTransitive(BaseDecl)) {
      // Find the associated namespace for this base class.
      DeclContext *BaseCtx = BaseDecl->getDeclContext();
      CollectEnclosingNamespace(Result.Namespaces, BaseCtx);

      // Make sure we visit the bases of this base class.
      if (BaseDecl->bases_begin() != BaseDecl->bases_end())
        Bases.push_back(BaseDecl);
    }
  }
}
2803}

2805// Add the associated classes and namespaces for
2806// argument-dependent lookup with an argument of type T
2807// (C++ [basic.lookup.koenig]p2).
2808static void
2809addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
// C++ [basic.lookup.koenig]p2:
//
//   For each argument type T in the function call, there is a set
//   of zero or more associated namespaces and a set of zero or more
//   associated classes to be considered. The sets of namespaces and
//   classes is determined entirely by the types of the function
//   arguments (and the namespace of any template template
//   argument). Typedef names and using-declarations used to specify
//   the types do not contribute to this set. The sets of namespaces
//   and classes are determined in the following way:

SmallVector<const Type *, 16> Queue;
const Type *T = Ty->getCanonicalTypeInternal().getTypePtr();

while (true) {
  switch (T->getTypeClass()) {

2827#define TYPE(Class, Base)
2828#define DEPENDENT_TYPE(Class, Base) case Type::Class:
2829#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
2830#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
2831#define ABSTRACT_TYPE(Class, Base)
2832#include "clang/AST/TypeNodes.inc"
    // T is canonical.  We can also ignore dependent types because
    // we don't need to do ADL at the definition point, but if we
    // wanted to implement template export (or if we find some other
    // use for associated classes and namespaces...) this would be
    // wrong.
    break;

  //    -- If T is a pointer to U or an array of U, its associated
  //       namespaces and classes are those associated with U.
  case Type::Pointer:
    T = cast<PointerType>(T)->getPointeeType().getTypePtr();
    continue;
  case Type::ConstantArray:
  case Type::IncompleteArray:
  case Type::VariableArray:
    T = cast<ArrayType>(T)->getElementType().getTypePtr();
    continue;

  //     -- If T is a fundamental type, its associated sets of
  //        namespaces and classes are both empty.
  case Type::Builtin:
    break;

  //     -- If T is a class type (including unions), its associated
  //        classes are: the class itself; the class of which it is
  //        a member, if any; and its direct and indirect base classes.
  //        Its associated namespaces are the innermost enclosing
  //        namespaces of its associated classes.
  case Type::Record: {
    CXXRecordDecl *Class =
        cast<CXXRecordDecl>(cast<RecordType>(T)->getDecl());
    addAssociatedClassesAndNamespaces(Result, Class);
    break;
  }

  //     -- If T is an enumeration type, its associated namespace
  //        is the innermost enclosing namespace of its declaration.
  //        If it is a class member, its associated class is the
  //        member’s class; else it has no associated class.
  case Type::Enum: {
    EnumDecl *Enum = cast<EnumType>(T)->getDecl();

    DeclContext *Ctx = Enum->getDeclContext();
    if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
      Result.Classes.insert(EnclosingClass);

    // Add the associated namespace for this enumeration.
    CollectEnclosingNamespace(Result.Namespaces, Ctx);

    break;
  }

  //     -- If T is a function type, its associated namespaces and
  //        classes are those associated with the function parameter
  //        types and those associated with the return type.
  case Type::FunctionProto: {
    const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
    for (const auto &Arg : Proto->param_types())
      Queue.push_back(Arg.getTypePtr());
    // fallthrough
    LLVM_FALLTHROUGH[[gnu::fallthrough]];
  }
  case Type::FunctionNoProto: {
    const FunctionType *FnType = cast<FunctionType>(T);
    T = FnType->getReturnType().getTypePtr();
    continue;
  }

  //     -- If T is a pointer to a member function of a class X, its
  //        associated namespaces and classes are those associated
  //        with the function parameter types and return type,
  //        together with those associated with X.
  //
  //     -- If T is a pointer to a data member of class X, its
  //        associated namespaces and classes are those associated
  //        with the member type together with those associated with
  //        X.
  case Type::MemberPointer: {
    const MemberPointerType *MemberPtr = cast<MemberPointerType>(T);

    // Queue up the class type into which this points.
    Queue.push_back(MemberPtr->getClass());

    // And directly continue with the pointee type.
    T = MemberPtr->getPointeeType().getTypePtr();
    continue;
  }

  // As an extension, treat this like a normal pointer.
  case Type::BlockPointer:
    T = cast<BlockPointerType>(T)->getPointeeType().getTypePtr();
    continue;

  // References aren't covered by the standard, but that's such an
  // obvious defect that we cover them anyway.
  case Type::LValueReference:
  case Type::RValueReference:
    T = cast<ReferenceType>(T)->getPointeeType().getTypePtr();
    continue;

  // These are fundamental types.
  case Type::Vector:
  case Type::ExtVector:
  case Type::ConstantMatrix:
  case Type::Complex:
  case Type::ExtInt:
    break;

  // Non-deduced auto types only get here for error cases.
  case Type::Auto:
  case Type::DeducedTemplateSpecialization:
    break;

  // If T is an Objective-C object or interface type, or a pointer to an
  // object or interface type, the associated namespace is the global
  // namespace.
  case Type::ObjCObject:
  case Type::ObjCInterface:
  case Type::ObjCObjectPointer:
    Result.Namespaces.insert(Result.S.Context.getTranslationUnitDecl());
    break;

  // Atomic types are just wrappers; use the associations of the
  // contained type.
  case Type::Atomic:
    T = cast<AtomicType>(T)->getValueType().getTypePtr();
    continue;
  case Type::Pipe:
    T = cast<PipeType>(T)->getElementType().getTypePtr();
    continue;
  }

  if (Queue.empty())
    break;
  T = Queue.pop_back_val();
}
2969}

2971/// Find the associated classes and namespaces for
2972/// argument-dependent lookup for a call with the given set of
2973/// arguments.
2974///
2975/// This routine computes the sets of associated classes and associated
2976/// namespaces searched by argument-dependent lookup
2977/// (C++ [basic.lookup.argdep]) for a given set of arguments.
2978void Sema::FindAssociatedClassesAndNamespaces(
  SourceLocation InstantiationLoc, ArrayRef<Expr *> Args,
  AssociatedNamespaceSet &AssociatedNamespaces,
  AssociatedClassSet &AssociatedClasses) {
AssociatedNamespaces.clear();
AssociatedClasses.clear();

AssociatedLookup Result(*this, InstantiationLoc,
                        AssociatedNamespaces, AssociatedClasses);

// C++ [basic.lookup.koenig]p2:
//   For each argument type T in the function call, there is a set
//   of zero or more associated namespaces and a set of zero or more
//   associated classes to be considered. The sets of namespaces and
//   classes is determined entirely by the types of the function
//   arguments (and the namespace of any template template
//   argument).
for (unsigned ArgIdx = 0; ArgIdx != Args.size(); ++ArgIdx) {
  Expr *Arg = Args[ArgIdx];

  if (Arg->getType() != Context.OverloadTy) {
    addAssociatedClassesAndNamespaces(Result, Arg->getType());
    continue;
  }

  // [...] In addition, if the argument is the name or address of a
  // set of overloaded functions and/or function templates, its
  // associated classes and namespaces are the union of those
  // associated with each of the members of the set: the namespace
  // in which the function or function template is defined and the
  // classes and namespaces associated with its (non-dependent)
  // parameter types and return type.
  OverloadExpr *OE = OverloadExpr::find(Arg).Expression;

  for (const NamedDecl *D : OE->decls()) {
    // Look through any using declarations to find the underlying function.
    const FunctionDecl *FDecl = D->getUnderlyingDecl()->getAsFunction();

    // Add the classes and namespaces associated with the parameter
    // types and return type of this function.
    addAssociatedClassesAndNamespaces(Result, FDecl->getType());
  }
}
3021}

3023NamedDecl *Sema::LookupSingleName(Scope *S, DeclarationName Name,
                                SourceLocation Loc,
                                LookupNameKind NameKind,
                                RedeclarationKind Redecl) {
LookupResult R(*this, Name, Loc, NameKind, Redecl);
LookupName(R, S);
return R.getAsSingle<NamedDecl>();
3030}

3032/// Find the protocol with the given name, if any.
3033ObjCProtocolDecl *Sema::LookupProtocol(IdentifierInfo *II,
                                     SourceLocation IdLoc,
                                     RedeclarationKind Redecl) {
Decl *D = LookupSingleName(TUScope, II, IdLoc,
                           LookupObjCProtocolName, Redecl);
return cast_or_null<ObjCProtocolDecl>(D);
3039}

3041void Sema::LookupOverloadedOperatorName(OverloadedOperatorKind Op, Scope *S,
                                      UnresolvedSetImpl &Functions) {
// C++ [over.match.oper]p3:
//     -- The set of non-member candidates is the result of the
//        unqualified lookup of operator@ in the context of the
//        expression according to the usual rules for name lookup in
//        unqualified function calls (3.4.2) except that all member
//        functions are ignored.
DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);
LookupResult Operators(*this, OpName, SourceLocation(), LookupOperatorName);
LookupName(Operators, S);

assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous")(static_cast<void> (0));
Functions.append(Operators.begin(), Operators.end());
3055}

3057Sema::SpecialMemberOverloadResult Sema::LookupSpecialMember(CXXRecordDecl *RD,
                                                         CXXSpecialMember SM,
                                                         bool ConstArg,
                                                         bool VolatileArg,
                                                         bool RValueThis,
                                                         bool ConstThis,
                                                         bool VolatileThis) {
assert(CanDeclareSpecialMemberFunction(RD) &&(static_cast<void> (0))
       "doing special member lookup into record that isn't fully complete")(static_cast<void> (0));
RD = RD->getDefinition();
if (RValueThis || ConstThis || VolatileThis)
  assert((SM == CXXCopyAssignment || SM == CXXMoveAssignment) &&(static_cast<void> (0))
         "constructors and destructors always have unqualified lvalue this")(static_cast<void> (0));
if (ConstArg || VolatileArg)
  assert((SM != CXXDefaultConstructor && SM != CXXDestructor) &&(static_cast<void> (0))
         "parameter-less special members can't have qualified arguments")(static_cast<void> (0));

// FIXME: Get the caller to pass in a location for the lookup.
SourceLocation LookupLoc = RD->getLocation();

llvm::FoldingSetNodeID ID;
ID.AddPointer(RD);
ID.AddInteger(SM);
ID.AddInteger(ConstArg);
ID.AddInteger(VolatileArg);
ID.AddInteger(RValueThis);
ID.AddInteger(ConstThis);
ID.AddInteger(VolatileThis);

void *InsertPoint;
SpecialMemberOverloadResultEntry *Result =
  SpecialMemberCache.FindNodeOrInsertPos(ID, InsertPoint);

// This was already cached
if (Result)
  return *Result;

Result = BumpAlloc.Allocate<SpecialMemberOverloadResultEntry>();
Result = new (Result) SpecialMemberOverloadResultEntry(ID);
SpecialMemberCache.InsertNode(Result, InsertPoint);

if (SM == CXXDestructor) {
  if (RD->needsImplicitDestructor()) {
    runWithSufficientStackSpace(RD->getLocation(), [&] {
      DeclareImplicitDestructor(RD);
    });
  }
  CXXDestructorDecl *DD = RD->getDestructor();
  Result->setMethod(DD);
  Result->setKind(DD && !DD->isDeleted()
                      ? SpecialMemberOverloadResult::Success
                      : SpecialMemberOverloadResult::NoMemberOrDeleted);
  return *Result;
}

// Prepare for overload resolution. Here we construct a synthetic argument
// if necessary and make sure that implicit functions are declared.
CanQualType CanTy = Context.getCanonicalType(Context.getTagDeclType(RD));
DeclarationName Name;
Expr *Arg = nullptr;
unsigned NumArgs;

QualType ArgType = CanTy;
ExprValueKind VK = VK_LValue;

if (SM == CXXDefaultConstructor) {
  Name = Context.DeclarationNames.getCXXConstructorName(CanTy);
  NumArgs = 0;
  if (RD->needsImplicitDefaultConstructor()) {
    runWithSufficientStackSpace(RD->getLocation(), [&] {
      DeclareImplicitDefaultConstructor(RD);
    });
  }
} else {
  if (SM == CXXCopyConstructor || SM == CXXMoveConstructor) {
    Name = Context.DeclarationNames.getCXXConstructorName(CanTy);
    if (RD->needsImplicitCopyConstructor()) {
      runWithSufficientStackSpace(RD->getLocation(), [&] {
        DeclareImplicitCopyConstructor(RD);
      });
    }
    if (getLangOpts().CPlusPlus11 && RD->needsImplicitMoveConstructor()) {
      runWithSufficientStackSpace(RD->getLocation(), [&] {
        DeclareImplicitMoveConstructor(RD);
      });
    }
  } else {
    Name = Context.DeclarationNames.getCXXOperatorName(OO_Equal);
    if (RD->needsImplicitCopyAssignment()) {
      runWithSufficientStackSpace(RD->getLocation(), [&] {
        DeclareImplicitCopyAssignment(RD);
      });
    }
    if (getLangOpts().CPlusPlus11 && RD->needsImplicitMoveAssignment()) {
      runWithSufficientStackSpace(RD->getLocation(), [&] {
        DeclareImplicitMoveAssignment(RD);
      });
    }
  }

  if (ConstArg)
    ArgType.addConst();
  if (VolatileArg)
    ArgType.addVolatile();

  // This isn't /really/ specified by the standard, but it's implied
  // we should be working from a PRValue in the case of move to ensure
  // that we prefer to bind to rvalue references, and an LValue in the
  // case of copy to ensure we don't bind to rvalue references.
  // Possibly an XValue is actually correct in the case of move, but
  // there is no semantic difference for class types in this restricted
  // case.
  if (SM == CXXCopyConstructor || SM == CXXCopyAssignment)
    VK = VK_LValue;
  else
    VK = VK_PRValue;
}

OpaqueValueExpr FakeArg(LookupLoc, ArgType, VK);

if (SM != CXXDefaultConstructor) {
  NumArgs = 1;
  Arg = &FakeArg;
}

// Create the object argument
QualType ThisTy = CanTy;
if (ConstThis)
  ThisTy.addConst();
if (VolatileThis)
  ThisTy.addVolatile();
Expr::Classification Classification =
    OpaqueValueExpr(LookupLoc, ThisTy, RValueThis ? VK_PRValue : VK_LValue)
        .Classify(Context);

// Now we perform lookup on the name we computed earlier and do overload
// resolution. Lookup is only performed directly into the class since there
// will always be a (possibly implicit) declaration to shadow any others.
OverloadCandidateSet OCS(LookupLoc, OverloadCandidateSet::CSK_Normal);
DeclContext::lookup_result R = RD->lookup(Name);

if (R.empty()) {
  // We might have no default constructor because we have a lambda's closure
  // type, rather than because there's some other declared constructor.
  // Every class has a copy/move constructor, copy/move assignment, and
  // destructor.
  assert(SM == CXXDefaultConstructor &&(static_cast<void> (0))
         "lookup for a constructor or assignment operator was empty")(static_cast<void> (0));
  Result->setMethod(nullptr);
  Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
  return *Result;
}

// Copy the candidates as our processing of them may load new declarations
// from an external source and invalidate lookup_result.
SmallVector<NamedDecl *, 8> Candidates(R.begin(), R.end());

for (NamedDecl *CandDecl : Candidates) {
  if (CandDecl->isInvalidDecl())
    continue;

  DeclAccessPair Cand = DeclAccessPair::make(CandDecl, AS_public);
  auto CtorInfo = getConstructorInfo(Cand);
  if (CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(Cand->getUnderlyingDecl())) {
    if (SM == CXXCopyAssignment || SM == CXXMoveAssignment)
      AddMethodCandidate(M, Cand, RD, ThisTy, Classification,
                         llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
    else if (CtorInfo)
      AddOverloadCandidate(CtorInfo.Constructor, CtorInfo.FoundDecl,
                           llvm::makeArrayRef(&Arg, NumArgs), OCS,
                           /*SuppressUserConversions*/ true);
    else
      AddOverloadCandidate(M, Cand, llvm::makeArrayRef(&Arg, NumArgs), OCS,
                           /*SuppressUserConversions*/ true);
  } else if (FunctionTemplateDecl *Tmpl =
               dyn_cast<FunctionTemplateDecl>(Cand->getUnderlyingDecl())) {
    if (SM == CXXCopyAssignment || SM == CXXMoveAssignment)
      AddMethodTemplateCandidate(
          Tmpl, Cand, RD, nullptr, ThisTy, Classification,
          llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
    else if (CtorInfo)
      AddTemplateOverloadCandidate(
          CtorInfo.ConstructorTmpl, CtorInfo.FoundDecl, nullptr,
          llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
    else
      AddTemplateOverloadCandidate(
          Tmpl, Cand, nullptr, llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
  } else {
    assert(isa<UsingDecl>(Cand.getDecl()) &&(static_cast<void> (0))
           "illegal Kind of operator = Decl")(static_cast<void> (0));
  }
}

OverloadCandidateSet::iterator Best;
switch (OCS.BestViableFunction(*this, LookupLoc, Best)) {
  case OR_Success:
    Result->setMethod(cast<CXXMethodDecl>(Best->Function));
    Result->setKind(SpecialMemberOverloadResult::Success);
    break;

  case OR_Deleted:
    Result->setMethod(cast<CXXMethodDecl>(Best->Function));
    Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
    break;

  case OR_Ambiguous:
    Result->setMethod(nullptr);
    Result->setKind(SpecialMemberOverloadResult::Ambiguous);
    break;

  case OR_No_Viable_Function:
    Result->setMethod(nullptr);
    Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
    break;
}

return *Result;
3274}

3276/// Look up the default constructor for the given class.
3277CXXConstructorDecl *Sema::LookupDefaultConstructor(CXXRecordDecl *Class) {
SpecialMemberOverloadResult Result =
  LookupSpecialMember(Class, CXXDefaultConstructor, false, false, false,
                      false, false);

return cast_or_null<CXXConstructorDecl>(Result.getMethod());
3283}

3285/// Look up the copying constructor for the given class.
3286CXXConstructorDecl *Sema::LookupCopyingConstructor(CXXRecordDecl *Class,
                                                 unsigned Quals) {
assert(!(Quals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&(static_cast<void> (0))
       "non-const, non-volatile qualifiers for copy ctor arg")(static_cast<void> (0));
SpecialMemberOverloadResult Result =
  LookupSpecialMember(Class, CXXCopyConstructor, Quals & Qualifiers::Const,
                      Quals & Qualifiers::Volatile, false, false, false);

return cast_or_null<CXXConstructorDecl>(Result.getMethod());
3295}

3297/// Look up the moving constructor for the given class.
3298CXXConstructorDecl *Sema::LookupMovingConstructor(CXXRecordDecl *Class,
                                                unsigned Quals) {
SpecialMemberOverloadResult Result =
  LookupSpecialMember(Class, CXXMoveConstructor, Quals & Qualifiers::Const,
                      Quals & Qualifiers::Volatile, false, false, false);

return cast_or_null<CXXConstructorDecl>(Result.getMethod());
3305}

3307/// Look up the constructors for the given class.
3308DeclContext::lookup_result Sema::LookupConstructors(CXXRecordDecl *Class) {
// If the implicit constructors have not yet been declared, do so now.
if (CanDeclareSpecialMemberFunction(Class)) {
  runWithSufficientStackSpace(Class->getLocation(), [&] {
    if (Class->needsImplicitDefaultConstructor())
      DeclareImplicitDefaultConstructor(Class);
    if (Class->needsImplicitCopyConstructor())
      DeclareImplicitCopyConstructor(Class);
    if (getLangOpts().CPlusPlus11 && Class->needsImplicitMoveConstructor())
      DeclareImplicitMoveConstructor(Class);
  });
}

CanQualType T = Context.getCanonicalType(Context.getTypeDeclType(Class));
DeclarationName Name = Context.DeclarationNames.getCXXConstructorName(T);
return Class->lookup(Name);
3324}

3326/// Look up the copying assignment operator for the given class.
3327CXXMethodDecl *Sema::LookupCopyingAssignment(CXXRecordDecl *Class,
                                           unsigned Quals, bool RValueThis,
                                           unsigned ThisQuals) {
assert(!(Quals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&(static_cast<void> (0))
       "non-const, non-volatile qualifiers for copy assignment arg")(static_cast<void> (0));
assert(!(ThisQuals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&(static_cast<void> (0))
       "non-const, non-volatile qualifiers for copy assignment this")(static_cast<void> (0));
SpecialMemberOverloadResult Result =
  LookupSpecialMember(Class, CXXCopyAssignment, Quals & Qualifiers::Const,
                      Quals & Qualifiers::Volatile, RValueThis,
                      ThisQuals & Qualifiers::Const,
                      ThisQuals & Qualifiers::Volatile);

return Result.getMethod();
3341}

3343/// Look up the moving assignment operator for the given class.
3344CXXMethodDecl *Sema::LookupMovingAssignment(CXXRecordDecl *Class,
                                          unsigned Quals,
                                          bool RValueThis,
                                          unsigned ThisQuals) {
assert(!(ThisQuals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&(static_cast<void> (0))
       "non-const, non-volatile qualifiers for copy assignment this")(static_cast<void> (0));
SpecialMemberOverloadResult Result =
  LookupSpecialMember(Class, CXXMoveAssignment, Quals & Qualifiers::Const,
                      Quals & Qualifiers::Volatile, RValueThis,
                      ThisQuals & Qualifiers::Const,
                      ThisQuals & Qualifiers::Volatile);

return Result.getMethod();
3357}

3359/// Look for the destructor of the given class.
3360///
3361/// During semantic analysis, this routine should be used in lieu of
3362/// CXXRecordDecl::getDestructor().
3363///
3364/// \returns The destructor for this class.
3365CXXDestructorDecl *Sema::LookupDestructor(CXXRecordDecl *Class) {
return cast<CXXDestructorDecl>(LookupSpecialMember(Class, CXXDestructor,
                                                   false, false, false,
                                                   false, false).getMethod());
3369}

3371/// LookupLiteralOperator - Determine which literal operator should be used for
3372/// a user-defined literal, per C++11 [lex.ext].
3373///
3374/// Normal overload resolution is not used to select which literal operator to
3375/// call for a user-defined literal. Look up the provided literal operator name,
3376/// and filter the results to the appropriate set for the given argument types.
3377Sema::LiteralOperatorLookupResult
3378Sema::LookupLiteralOperator(Scope *S, LookupResult &R,
                          ArrayRef<QualType> ArgTys, bool AllowRaw,
                          bool AllowTemplate, bool AllowStringTemplatePack,
                          bool DiagnoseMissing, StringLiteral *StringLit) {
LookupName(R, S);
assert(R.getResultKind() != LookupResult::Ambiguous &&(static_cast<void> (0))
       "literal operator lookup can't be ambiguous")(static_cast<void> (0));

// Filter the lookup results appropriately.
LookupResult::Filter F = R.makeFilter();

bool AllowCooked = true;
bool FoundRaw = false;
bool FoundTemplate = false;
bool FoundStringTemplatePack = false;
bool FoundCooked = false;

while (F.hasNext()) {
  Decl *D = F.next();
  if (UsingShadowDecl *USD = dyn_cast<UsingShadowDecl>(D))
    D = USD->getTargetDecl();

  // If the declaration we found is invalid, skip it.
  if (D->isInvalidDecl()) {
    F.erase();
    continue;
  }

  bool IsRaw = false;
  bool IsTemplate = false;
  bool IsStringTemplatePack = false;
  bool IsCooked = false;

  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
    if (FD->getNumParams() == 1 &&
        FD->getParamDecl(0)->getType()->getAs<PointerType>())
      IsRaw = true;
    else if (FD->getNumParams() == ArgTys.size()) {
      IsCooked = true;
      for (unsigned ArgIdx = 0; ArgIdx != ArgTys.size(); ++ArgIdx) {
        QualType ParamTy = FD->getParamDecl(ArgIdx)->getType();
        if (!Context.hasSameUnqualifiedType(ArgTys[ArgIdx], ParamTy)) {
          IsCooked = false;
          break;
        }
      }
    }
  }
  if (FunctionTemplateDecl *FD = dyn_cast<FunctionTemplateDecl>(D)) {
    TemplateParameterList *Params = FD->getTemplateParameters();
    if (Params->size() == 1) {
      IsTemplate = true;
      if (!Params->getParam(0)->isTemplateParameterPack() && !StringLit) {
        // Implied but not stated: user-defined integer and floating literals
        // only ever use numeric literal operator templates, not templates
        // taking a parameter of class type.
        F.erase();
        continue;
      }

      // A string literal template is only considered if the string literal
      // is a well-formed template argument for the template parameter.
      if (StringLit) {
        SFINAETrap Trap(*this);
        SmallVector<TemplateArgument, 1> Checked;
        TemplateArgumentLoc Arg(TemplateArgument(StringLit), StringLit);
        if (CheckTemplateArgument(Params->getParam(0), Arg, FD,
                                  R.getNameLoc(), R.getNameLoc(), 0,
                                  Checked) ||
            Trap.hasErrorOccurred())
          IsTemplate = false;
      }
    } else {
      IsStringTemplatePack = true;
    }
  }

  if (AllowTemplate && StringLit && IsTemplate) {
    FoundTemplate = true;
    AllowRaw = false;
    AllowCooked = false;
    AllowStringTemplatePack = false;
    if (FoundRaw || FoundCooked || FoundStringTemplatePack) {
      F.restart();
      FoundRaw = FoundCooked = FoundStringTemplatePack = false;
    }
  } else if (AllowCooked && IsCooked) {
    FoundCooked = true;
    AllowRaw = false;
    AllowTemplate = StringLit;
    AllowStringTemplatePack = false;
    if (FoundRaw || FoundTemplate || FoundStringTemplatePack) {
      // Go through again and remove the raw and template decls we've
      // already found.
      F.restart();
      FoundRaw = FoundTemplate = FoundStringTemplatePack = false;
    }
  } else if (AllowRaw && IsRaw) {
    FoundRaw = true;
  } else if (AllowTemplate && IsTemplate) {
    FoundTemplate = true;
  } else if (AllowStringTemplatePack && IsStringTemplatePack) {
    FoundStringTemplatePack = true;
  } else {
    F.erase();
  }
}

F.done();

// Per C++20 [lex.ext]p5, we prefer the template form over the non-template
// form for string literal operator templates.
if (StringLit && FoundTemplate)
  return LOLR_Template;

// C++11 [lex.ext]p3, p4: If S contains a literal operator with a matching
// parameter type, that is used in preference to a raw literal operator
// or literal operator template.
if (FoundCooked)
  return LOLR_Cooked;

// C++11 [lex.ext]p3, p4: S shall contain a raw literal operator or a literal
// operator template, but not both.
if (FoundRaw && FoundTemplate) {
  Diag(R.getNameLoc(), diag::err_ovl_ambiguous_call) << R.getLookupName();
  for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
    NoteOverloadCandidate(*I, (*I)->getUnderlyingDecl()->getAsFunction());
  return LOLR_Error;
}

if (FoundRaw)
  return LOLR_Raw;

if (FoundTemplate)
  return LOLR_Template;

if (FoundStringTemplatePack)
  return LOLR_StringTemplatePack;

// Didn't find anything we could use.
if (DiagnoseMissing) {
  Diag(R.getNameLoc(), diag::err_ovl_no_viable_literal_operator)
      << R.getLookupName() << (int)ArgTys.size() << ArgTys[0]
      << (ArgTys.size() == 2 ? ArgTys[1] : QualType()) << AllowRaw
      << (AllowTemplate || AllowStringTemplatePack);
  return LOLR_Error;
}

return LOLR_ErrorNoDiagnostic;
3527}

3529void ADLResult::insert(NamedDecl *New) {
NamedDecl *&Old = Decls[cast<NamedDecl>(New->getCanonicalDecl())];

// If we haven't yet seen a decl for this key, or the last decl
// was exactly this one, we're done.
if (Old == nullptr || Old == New) {
  Old = New;
  return;
}

// Otherwise, decide which is a more recent redeclaration.
FunctionDecl *OldFD = Old->getAsFunction();
FunctionDecl *NewFD = New->getAsFunction();

FunctionDecl *Cursor = NewFD;
while (true) {
  Cursor = Cursor->getPreviousDecl();

  // If we got to the end without finding OldFD, OldFD is the newer
  // declaration;  leave things as they are.
  if (!Cursor) return;

  // If we do find OldFD, then NewFD is newer.
  if (Cursor == OldFD) break;

  // Otherwise, keep looking.
}

Old = New;
3558}

3560void Sema::ArgumentDependentLookup(DeclarationName Name, SourceLocation Loc,
                                 ArrayRef<Expr *> Args, ADLResult &Result) {
// Find all of the associated namespaces and classes based on the
// arguments we have.
AssociatedNamespaceSet AssociatedNamespaces;
AssociatedClassSet AssociatedClasses;
FindAssociatedClassesAndNamespaces(Loc, Args,
                                   AssociatedNamespaces,
                                   AssociatedClasses);

// C++ [basic.lookup.argdep]p3:
//   Let X be the lookup set produced by unqualified lookup (3.4.1)
//   and let Y be the lookup set produced by argument dependent
//   lookup (defined as follows). If X contains [...] then Y is
//   empty. Otherwise Y is the set of declarations found in the
//   namespaces associated with the argument types as described
//   below. The set of declarations found by the lookup of the name
//   is the union of X and Y.
//
// Here, we compute Y and add its members to the overloaded
// candidate set.
for (auto *NS : AssociatedNamespaces) {
  //   When considering an associated namespace, the lookup is the
  //   same as the lookup performed when the associated namespace is
  //   used as a qualifier (3.4.3.2) except that:
  //
  //     -- Any using-directives in the associated namespace are
  //        ignored.
  //
  //     -- Any namespace-scope friend functions declared in
  //        associated classes are visible within their respective
  //        namespaces even if they are not visible during an ordinary
  //        lookup (11.4).
  DeclContext::lookup_result R = NS->lookup(Name);
  for (auto *D : R) {
    auto *Underlying = D;
    if (auto *USD = dyn_cast<UsingShadowDecl>(D))
      Underlying = USD->getTargetDecl();

    if (!isa<FunctionDecl>(Underlying) &&
        !isa<FunctionTemplateDecl>(Underlying))
      continue;

    // The declaration is visible to argument-dependent lookup if either
    // it's ordinarily visible or declared as a friend in an associated
    // class.
    bool Visible = false;
    for (D = D->getMostRecentDecl(); D;
         D = cast_or_null<NamedDecl>(D->getPreviousDecl())) {
      if (D->getIdentifierNamespace() & Decl::IDNS_Ordinary) {
        if (isVisible(D)) {
          Visible = true;
          break;
        }
      } else if (D->getFriendObjectKind()) {
        auto *RD = cast<CXXRecordDecl>(D->getLexicalDeclContext());
        if (AssociatedClasses.count(RD) && isVisible(D)) {
          Visible = true;
          break;
        }
      }
    }

    // FIXME: Preserve D as the FoundDecl.
    if (Visible)
      Result.insert(Underlying);
  }
}
3628}

3630//----------------------------------------------------------------------------
3631// Search for all visible declarations.
3632//----------------------------------------------------------------------------
3633VisibleDeclConsumer::~VisibleDeclConsumer() { }

3635bool VisibleDeclConsumer::includeHiddenDecls() const { return false; }

3637namespace {

3639class ShadowContextRAII;

3641class VisibleDeclsRecord {
3642public:
/// An entry in the shadow map, which is optimized to store a
/// single declaration (the common case) but can also store a list
/// of declarations.
typedef llvm::TinyPtrVector<NamedDecl*> ShadowMapEntry;

3648private:
/// A mapping from declaration names to the declarations that have
/// this name within a particular scope.
typedef llvm::DenseMap<DeclarationName, ShadowMapEntry> ShadowMap;

/// A list of shadow maps, which is used to model name hiding.
std::list<ShadowMap> ShadowMaps;

/// The declaration contexts we have already visited.
llvm::SmallPtrSet<DeclContext *, 8> VisitedContexts;

friend class ShadowContextRAII;

3661public:
/// Determine whether we have already visited this context
/// (and, if not, note that we are going to visit that context now).
bool visitedContext(DeclContext *Ctx) {
  return !VisitedContexts.insert(Ctx).second;
}

bool alreadyVisitedContext(DeclContext *Ctx) {
  return VisitedContexts.count(Ctx);
}

/// Determine whether the given declaration is hidden in the
/// current scope.
///
/// \returns the declaration that hides the given declaration, or
/// NULL if no such declaration exists.
NamedDecl *checkHidden(NamedDecl *ND);

/// Add a declaration to the current shadow map.
void add(NamedDecl *ND) {
  ShadowMaps.back()[ND->getDeclName()].push_back(ND);
}
3683};

3685/// RAII object that records when we've entered a shadow context.
3686class ShadowContextRAII {
VisibleDeclsRecord &Visible;

typedef VisibleDeclsRecord::ShadowMap ShadowMap;

3691public:
ShadowContextRAII(VisibleDeclsRecord &Visible) : Visible(Visible) {
  Visible.ShadowMaps.emplace_back();
}

~ShadowContextRAII() {
  Visible.ShadowMaps.pop_back();
}
3699};

3701} // end anonymous namespace

3703NamedDecl *VisibleDeclsRecord::checkHidden(NamedDecl *ND) {
unsigned IDNS = ND->getIdentifierNamespace();
std::list<ShadowMap>::reverse_iterator SM = ShadowMaps.rbegin();
for (std::list<ShadowMap>::reverse_iterator SMEnd = ShadowMaps.rend();
     SM != SMEnd; ++SM) {
  ShadowMap::iterator Pos = SM->find(ND->getDeclName());
  if (Pos == SM->end())
    continue;

  for (auto *D : Pos->second) {
    // A tag declaration does not hide a non-tag declaration.
    if (D->hasTagIdentifierNamespace() &&
        (IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary |
                 Decl::IDNS_ObjCProtocol)))
      continue;

    // Protocols are in distinct namespaces from everything else.
    if (((D->getIdentifierNamespace() & Decl::IDNS_ObjCProtocol)
         || (IDNS & Decl::IDNS_ObjCProtocol)) &&
        D->getIdentifierNamespace() != IDNS)
      continue;

    // Functions and function templates in the same scope overload
    // rather than hide.  FIXME: Look for hiding based on function
    // signatures!
    if (D->getUnderlyingDecl()->isFunctionOrFunctionTemplate() &&
        ND->getUnderlyingDecl()->isFunctionOrFunctionTemplate() &&
        SM == ShadowMaps.rbegin())
      continue;

    // A shadow declaration that's created by a resolved using declaration
    // is not hidden by the same using declaration.
    if (isa<UsingShadowDecl>(ND) && isa<UsingDecl>(D) &&
        cast<UsingShadowDecl>(ND)->getIntroducer() == D)
      continue;

    // We've found a declaration that hides this one.
    return D;
  }
}

return nullptr;
3745}

3747namespace {
3748class LookupVisibleHelper {
3749public:
LookupVisibleHelper(VisibleDeclConsumer &Consumer, bool IncludeDependentBases,
                    bool LoadExternal)
    : Consumer(Consumer), IncludeDependentBases(IncludeDependentBases),
      LoadExternal(LoadExternal) {}

void lookupVisibleDecls(Sema &SemaRef, Scope *S, Sema::LookupNameKind Kind,
                        bool IncludeGlobalScope) {
  // Determine the set of using directives available during
  // unqualified name lookup.
  Scope *Initial = S;
  UnqualUsingDirectiveSet UDirs(SemaRef);
  if (SemaRef.getLangOpts().CPlusPlus) {
    // Find the first namespace or translation-unit scope.
    while (S && !isNamespaceOrTranslationUnitScope(S))
      S = S->getParent();

    UDirs.visitScopeChain(Initial, S);
  }
  UDirs.done();

  // Look for visible declarations.
  LookupResult Result(SemaRef, DeclarationName(), SourceLocation(), Kind);
  Result.setAllowHidden(Consumer.includeHiddenDecls());
  if (!IncludeGlobalScope)
    Visited.visitedContext(SemaRef.getASTContext().getTranslationUnitDecl());
  ShadowContextRAII Shadow(Visited);
  lookupInScope(Initial, Result, UDirs);
}

void lookupVisibleDecls(Sema &SemaRef, DeclContext *Ctx,
                        Sema::LookupNameKind Kind, bool IncludeGlobalScope) {
  LookupResult Result(SemaRef, DeclarationName(), SourceLocation(), Kind);
  Result.setAllowHidden(Consumer.includeHiddenDecls());
  if (!IncludeGlobalScope)
    Visited.visitedContext(SemaRef.getASTContext().getTranslationUnitDecl());

  ShadowContextRAII Shadow(Visited);
  lookupInDeclContext(Ctx, Result, /*QualifiedNameLookup=*/true,
                      /*InBaseClass=*/false);
}

3791private:
void lookupInDeclContext(DeclContext *Ctx, LookupResult &Result,
                         bool QualifiedNameLookup, bool InBaseClass) {
  if (!Ctx)
    return;

  // Make sure we don't visit the same context twice.
  if (Visited.visitedContext(Ctx->getPrimaryContext()))
    return;

  Consumer.EnteredContext(Ctx);

  // Outside C++, lookup results for the TU live on identifiers.
  if (isa<TranslationUnitDecl>(Ctx) &&
      !Result.getSema().getLangOpts().CPlusPlus) {
    auto &S = Result.getSema();
    auto &Idents = S.Context.Idents;

    // Ensure all external identifiers are in the identifier table.
    if (LoadExternal)
      if (IdentifierInfoLookup *External =
              Idents.getExternalIdentifierLookup()) {
        std::unique_ptr<IdentifierIterator> Iter(External->getIdentifiers());
        for (StringRef Name = Iter->Next(); !Name.empty();
             Name = Iter->Next())
          Idents.get(Name);
      }

    // Walk all lookup results in the TU for each identifier.
    for (const auto &Ident : Idents) {
      for (auto I = S.IdResolver.begin(Ident.getValue()),
                E = S.IdResolver.end();
           I != E; ++I) {
        if (S.IdResolver.isDeclInScope(*I, Ctx)) {
          if (NamedDecl *ND = Result.getAcceptableDecl(*I)) {
            Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
            Visited.add(ND);
          }
        }
      }
    }

    return;
  }

  if (CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(Ctx))
    Result.getSema().ForceDeclarationOfImplicitMembers(Class);

  llvm::SmallVector<NamedDecl *, 4> DeclsToVisit;
  // We sometimes skip loading namespace-level results (they tend to be huge).
  bool Load = LoadExternal ||
              !(isa<TranslationUnitDecl>(Ctx) || isa<NamespaceDecl>(Ctx));
  // Enumerate all of the results in this context.
  for (DeclContextLookupResult R :
       Load ? Ctx->lookups()
            : Ctx->noload_lookups(/*PreserveInternalState=*/false)) {
    for (auto *D : R) {
      if (auto *ND = Result.getAcceptableDecl(D)) {
        // Rather than visit immediatelly, we put ND into a vector and visit
        // all decls, in order, outside of this loop. The reason is that
        // Consumer.FoundDecl() may invalidate the iterators used in the two
        // loops above.
        DeclsToVisit.push_back(ND);
      }
    }
  }

  for (auto *ND : DeclsToVisit) {
    Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
    Visited.add(ND);
  }
  DeclsToVisit.clear();

  // Traverse using directives for qualified name lookup.
  if (QualifiedNameLookup) {
    ShadowContextRAII Shadow(Visited);
    for (auto I : Ctx->using_directives()) {
      if (!Result.getSema().isVisible(I))
        continue;
      lookupInDeclContext(I->getNominatedNamespace(), Result,
                          QualifiedNameLookup, InBaseClass);
    }
  }

  // Traverse the contexts of inherited C++ classes.
  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx)) {
    if (!Record->hasDefinition())
      return;

    for (const auto &B : Record->bases()) {
      QualType BaseType = B.getType();

      RecordDecl *RD;
      if (BaseType->isDependentType()) {
        if (!IncludeDependentBases) {
          // Don't look into dependent bases, because name lookup can't look
          // there anyway.
          continue;
        }
        const auto *TST = BaseType->getAs<TemplateSpecializationType>();
        if (!TST)
          continue;
        TemplateName TN = TST->getTemplateName();
        const auto *TD =
            dyn_cast_or_null<ClassTemplateDecl>(TN.getAsTemplateDecl());
        if (!TD)
          continue;
        RD = TD->getTemplatedDecl();
      } else {
        const auto *Record = BaseType->getAs<RecordType>();
        if (!Record)
          continue;
        RD = Record->getDecl();
      }

      // FIXME: It would be nice to be able to determine whether referencing
      // a particular member would be ambiguous. For example, given
      //
      //   struct A { int member; };
      //   struct B { int member; };
      //   struct C : A, B { };
      //
      //   void f(C *c) { c->### }
      //
      // accessing 'member' would result in an ambiguity. However, we
      // could be smart enough to qualify the member with the base
      // class, e.g.,
      //
      //   c->B::member
      //
      // or
      //
      //   c->A::member

      // Find results in this base class (and its bases).
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(RD, Result, QualifiedNameLookup,
                          /*InBaseClass=*/true);
    }
  }

  // Traverse the contexts of Objective-C classes.
  if (ObjCInterfaceDecl *IFace = dyn_cast<ObjCInterfaceDecl>(Ctx)) {
    // Traverse categories.
    for (auto *Cat : IFace->visible_categories()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(Cat, Result, QualifiedNameLookup,
                          /*InBaseClass=*/false);
    }

    // Traverse protocols.
    for (auto *I : IFace->all_referenced_protocols()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(I, Result, QualifiedNameLookup,
                          /*InBaseClass=*/false);
    }

    // Traverse the superclass.
    if (IFace->getSuperClass()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(IFace->getSuperClass(), Result, QualifiedNameLookup,
                          /*InBaseClass=*/true);
    }

    // If there is an implementation, traverse it. We do this to find
    // synthesized ivars.
    if (IFace->getImplementation()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(IFace->getImplementation(), Result,
                          QualifiedNameLookup, InBaseClass);
    }
  } else if (ObjCProtocolDecl *Protocol = dyn_cast<ObjCProtocolDecl>(Ctx)) {
    for (auto *I : Protocol->protocols()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(I, Result, QualifiedNameLookup,
                          /*InBaseClass=*/false);
    }
  } else if (ObjCCategoryDecl *Category = dyn_cast<ObjCCategoryDecl>(Ctx)) {
    for (auto *I : Category->protocols()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(I, Result, QualifiedNameLookup,
                          /*InBaseClass=*/false);
    }

    // If there is an implementation, traverse it.
    if (Category->getImplementation()) {
      ShadowContextRAII Shadow(Visited);
      lookupInDeclContext(Category->getImplementation(), Result,
                          QualifiedNameLookup, /*InBaseClass=*/true);
    }
  }
}

void lookupInScope(Scope *S, LookupResult &Result,
                   UnqualUsingDirectiveSet &UDirs) {
  // No clients run in this mode and it's not supported. Please add tests and
  // remove the assertion if you start relying on it.
  assert(!IncludeDependentBases && "Unsupported flag for lookupInScope")(static_cast<void> (0));

  if (!S)
    return;

  if (!S->getEntity() ||
      (!S->getParent() && !Visited.alreadyVisitedContext(S->getEntity())) ||
      (S->getEntity())->isFunctionOrMethod()) {
    FindLocalExternScope FindLocals(Result);
    // Walk through the declarations in this Scope. The consumer might add new
    // decls to the scope as part of deserialization, so make a copy first.
    SmallVector<Decl *, 8> ScopeDecls(S->decls().begin(), S->decls().end());
    for (Decl *D : ScopeDecls) {
      if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
        if ((ND = Result.getAcceptableDecl(ND))) {
          Consumer.FoundDecl(ND, Visited.checkHidden(ND), nullptr, false);
          Visited.add(ND);
        }
    }
  }

  DeclContext *Entity = S->getLookupEntity();
  if (Entity) {
    // Look into this scope's declaration context, along with any of its
    // parent lookup contexts (e.g., enclosing classes), up to the point
    // where we hit the context stored in the next outer scope.
    DeclContext *OuterCtx = findOuterContext(S);

    for (DeclContext *Ctx = Entity; Ctx && !Ctx->Equals(OuterCtx);
         Ctx = Ctx->getLookupParent()) {
      if (ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(Ctx)) {
        if (Method->isInstanceMethod()) {
          // For instance methods, look for ivars in the method's interface.
          LookupResult IvarResult(Result.getSema(), Result.getLookupName(),
                                  Result.getNameLoc(),
                                  Sema::LookupMemberName);
          if (ObjCInterfaceDecl *IFace = Method->getClassInterface()) {
            lookupInDeclContext(IFace, IvarResult,
                                /*QualifiedNameLookup=*/false,
                                /*InBaseClass=*/false);
          }
        }

        // We've already performed all of the name lookup that we need
        // to for Objective-C methods; the next context will be the
        // outer scope.
        break;
      }

      if (Ctx->isFunctionOrMethod())
        continue;

      lookupInDeclContext(Ctx, Result, /*QualifiedNameLookup=*/false,
                          /*InBaseClass=*/false);
    }
  } else if (!S->getParent()) {
    // Look into the translation unit scope. We walk through the translation
    // unit's declaration context, because the Scope itself won't have all of
    // the declarations if we loaded a precompiled header.
    // FIXME: We would like the translation unit's Scope object to point to
    // the translation unit, so we don't need this special "if" branch.
    // However, doing so would force the normal C++ name-lookup code to look
    // into the translation unit decl when the IdentifierInfo chains would
    // suffice. Once we fix that problem (which is part of a more general
    // "don't look in DeclContexts unless we have to" optimization), we can
    // eliminate this.
    Entity = Result.getSema().Context.getTranslationUnitDecl();
    lookupInDeclContext(Entity, Result, /*QualifiedNameLookup=*/false,
                        /*InBaseClass=*/false);
  }

  if (Entity) {
    // Lookup visible declarations in any namespaces found by using
    // directives.
    for (const UnqualUsingEntry &UUE : UDirs.getNamespacesFor(Entity))
      lookupInDeclContext(
          const_cast<DeclContext *>(UUE.getNominatedNamespace()), Result,
          /*QualifiedNameLookup=*/false,
          /*InBaseClass=*/false);
  }

  // Lookup names in the parent scope.
  ShadowContextRAII Shadow(Visited);
  lookupInScope(S->getParent(), Result, UDirs);
}

4074private:
VisibleDeclsRecord Visited;
VisibleDeclConsumer &Consumer;
bool IncludeDependentBases;
bool LoadExternal;
4079};
4080} // namespace

4082void Sema::LookupVisibleDecls(Scope *S, LookupNameKind Kind,
                            VisibleDeclConsumer &Consumer,
                            bool IncludeGlobalScope, bool LoadExternal) {
LookupVisibleHelper H(Consumer, /*IncludeDependentBases=*/false,
                      LoadExternal);
H.lookupVisibleDecls(*this, S, Kind, IncludeGlobalScope);
4088}

4090void Sema::LookupVisibleDecls(DeclContext *Ctx, LookupNameKind Kind,
                            VisibleDeclConsumer &Consumer,
                            bool IncludeGlobalScope,
                            bool IncludeDependentBases, bool LoadExternal) {
LookupVisibleHelper H(Consumer, IncludeDependentBases, LoadExternal);
H.lookupVisibleDecls(*this, Ctx, Kind, IncludeGlobalScope);
4096}

4098/// LookupOrCreateLabel - Do a name lookup of a label with the specified name.
4099/// If GnuLabelLoc is a valid source location, then this is a definition
4100/// of an __label__ label name, otherwise it is a normal label definition
4101/// or use.
4102LabelDecl *Sema::LookupOrCreateLabel(IdentifierInfo *II, SourceLocation Loc,
                                   SourceLocation GnuLabelLoc) {
// Do a lookup to see if we have a label with this name already.
NamedDecl *Res = nullptr;

if (GnuLabelLoc.isValid()) {
  // Local label definitions always shadow existing labels.
  Res = LabelDecl::Create(Context, CurContext, Loc, II, GnuLabelLoc);
  Scope *S = CurScope;
  PushOnScopeChains(Res, S, true);
  return cast<LabelDecl>(Res);
}

// Not a GNU local label.
Res = LookupSingleName(CurScope, II, Loc, LookupLabel, NotForRedeclaration);
// If we found a label, check to see if it is in the same context as us.
// When in a Block, we don't want to reuse a label in an enclosing function.
if (Res && Res->getDeclContext() != CurContext)
  Res = nullptr;
if (!Res) {
  // If not forward referenced or defined already, create the backing decl.
  Res = LabelDecl::Create(Context, CurContext, Loc, II);
  Scope *S = CurScope->getFnParent();
  assert(S && "Not in a function?")(static_cast<void> (0));
  PushOnScopeChains(Res, S, true);
}
return cast<LabelDecl>(Res);
4129}

4131//===----------------------------------------------------------------------===//
4132// Typo correction
4133//===----------------------------------------------------------------------===//

4135static bool isCandidateViable(CorrectionCandidateCallback &CCC,
                            TypoCorrection &Candidate) {
Candidate.setCallbackDistance(CCC.RankCandidate(Candidate));
return Candidate.getEditDistance(false) != TypoCorrection::InvalidDistance;
4139}

4141static void LookupPotentialTypoResult(Sema &SemaRef,
                                    LookupResult &Res,
                                    IdentifierInfo *Name,
                                    Scope *S, CXXScopeSpec *SS,
                                    DeclContext *MemberContext,
                                    bool EnteringContext,
                                    bool isObjCIvarLookup,
                                    bool FindHidden);

4150/// Check whether the declarations found for a typo correction are
4151/// visible. Set the correction's RequiresImport flag to true if none of the
4152/// declarations are visible, false otherwise.
4153static void checkCorrectionVisibility(Sema &SemaRef, TypoCorrection &TC) {
TypoCorrection::decl_iterator DI = TC.begin(), DE = TC.end();

for (/**/; DI != DE; ++DI)
  if (!LookupResult::isVisible(SemaRef, *DI))
    break;
// No filtering needed if all decls are visible.
if (DI == DE) {
  TC.setRequiresImport(false);
  return;
}

llvm::SmallVector<NamedDecl*, 4> NewDecls(TC.begin(), DI);
bool AnyVisibleDecls = !NewDecls.empty();

for (/**/; DI != DE; ++DI) {
  if (LookupResult::isVisible(SemaRef, *DI)) {
    if (!AnyVisibleDecls) {
      // Found a visible decl, discard all hidden ones.
      AnyVisibleDecls = true;
      NewDecls.clear();
    }
    NewDecls.push_back(*DI);
  } else if (!AnyVisibleDecls && !(*DI)->isModulePrivate())
    NewDecls.push_back(*DI);
}

if (NewDecls.empty())
  TC = TypoCorrection();
else {
  TC.setCorrectionDecls(NewDecls);
  TC.setRequiresImport(!AnyVisibleDecls);
}
4186}

4188// Fill the supplied vector with the IdentifierInfo pointers for each piece of
4189// the given NestedNameSpecifier (i.e. given a NestedNameSpecifier "foo::bar::",
4190// fill the vector with the IdentifierInfo pointers for "foo" and "bar").
4191static void getNestedNameSpecifierIdentifiers(
  NestedNameSpecifier *NNS,
  SmallVectorImpl<const IdentifierInfo*> &Identifiers) {
if (NestedNameSpecifier *Prefix = NNS->getPrefix())
  getNestedNameSpecifierIdentifiers(Prefix, Identifiers);
else
  Identifiers.clear();

const IdentifierInfo *II = nullptr;

switch (NNS->getKind()) {
case NestedNameSpecifier::Identifier:
  II = NNS->getAsIdentifier();
  break;

case NestedNameSpecifier::Namespace:
  if (NNS->getAsNamespace()->isAnonymousNamespace())
    return;
  II = NNS->getAsNamespace()->getIdentifier();
  break;

case NestedNameSpecifier::NamespaceAlias:
  II = NNS->getAsNamespaceAlias()->getIdentifier();
  break;

case NestedNameSpecifier::TypeSpecWithTemplate:
case NestedNameSpecifier::TypeSpec:
  II = QualType(NNS->getAsType(), 0).getBaseTypeIdentifier();
  break;

case NestedNameSpecifier::Global:
case NestedNameSpecifier::Super:
  return;
}

if (II)
  Identifiers.push_back(II);
4228}

4230void TypoCorrectionConsumer::FoundDecl(NamedDecl *ND, NamedDecl *Hiding,
                                     DeclContext *Ctx, bool InBaseClass) {
// Don't consider hidden names for typo correction.
if (Hiding)
  return;

// Only consider entities with identifiers for names, ignoring
// special names (constructors, overloaded operators, selectors,
// etc.).
IdentifierInfo *Name = ND->getIdentifier();
if (!Name)
  return;

// Only consider visible declarations and declarations from modules with
// names that exactly match.
if (!LookupResult::isVisible(SemaRef, ND) && Name != Typo)
  return;

FoundName(Name->getName());
4249}

4251void TypoCorrectionConsumer::FoundName(StringRef Name) {
// Compute the edit distance between the typo and the name of this
// entity, and add the identifier to the list of results.
addName(Name, nullptr);
4255}

4257void TypoCorrectionConsumer::addKeywordResult(StringRef Keyword) {
// Compute the edit distance between the typo and this keyword,
// and add the keyword to the list of results.
addName(Keyword, nullptr, nullptr, true);
4261}

4263void TypoCorrectionConsumer::addName(StringRef Name, NamedDecl *ND,
                                   NestedNameSpecifier *NNS, bool isKeyword) {
// Use a simple length-based heuristic to determine the minimum possible
// edit distance. If the minimum isn't good enough, bail out early.
StringRef TypoStr = Typo->getName();
unsigned MinED = abs((int)Name.size() - (int)TypoStr.size());
if (MinED && TypoStr.size() / MinED < 3)
  return;

// Compute an upper bound on the allowable edit distance, so that the
// edit-distance algorithm can short-circuit.
unsigned UpperBound = (TypoStr.size() + 2) / 3;
unsigned ED = TypoStr.edit_distance(Name, true, UpperBound);
if (ED > UpperBound) return;

TypoCorrection TC(&SemaRef.Context.Idents.get(Name), ND, NNS, ED);
if (isKeyword) TC.makeKeyword();
TC.setCorrectionRange(nullptr, Result.getLookupNameInfo());
addCorrection(TC);
4282}

4284static const unsigned MaxTypoDistanceResultSets = 5;

4286void TypoCorrectionConsumer::addCorrection(TypoCorrection Correction) {
StringRef TypoStr = Typo->getName();
StringRef Name = Correction.getCorrectionAsIdentifierInfo()->getName();

// For very short typos, ignore potential corrections that have a different
// base identifier from the typo or which have a normalized edit distance
// longer than the typo itself.
if (TypoStr.size() < 3 &&
    (Name != TypoStr || Correction.getEditDistance(true) > TypoStr.size()))
  return;

// If the correction is resolved but is not viable, ignore it.
if (Correction.isResolved()) {
  checkCorrectionVisibility(SemaRef, Correction);
  if (!Correction || !isCandidateViable(*CorrectionValidator, Correction))
    return;
}

TypoResultList &CList =
    CorrectionResults[Correction.getEditDistance(false)][Name];

if (!CList.empty() && !CList.back().isResolved())
  CList.pop_back();
if (NamedDecl *NewND = Correction.getCorrectionDecl()) {
  std::string CorrectionStr = Correction.getAsString(SemaRef.getLangOpts());
  for (TypoResultList::iterator RI = CList.begin(), RIEnd = CList.end();
       RI != RIEnd; ++RI) {
    // If the Correction refers to a decl already in the result list,
    // replace the existing result if the string representation of Correction
    // comes before the current result alphabetically, then stop as there is
    // nothing more to be done to add Correction to the candidate set.
    if (RI->getCorrectionDecl() == NewND) {
      if (CorrectionStr < RI->getAsString(SemaRef.getLangOpts()))
        *RI = Correction;
      return;
    }
  }
}
if (CList.empty() || Correction.isResolved())
  CList.push_back(Correction);

while (CorrectionResults.size() > MaxTypoDistanceResultSets)
  CorrectionResults.erase(std::prev(CorrectionResults.end()));
4329}

4331void TypoCorrectionConsumer::addNamespaces(
  const llvm::MapVector<NamespaceDecl *, bool> &KnownNamespaces) {
SearchNamespaces = true;

for (auto KNPair : KnownNamespaces)
  Namespaces.addNameSpecifier(KNPair.first);

bool SSIsTemplate = false;
if (NestedNameSpecifier *NNS =
        (SS && SS->isValid()) ? SS->getScopeRep() : nullptr) {
  if (const Type *T = NNS->getAsType())
    SSIsTemplate = T->getTypeClass() == Type::TemplateSpecialization;
}
// Do not transform this into an iterator-based loop. The loop body can
// trigger the creation of further types (through lazy deserialization) and
// invalid iterators into this list.
auto &Types = SemaRef.getASTContext().getTypes();
for (unsigned I = 0; I != Types.size(); ++I) {
  const auto *TI = Types[I];
  if (CXXRecordDecl *CD = TI->getAsCXXRecordDecl()) {
    CD = CD->getCanonicalDecl();
    if (!CD->isDependentType() && !CD->isAnonymousStructOrUnion() &&
        !CD->isUnion() && CD->getIdentifier() &&
        (SSIsTemplate || !isa<ClassTemplateSpecializationDecl>(CD)) &&
        (CD->isBeingDefined() || CD->isCompleteDefinition()))
      Namespaces.addNameSpecifier(CD);
  }
}
4359}

4361const TypoCorrection &TypoCorrectionConsumer::getNextCorrection() {
if (++CurrentTCIndex < ValidatedCorrections.size())
  return ValidatedCorrections[CurrentTCIndex];

CurrentTCIndex = ValidatedCorrections.size();
while (!CorrectionResults.empty()) {
  auto DI = CorrectionResults.begin();
  if (DI->second.empty()) {
    CorrectionResults.erase(DI);
    continue;
  }

  auto RI = DI->second.begin();
  if (RI->second.empty()) {
    DI->second.erase(RI);
    performQualifiedLookups();
    continue;
  }

  TypoCorrection TC = RI->second.pop_back_val();
  if (TC.isResolved() || TC.requiresImport() || resolveCorrection(TC)) {
    ValidatedCorrections.push_back(TC);
    return ValidatedCorrections[CurrentTCIndex];
  }
}
return ValidatedCorrections[0];  // The empty correction.
4387}

4389bool TypoCorrectionConsumer::resolveCorrection(TypoCorrection &Candidate) {
IdentifierInfo *Name = Candidate.getCorrectionAsIdentifierInfo();
DeclContext *TempMemberContext = MemberContext;
CXXScopeSpec *TempSS = SS.get();
4393retry_lookup:
LookupPotentialTypoResult(SemaRef, Result, Name, S, TempSS, TempMemberContext,
                          EnteringContext,
                          CorrectionValidator->IsObjCIvarLookup,
                          Name == Typo && !Candidate.WillReplaceSpecifier());
switch (Result.getResultKind()) {
case LookupResult::NotFound:
case LookupResult::NotFoundInCurrentInstantiation:
case LookupResult::FoundUnresolvedValue:
  if (TempSS) {
    // Immediately retry the lookup without the given CXXScopeSpec
    TempSS = nullptr;
    Candidate.WillReplaceSpecifier(true);
    goto retry_lookup;
  }
  if (TempMemberContext) {
    if (SS && !TempSS)
      TempSS = SS.get();
    TempMemberContext = nullptr;
    goto retry_lookup;
  }
  if (SearchNamespaces)
    QualifiedResults.push_back(Candidate);
  break;

case LookupResult::Ambiguous:
  // We don't deal with ambiguities.
  break;

case LookupResult::Found:
case LookupResult::FoundOverloaded:
  // Store all of the Decls for overloaded symbols
  for (auto *TRD : Result)
    Candidate.addCorrectionDecl(TRD);
  checkCorrectionVisibility(SemaRef, Candidate);
  if (!isCandidateViable(*CorrectionValidator, Candidate)) {
    if (SearchNamespaces)
      QualifiedResults.push_back(Candidate);
    break;
  }
  Candidate.setCorrectionRange(SS.get(), Result.getLookupNameInfo());
  return true;
}
return false;
4437}

4439void TypoCorrectionConsumer::performQualifiedLookups() {
unsigned TypoLen = Typo->getName().size();
for (const TypoCorrection &QR : QualifiedResults) {
  for (const auto &NSI : Namespaces) {
    DeclContext *Ctx = NSI.DeclCtx;
    const Type *NSType = NSI.NameSpecifier->getAsType();

    // If the current NestedNameSpecifier refers to a class and the
    // current correction candidate is the name of that class, then skip
    // it as it is unlikely a qualified version of the class' constructor
    // is an appropriate correction.
    if (CXXRecordDecl *NSDecl = NSType ? NSType->getAsCXXRecordDecl() :
                                         nullptr) {
      if (NSDecl->getIdentifier() == QR.getCorrectionAsIdentifierInfo())
        continue;
    }

    TypoCorrection TC(QR);
    TC.ClearCorrectionDecls();
    TC.setCorrectionSpecifier(NSI.NameSpecifier);
    TC.setQualifierDistance(NSI.EditDistance);
    TC.setCallbackDistance(0); // Reset the callback distance

    // If the current correction candidate and namespace combination are
    // too far away from the original typo based on the normalized edit
    // distance, then skip performing a qualified name lookup.
    unsigned TmpED = TC.getEditDistance(true);
    if (QR.getCorrectionAsIdentifierInfo() != Typo && TmpED &&
        TypoLen / TmpED < 3)
      continue;

    Result.clear();
    Result.setLookupName(QR.getCorrectionAsIdentifierInfo());
    if (!SemaRef.LookupQualifiedName(Result, Ctx))
      continue;

    // Any corrections added below will be validated in subsequent
    // iterations of the main while() loop over the Consumer's contents.
    switch (Result.getResultKind()) {
    case LookupResult::Found:
    case LookupResult::FoundOverloaded: {
      if (SS && SS->isValid()) {
        std::string NewQualified = TC.getAsString(SemaRef.getLangOpts());
        std::string OldQualified;
        llvm::raw_string_ostream OldOStream(OldQualified);
        SS->getScopeRep()->print(OldOStream, SemaRef.getPrintingPolicy());
        OldOStream << Typo->getName();
        // If correction candidate would be an identical written qualified
        // identifier, then the existing CXXScopeSpec probably included a
        // typedef that didn't get accounted for properly.
        if (OldOStream.str() == NewQualified)
          break;
      }
      for (LookupResult::iterator TRD = Result.begin(), TRDEnd = Result.end();
           TRD != TRDEnd; ++TRD) {
        if (SemaRef.CheckMemberAccess(TC.getCorrectionRange().getBegin(),
                                      NSType ? NSType->getAsCXXRecordDecl()
                                             : nullptr,
                                      TRD.getPair()) == Sema::AR_accessible)
          TC.addCorrectionDecl(*TRD);
      }
      if (TC.isResolved()) {
        TC.setCorrectionRange(SS.get(), Result.getLookupNameInfo());
        addCorrection(TC);
      }
      break;
    }
    case LookupResult::NotFound:
    case LookupResult::NotFoundInCurrentInstantiation:
    case LookupResult::Ambiguous:
    case LookupResult::FoundUnresolvedValue:
      break;
    }
  }
}
QualifiedResults.clear();
4515}

4517TypoCorrectionConsumer::NamespaceSpecifierSet::NamespaceSpecifierSet(
  ASTContext &Context, DeclContext *CurContext, CXXScopeSpec *CurScopeSpec)
  : Context(Context), CurContextChain(buildContextChain(CurContext)) {
if (NestedNameSpecifier *NNS =
        CurScopeSpec ? CurScopeSpec->getScopeRep() : nullptr) {
  llvm::raw_string_ostream SpecifierOStream(CurNameSpecifier);
  NNS->print(SpecifierOStream, Context.getPrintingPolicy());

  getNestedNameSpecifierIdentifiers(NNS, CurNameSpecifierIdentifiers);
}
// Build the list of identifiers that would be used for an absolute
// (from the global context) NestedNameSpecifier referring to the current
// context.
for (DeclContext *C : llvm::reverse(CurContextChain)) {
  if (auto *ND = dyn_cast_or_null<NamespaceDecl>(C))
    CurContextIdentifiers.push_back(ND->getIdentifier());
}

// Add the global context as a NestedNameSpecifier
SpecifierInfo SI = {cast<DeclContext>(Context.getTranslationUnitDecl()),
                    NestedNameSpecifier::GlobalSpecifier(Context), 1};
DistanceMap[1].push_back(SI);
4539}

4541auto TypoCorrectionConsumer::NamespaceSpecifierSet::buildContextChain(
  DeclContext *Start) -> DeclContextList {
assert(Start && "Building a context chain from a null context")(static_cast<void> (0));
DeclContextList Chain;
for (DeclContext *DC = Start->getPrimaryContext(); DC != nullptr;
     DC = DC->getLookupParent()) {
  NamespaceDecl *ND = dyn_cast_or_null<NamespaceDecl>(DC);
  if (!DC->isInlineNamespace() && !DC->isTransparentContext() &&
      !(ND && ND->isAnonymousNamespace()))
    Chain.push_back(DC->getPrimaryContext());
}
return Chain;
4553}

4555unsigned
4556TypoCorrectionConsumer::NamespaceSpecifierSet::buildNestedNameSpecifier(
  DeclContextList &DeclChain, NestedNameSpecifier *&NNS) {
unsigned NumSpecifiers = 0;
for (DeclContext *C : llvm::reverse(DeclChain)) {
  if (auto *ND = dyn_cast_or_null<NamespaceDecl>(C)) {
    NNS = NestedNameSpecifier::Create(Context, NNS, ND);
    ++NumSpecifiers;
  } else if (auto *RD = dyn_cast_or_null<RecordDecl>(C)) {
    NNS = NestedNameSpecifier::Create(Context, NNS, RD->isTemplateDecl(),
                                      RD->getTypeForDecl());
    ++NumSpecifiers;
  }
}
return NumSpecifiers;
4570}

4572void TypoCorrectionConsumer::NamespaceSpecifierSet::addNameSpecifier(
  DeclContext *Ctx) {
NestedNameSpecifier *NNS = nullptr;
unsigned NumSpecifiers = 0;
DeclContextList NamespaceDeclChain(buildContextChain(Ctx));
DeclContextList FullNamespaceDeclChain(NamespaceDeclChain);

// Eliminate common elements from the two DeclContext chains.
for (DeclContext *C : llvm::reverse(CurContextChain)) {
  if (NamespaceDeclChain.empty() || NamespaceDeclChain.back() != C)
    break;
  NamespaceDeclChain.pop_back();
}

// Build the NestedNameSpecifier from what is left of the NamespaceDeclChain
NumSpecifiers = buildNestedNameSpecifier(NamespaceDeclChain, NNS);

// Add an explicit leading '::' specifier if needed.
if (NamespaceDeclChain.empty()) {
  // Rebuild the NestedNameSpecifier as a globally-qualified specifier.
  NNS = NestedNameSpecifier::GlobalSpecifier(Context);
  NumSpecifiers =
      buildNestedNameSpecifier(FullNamespaceDeclChain, NNS);
} else if (NamedDecl *ND =
               dyn_cast_or_null<NamedDecl>(NamespaceDeclChain.back())) {
  IdentifierInfo *Name = ND->getIdentifier();
  bool SameNameSpecifier = false;
  if (std::find(CurNameSpecifierIdentifiers.begin(),
                CurNameSpecifierIdentifiers.end(),
                Name) != CurNameSpecifierIdentifiers.end()) {
    std::string NewNameSpecifier;
    llvm::raw_string_ostream SpecifierOStream(NewNameSpecifier);
    SmallVector<const IdentifierInfo *, 4> NewNameSpecifierIdentifiers;
    getNestedNameSpecifierIdentifiers(NNS, NewNameSpecifierIdentifiers);
    NNS->print(SpecifierOStream, Context.getPrintingPolicy());
    SpecifierOStream.flush();
    SameNameSpecifier = NewNameSpecifier == CurNameSpecifier;
  }
  if (SameNameSpecifier || llvm::find(CurContextIdentifiers, Name) !=
                               CurContextIdentifiers.end()) {
    // Rebuild the NestedNameSpecifier as a globally-qualified specifier.
    NNS = NestedNameSpecifier::GlobalSpecifier(Context);
    NumSpecifiers =
        buildNestedNameSpecifier(FullNamespaceDeclChain, NNS);
  }
}

// If the built NestedNameSpecifier would be replacing an existing
// NestedNameSpecifier, use the number of component identifiers that
// would need to be changed as the edit distance instead of the number
// of components in the built NestedNameSpecifier.
if (NNS && !CurNameSpecifierIdentifiers.empty()) {
  SmallVector<const IdentifierInfo*, 4> NewNameSpecifierIdentifiers;
  getNestedNameSpecifierIdentifiers(NNS, NewNameSpecifierIdentifiers);
  NumSpecifiers = llvm::ComputeEditDistance(
      llvm::makeArrayRef(CurNameSpecifierIdentifiers),
      llvm::makeArrayRef(NewNameSpecifierIdentifiers));
}

SpecifierInfo SI = {Ctx, NNS, NumSpecifiers};
DistanceMap[NumSpecifiers].push_back(SI);
4633}

4635/// Perform name lookup for a possible result for typo correction.
4636static void LookupPotentialTypoResult(Sema &SemaRef,
                                    LookupResult &Res,
                                    IdentifierInfo *Name,
                                    Scope *S, CXXScopeSpec *SS,
                                    DeclContext *MemberContext,
                                    bool EnteringContext,
                                    bool isObjCIvarLookup,
                                    bool FindHidden) {
Res.suppressDiagnostics();
Res.clear();
Res.setLookupName(Name);
Res.setAllowHidden(FindHidden);
if (MemberContext) {
  if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(MemberContext)) {
    if (isObjCIvarLookup) {
      if (ObjCIvarDecl *Ivar = Class->lookupInstanceVariable(Name)) {
        Res.addDecl(Ivar);
        Res.resolveKind();
        return;
      }
    }

    if (ObjCPropertyDecl *Prop = Class->FindPropertyDeclaration(
            Name, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
      Res.addDecl(Prop);
      Res.resolveKind();
      return;
    }
  }

  SemaRef.LookupQualifiedName(Res, MemberContext);
  return;
}

SemaRef.LookupParsedName(Res, S, SS, /*AllowBuiltinCreation=*/false,
                         EnteringContext);

// Fake ivar lookup; this should really be part of
// LookupParsedName.
if (ObjCMethodDecl *Method = SemaRef.getCurMethodDecl()) {
  if (Method->isInstanceMethod() && Method->getClassInterface() &&
      (Res.empty() ||
       (Res.isSingleResult() &&
        Res.getFoundDecl()->isDefinedOutsideFunctionOrMethod()))) {
     if (ObjCIvarDecl *IV
           = Method->getClassInterface()->lookupInstanceVariable(Name)) {
       Res.addDecl(IV);
       Res.resolveKind();
     }
   }
}
4687}

4689/// Add keywords to the consumer as possible typo corrections.
4690static void AddKeywordsToConsumer(Sema &SemaRef,
                                TypoCorrectionConsumer &Consumer,
                                Scope *S, CorrectionCandidateCallback &CCC,
                                bool AfterNestedNameSpecifier) {
if (AfterNestedNameSpecifier) {
  // For 'X::', we know exactly which keywords can appear next.
  Consumer.addKeywordResult("template");
  if (CCC.WantExpressionKeywords)
    Consumer.addKeywordResult("operator");
  return;
}

if (CCC.WantObjCSuper)
  Consumer.addKeywordResult("super");

if (CCC.WantTypeSpecifiers) {
  // Add type-specifier keywords to the set of results.
  static const char *const CTypeSpecs[] = {
    "char", "const", "double", "enum", "float", "int", "long", "short",
    "signed", "struct", "union", "unsigned", "void", "volatile",
    "_Complex", "_Imaginary",
    // storage-specifiers as well
    "extern", "inline", "static", "typedef"
  };

  const unsigned NumCTypeSpecs = llvm::array_lengthof(CTypeSpecs);
  for (unsigned I = 0; I != NumCTypeSpecs; ++I)
    Consumer.addKeywordResult(CTypeSpecs[I]);

  if (SemaRef.getLangOpts().C99)
    Consumer.addKeywordResult("restrict");
  if (SemaRef.getLangOpts().Bool || SemaRef.getLangOpts().CPlusPlus)
    Consumer.addKeywordResult("bool");
  else if (SemaRef.getLangOpts().C99)
    Consumer.addKeywordResult("_Bool");

  if (SemaRef.getLangOpts().CPlusPlus) {
    Consumer.addKeywordResult("class");
    Consumer.addKeywordResult("typename");
    Consumer.addKeywordResult("wchar_t");

    if (SemaRef.getLangOpts().CPlusPlus11) {
      Consumer.addKeywordResult("char16_t");
      Consumer.addKeywordResult("char32_t");
      Consumer.addKeywordResult("constexpr");
      Consumer.addKeywordResult("decltype");
      Consumer.addKeywordResult("thread_local");
    }
  }

  if (SemaRef.getLangOpts().GNUKeywords)
    Consumer.addKeywordResult("typeof");
} else if (CCC.WantFunctionLikeCasts) {
  static const char *const CastableTypeSpecs[] = {
    "char", "double", "float", "int", "long", "short",
    "signed", "unsigned", "void"
  };
  for (auto *kw : CastableTypeSpecs)
    Consumer.addKeywordResult(kw);
}

if (CCC.WantCXXNamedCasts && SemaRef.getLangOpts().CPlusPlus) {
  Consumer.addKeywordResult("const_cast");
  Consumer.addKeywordResult("dynamic_cast");
  Consumer.addKeywordResult("reinterpret_cast");
  Consumer.addKeywordResult("static_cast");
}

if (CCC.WantExpressionKeywords) {
  Consumer.addKeywordResult("sizeof");
  if (SemaRef.getLangOpts().Bool || SemaRef.getLangOpts().CPlusPlus) {
    Consumer.addKeywordResult("false");
    Consumer.addKeywordResult("true");
  }

  if (SemaRef.getLangOpts().CPlusPlus) {
    static const char *const CXXExprs[] = {
      "delete", "new", "operator", "throw", "typeid"
    };
    const unsigned NumCXXExprs = llvm::array_lengthof(CXXExprs);
    for (unsigned I = 0; I != NumCXXExprs; ++I)
      Consumer.addKeywordResult(CXXExprs[I]);

    if (isa<CXXMethodDecl>(SemaRef.CurContext) &&
        cast<CXXMethodDecl>(SemaRef.CurContext)->isInstance())
      Consumer.addKeywordResult("this");

    if (SemaRef.getLangOpts().CPlusPlus11) {
      Consumer.addKeywordResult("alignof");
      Consumer.addKeywordResult("nullptr");
    }
  }

  if (SemaRef.getLangOpts().C11) {
    // FIXME: We should not suggest _Alignof if the alignof macro
    // is present.
    Consumer.addKeywordResult("_Alignof");
  }
}

if (CCC.WantRemainingKeywords) {
  if (SemaRef.getCurFunctionOrMethodDecl() || SemaRef.getCurBlock()) {
    // Statements.
    static const char *const CStmts[] = {
      "do", "else", "for", "goto", "if", "return", "switch", "while" };
    const unsigned NumCStmts = llvm::array_lengthof(CStmts);
    for (unsigned I = 0; I != NumCStmts; ++I)
      Consumer.addKeywordResult(CStmts[I]);

    if (SemaRef.getLangOpts().CPlusPlus) {
      Consumer.addKeywordResult("catch");
      Consumer.addKeywordResult("try");
    }

    if (S && S->getBreakParent())
      Consumer.addKeywordResult("break");

    if (S && S->getContinueParent())
      Consumer.addKeywordResult("continue");

    if (SemaRef.getCurFunction() &&
        !SemaRef.getCurFunction()->SwitchStack.empty()) {
      Consumer.addKeywordResult("case");
      Consumer.addKeywordResult("default");
    }
  } else {
    if (SemaRef.getLangOpts().CPlusPlus) {
      Consumer.addKeywordResult("namespace");
      Consumer.addKeywordResult("template");
    }

    if (S && S->isClassScope()) {
      Consumer.addKeywordResult("explicit");
      Consumer.addKeywordResult("friend");
      Consumer.addKeywordResult("mutable");
      Consumer.addKeywordResult("private");
      Consumer.addKeywordResult("protected");
      Consumer.addKeywordResult("public");
      Consumer.addKeywordResult("virtual");
    }
  }

  if (SemaRef.getLangOpts().CPlusPlus) {
    Consumer.addKeywordResult("using");

    if (SemaRef.getLangOpts().CPlusPlus11)
      Consumer.addKeywordResult("static_assert");
  }
}
4839}

4841std::unique_ptr<TypoCorrectionConsumer> Sema::makeTypoCorrectionConsumer(
  const DeclarationNameInfo &TypoName, Sema::LookupNameKind LookupKind,
  Scope *S, CXXScopeSpec *SS, CorrectionCandidateCallback &CCC,
  DeclContext *MemberContext, bool EnteringContext,
  const ObjCObjectPointerType *OPT, bool ErrorRecovery) {

if (Diags.hasFatalErrorOccurred() || !getLangOpts().SpellChecking ||
    DisableTypoCorrection)
  return nullptr;

// In Microsoft mode, don't perform typo correction in a template member
// function dependent context because it interferes with the "lookup into
// dependent bases of class templates" feature.
if (getLangOpts().MSVCCompat && CurContext->isDependentContext() &&
    isa<CXXMethodDecl>(CurContext))
  return nullptr;

// We only attempt to correct typos for identifiers.
IdentifierInfo *Typo = TypoName.getName().getAsIdentifierInfo();
if (!Typo)
  return nullptr;

// If the scope specifier itself was invalid, don't try to correct
// typos.
if (SS && SS->isInvalid())
  return nullptr;

// Never try to correct typos during any kind of code synthesis.
if (!CodeSynthesisContexts.empty())
  return nullptr;

// Don't try to correct 'super'.
if (S && S->isInObjcMethodScope() && Typo == getSuperIdentifier())
  return nullptr;

// Abort if typo correction already failed for this specific typo.
IdentifierSourceLocations::iterator locs = TypoCorrectionFailures.find(Typo);
if (locs != TypoCorrectionFailures.end() &&
    locs->second.count(TypoName.getLoc()))
  return nullptr;

// Don't try to correct the identifier "vector" when in AltiVec mode.
// TODO: Figure out why typo correction misbehaves in this case, fix it, and
// remove this workaround.
if ((getLangOpts().AltiVec || getLangOpts().ZVector) && Typo->isStr("vector"))
  return nullptr;

// Provide a stop gap for files that are just seriously broken.  Trying
// to correct all typos can turn into a HUGE performance penalty, causing
// some files to take minutes to get rejected by the parser.
unsigned Limit = getDiagnostics().getDiagnosticOptions().SpellCheckingLimit;
if (Limit && TyposCorrected >= Limit)
  return nullptr;
++TyposCorrected;

// If we're handling a missing symbol error, using modules, and the
// special search all modules option is used, look for a missing import.
if (ErrorRecovery && getLangOpts().Modules &&
    getLangOpts().ModulesSearchAll) {
  // The following has the side effect of loading the missing module.
  getModuleLoader().lookupMissingImports(Typo->getName(),
                                         TypoName.getBeginLoc());
}

// Extend the lifetime of the callback. We delayed this until here
// to avoid allocations in the hot path (which is where no typo correction
// occurs). Note that CorrectionCandidateCallback is polymorphic and
// initially stack-allocated.
std::unique_ptr<CorrectionCandidateCallback> ClonedCCC = CCC.clone();
auto Consumer = std::make_unique<TypoCorrectionConsumer>(
    *this, TypoName, LookupKind, S, SS, std::move(ClonedCCC), MemberContext,
    EnteringContext);

// Perform name lookup to find visible, similarly-named entities.
bool IsUnqualifiedLookup = false;
DeclContext *QualifiedDC = MemberContext;
if (MemberContext) {
  LookupVisibleDecls(MemberContext, LookupKind, *Consumer);

  // Look in qualified interfaces.
  if (OPT) {
    for (auto *I : OPT->quals())
      LookupVisibleDecls(I, LookupKind, *Consumer);
  }
} else if (SS && SS->isSet()) {
  QualifiedDC = computeDeclContext(*SS, EnteringContext);
  if (!QualifiedDC)
    return nullptr;

  LookupVisibleDecls(QualifiedDC, LookupKind, *Consumer);
} else {
  IsUnqualifiedLookup = true;
}

// Determine whether we are going to search in the various namespaces for
// corrections.
bool SearchNamespaces
  = getLangOpts().CPlusPlus &&
    (IsUnqualifiedLookup || (SS && SS->isSet()));

if (IsUnqualifiedLookup || SearchNamespaces) {
  // For unqualified lookup, look through all of the names that we have
  // seen in this translation unit.
  // FIXME: Re-add the ability to skip very unlikely potential corrections.
  for (const auto &I : Context.Idents)
    Consumer->FoundName(I.getKey());

  // Walk through identifiers in external identifier sources.
  // FIXME: Re-add the ability to skip very unlikely potential corrections.
  if (IdentifierInfoLookup *External
                          = Context.Idents.getExternalIdentifierLookup()) {
    std::unique_ptr<IdentifierIterator> Iter(External->getIdentifiers());
    do {
      StringRef Name = Iter->Next();
      if (Name.empty())
        break;

      Consumer->FoundName(Name);
    } while (true);
  }
}

AddKeywordsToConsumer(*this, *Consumer, S,
                      *Consumer->getCorrectionValidator(),
                      SS && SS->isNotEmpty());

// Build the NestedNameSpecifiers for the KnownNamespaces, if we're going
// to search those namespaces.
if (SearchNamespaces) {
  // Load any externally-known namespaces.
  if (ExternalSource && !LoadedExternalKnownNamespaces) {
    SmallVector<NamespaceDecl *, 4> ExternalKnownNamespaces;
    LoadedExternalKnownNamespaces = true;
    ExternalSource->ReadKnownNamespaces(ExternalKnownNamespaces);
    for (auto *N : ExternalKnownNamespaces)
      KnownNamespaces[N] = true;
  }

  Consumer->addNamespaces(KnownNamespaces);
}

return Consumer;
4983}

4985/// Try to "correct" a typo in the source code by finding
4986/// visible declarations whose names are similar to the name that was
4987/// present in the source code.
4988///
4989/// \param TypoName the \c DeclarationNameInfo structure that contains
4990/// the name that was present in the source code along with its location.
4991///
4992/// \param LookupKind the name-lookup criteria used to search for the name.
4993///
4994/// \param S the scope in which name lookup occurs.
4995///
4996/// \param SS the nested-name-specifier that precedes the name we're
4997/// looking for, if present.
4998///
4999/// \param CCC A CorrectionCandidateCallback object that provides further
5000/// validation of typo correction candidates. It also provides flags for
5001/// determining the set of keywords permitted.
5002///
5003/// \param MemberContext if non-NULL, the context in which to look for
5004/// a member access expression.
5005///
5006/// \param EnteringContext whether we're entering the context described by
5007/// the nested-name-specifier SS.
5008///
5009/// \param OPT when non-NULL, the search for visible declarations will
5010/// also walk the protocols in the qualified interfaces of \p OPT.
5011///
5012/// \returns a \c TypoCorrection containing the corrected name if the typo
5013/// along with information such as the \c NamedDecl where the corrected name
5014/// was declared, and any additional \c NestedNameSpecifier needed to access
5015/// it (C++ only). The \c TypoCorrection is empty if there is no correction.
5016TypoCorrection Sema::CorrectTypo(const DeclarationNameInfo &TypoName,
                               Sema::LookupNameKind LookupKind,
                               Scope *S, CXXScopeSpec *SS,
                               CorrectionCandidateCallback &CCC,
                               CorrectTypoKind Mode,
                               DeclContext *MemberContext,
                               bool EnteringContext,
                               const ObjCObjectPointerType *OPT,
                               bool RecordFailure) {
// Always let the ExternalSource have the first chance at correction, even
// if we would otherwise have given up.
if (ExternalSource) {
  if (TypoCorrection Correction =
          ExternalSource->CorrectTypo(TypoName, LookupKind, S, SS, CCC,
                                      MemberContext, EnteringContext, OPT))
    return Correction;
}

// Ugly hack equivalent to CTC == CTC_ObjCMessageReceiver;
// WantObjCSuper is only true for CTC_ObjCMessageReceiver and for
// some instances of CTC_Unknown, while WantRemainingKeywords is true
// for CTC_Unknown but not for CTC_ObjCMessageReceiver.
bool ObjCMessageReceiver = CCC.WantObjCSuper && !CCC.WantRemainingKeywords;

IdentifierInfo *Typo = TypoName.getName().getAsIdentifierInfo();
auto Consumer = makeTypoCorrectionConsumer(TypoName, LookupKind, S, SS, CCC,
                                           MemberContext, EnteringContext,
                                           OPT, Mode == CTK_ErrorRecovery);

if (!Consumer)
  return TypoCorrection();

// If we haven't found anything, we're done.
if (Consumer->empty())
  return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure);

// Make sure the best edit distance (prior to adding any namespace qualifiers)
// is not more that about a third of the length of the typo's identifier.
unsigned ED = Consumer->getBestEditDistance(true);
unsigned TypoLen = Typo->getName().size();
if (ED > 0 && TypoLen / ED < 3)
  return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure);

TypoCorrection BestTC = Consumer->getNextCorrection();
TypoCorrection SecondBestTC = Consumer->getNextCorrection();
if (!BestTC)
  return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure);

ED = BestTC.getEditDistance();

if (TypoLen >= 3 && ED > 0 && TypoLen / ED < 3) {
  // If this was an unqualified lookup and we believe the callback
  // object wouldn't have filtered out possible corrections, note
  // that no correction was found.
  return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure);
}

// If only a single name remains, return that result.
if (!SecondBestTC ||
    SecondBestTC.getEditDistance(false) > BestTC.getEditDistance(false)) {
  const TypoCorrection &Result = BestTC;

  // Don't correct to a keyword that's the same as the typo; the keyword
  // wasn't actually in scope.
  if (ED == 0 && Result.isKeyword())
    return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure);

  TypoCorrection TC = Result;
  TC.setCorrectionRange(SS, TypoName);
  checkCorrectionVisibility(*this, TC);
  return TC;
} else if (SecondBestTC && ObjCMessageReceiver) {
  // Prefer 'super' when we're completing in a message-receiver
  // context.

  if (BestTC.getCorrection().getAsString() != "super") {
    if (SecondBestTC.getCorrection().getAsString() == "super")
      BestTC = SecondBestTC;
    else if ((*Consumer)["super"].front().isKeyword())
      BestTC = (*Consumer)["super"].front();
  }
  // Don't correct to a keyword that's the same as the typo; the keyword
  // wasn't actually in scope.
  if (BestTC.getEditDistance() == 0 ||
      BestTC.getCorrection().getAsString() != "super")
    return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure);

  BestTC.setCorrectionRange(SS, TypoName);
  return BestTC;
}

// Record the failure's location if needed and return an empty correction. If
// this was an unqualified lookup and we believe the callback object did not
// filter out possible corrections, also cache the failure for the typo.
return FailedCorrection(Typo, TypoName.getLoc(), RecordFailure && !SecondBestTC);
5111}

5113/// Try to "correct" a typo in the source code by finding
5114/// visible declarations whose names are similar to the name that was
5115/// present in the source code.
5116///
5117/// \param TypoName the \c DeclarationNameInfo structure that contains
5118/// the name that was present in the source code along with its location.
5119///
5120/// \param LookupKind the name-lookup criteria used to search for the name.
5121///
5122/// \param S the scope in which name lookup occurs.
5123///
5124/// \param SS the nested-name-specifier that precedes the name we're
5125/// looking for, if present.
5126///
5127/// \param CCC A CorrectionCandidateCallback object that provides further
5128/// validation of typo correction candidates. It also provides flags for
5129/// determining the set of keywords permitted.
5130///
5131/// \param TDG A TypoDiagnosticGenerator functor that will be used to print
5132/// diagnostics when the actual typo correction is attempted.
5133///
5134/// \param TRC A TypoRecoveryCallback functor that will be used to build an
5135/// Expr from a typo correction candidate.
5136///
5137/// \param MemberContext if non-NULL, the context in which to look for
5138/// a member access expression.
5139///
5140/// \param EnteringContext whether we're entering the context described by
5141/// the nested-name-specifier SS.
5142///
5143/// \param OPT when non-NULL, the search for visible declarations will
5144/// also walk the protocols in the qualified interfaces of \p OPT.
5145///
5146/// \returns a new \c TypoExpr that will later be replaced in the AST with an
5147/// Expr representing the result of performing typo correction, or nullptr if
5148/// typo correction is not possible. If nullptr is returned, no diagnostics will
5149/// be emitted and it is the responsibility of the caller to emit any that are
5150/// needed.
5151TypoExpr *Sema::CorrectTypoDelayed(
  const DeclarationNameInfo &TypoName, Sema::LookupNameKind LookupKind,
  Scope *S, CXXScopeSpec *SS, CorrectionCandidateCallback &CCC,
  TypoDiagnosticGenerator TDG, TypoRecoveryCallback TRC, CorrectTypoKind Mode,
  DeclContext *MemberContext, bool EnteringContext,
  const ObjCObjectPointerType *OPT) {
auto Consumer = makeTypoCorrectionConsumer(TypoName, LookupKind, S, SS, CCC,
                                           MemberContext, EnteringContext,
                                           OPT, Mode == CTK_ErrorRecovery);

// Give the external sema source a chance to correct the typo.
TypoCorrection ExternalTypo;
if (ExternalSource && Consumer) {
  ExternalTypo = ExternalSource->CorrectTypo(
      TypoName, LookupKind, S, SS, *Consumer->getCorrectionValidator(),
      MemberContext, EnteringContext, OPT);
  if (ExternalTypo)
    Consumer->addCorrection(ExternalTypo);
}

if (!Consumer || Consumer->empty())
  return nullptr;

// Make sure the best edit distance (prior to adding any namespace qualifiers)
// is not more that about a third of the length of the typo's identifier.
unsigned ED = Consumer->getBestEditDistance(true);
IdentifierInfo *Typo = TypoName.getName().getAsIdentifierInfo();
if (!ExternalTypo && ED > 0 && Typo->getName().size() / ED < 3)
  return nullptr;
ExprEvalContexts.back().NumTypos++;
return createDelayedTypo(std::move(Consumer), std::move(TDG), std::move(TRC),
                         TypoName.getLoc());
5183}

5185void TypoCorrection::addCorrectionDecl(NamedDecl *CDecl) {
if (!CDecl) return;

if (isKeyword())
  CorrectionDecls.clear();

CorrectionDecls.push_back(CDecl);

if (!CorrectionName)
  CorrectionName = CDecl->getDeclName();
5195}

5197std::string TypoCorrection::getAsString(const LangOptions &LO) const {
if (CorrectionNameSpec) {
  std::string tmpBuffer;
  llvm::raw_string_ostream PrefixOStream(tmpBuffer);
  CorrectionNameSpec->print(PrefixOStream, PrintingPolicy(LO));
  PrefixOStream << CorrectionName;
  return PrefixOStream.str();
}

return CorrectionName.getAsString();
5207}

5209bool CorrectionCandidateCallback::ValidateCandidate(
  const TypoCorrection &candidate) {
if (!candidate.isResolved())
  return true;

if (candidate.isKeyword())
  return WantTypeSpecifiers || WantExpressionKeywords || WantCXXNamedCasts ||
         WantRemainingKeywords || WantObjCSuper;

bool HasNonType = false;
bool HasStaticMethod = false;
bool HasNonStaticMethod = false;
for (Decl *D : candidate) {
  if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(D))
    D = FTD->getTemplatedDecl();
  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
    if (Method->isStatic())
      HasStaticMethod = true;
    else
      HasNonStaticMethod = true;
  }
  if (!isa<TypeDecl>(D))
    HasNonType = true;
}

if (IsAddressOfOperand && HasNonStaticMethod && !HasStaticMethod &&
    !candidate.getCorrectionSpecifier())
  return false;

return WantTypeSpecifiers || HasNonType;
5239}

5241FunctionCallFilterCCC::FunctionCallFilterCCC(Sema &SemaRef, unsigned NumArgs,
                                           bool HasExplicitTemplateArgs,
                                           MemberExpr *ME)
  : NumArgs(NumArgs), HasExplicitTemplateArgs(HasExplicitTemplateArgs),
    CurContext(SemaRef.CurContext), MemberFn(ME) {
WantTypeSpecifiers = false;
WantFunctionLikeCasts = SemaRef.getLangOpts().CPlusPlus &&
                        !HasExplicitTemplateArgs && NumArgs == 1;
WantCXXNamedCasts = HasExplicitTemplateArgs && NumArgs == 1;
WantRemainingKeywords = false;
5251}

5253bool FunctionCallFilterCCC::ValidateCandidate(const TypoCorrection &candidate) {
if (!candidate.getCorrectionDecl())
  return candidate.isKeyword();

for (auto *C : candidate) {
  FunctionDecl *FD = nullptr;
  NamedDecl *ND = C->getUnderlyingDecl();
  if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(ND))
    FD = FTD->getTemplatedDecl();
  if (!HasExplicitTemplateArgs && !FD) {
    if (!(FD = dyn_cast<FunctionDecl>(ND)) && isa<ValueDecl>(ND)) {
      // If the Decl is neither a function nor a template function,
      // determine if it is a pointer or reference to a function. If so,
      // check against the number of arguments expected for the pointee.
      QualType ValType = cast<ValueDecl>(ND)->getType();
      if (ValType.isNull())
        continue;
      if (ValType->isAnyPointerType() || ValType->isReferenceType())
        ValType = ValType->getPointeeType();
      if (const FunctionProtoType *FPT = ValType->getAs<FunctionProtoType>())
        if (FPT->getNumParams() == NumArgs)
          return true;
    }
  }

  // A typo for a function-style cast can look like a function call in C++.
  if ((HasExplicitTemplateArgs ? getAsTypeTemplateDecl(ND) != nullptr
                               : isa<TypeDecl>(ND)) &&
      CurContext->getParentASTContext().getLangOpts().CPlusPlus)
    // Only a class or class template can take two or more arguments.
    return NumArgs <= 1 || HasExplicitTemplateArgs || isa<CXXRecordDecl>(ND);

  // Skip the current candidate if it is not a FunctionDecl or does not accept
  // the current number of arguments.
  if (!FD || !(FD->getNumParams() >= NumArgs &&
               FD->getMinRequiredArguments() <= NumArgs))
    continue;

  // If the current candidate is a non-static C++ method, skip the candidate
  // unless the method being corrected--or the current DeclContext, if the
  // function being corrected is not a method--is a method in the same class
  // or a descendent class of the candidate's parent class.
  if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
    if (MemberFn || !MD->isStatic()) {
      CXXMethodDecl *CurMD =
          MemberFn
              ? dyn_cast_or_null<CXXMethodDecl>(MemberFn->getMemberDecl())
              : dyn_cast_or_null<CXXMethodDecl>(CurContext);
      CXXRecordDecl *CurRD =
          CurMD ? CurMD->getParent()->getCanonicalDecl() : nullptr;
      CXXRecordDecl *RD = MD->getParent()->getCanonicalDecl();
      if (!CurRD || (CurRD != RD && !CurRD->isDerivedFrom(RD)))
        continue;
    }
  }
  return true;
}
return false;
5311}

5313void Sema::diagnoseTypo(const TypoCorrection &Correction,
                      const PartialDiagnostic &TypoDiag,
                      bool ErrorRecovery) {
diagnoseTypo(Correction, TypoDiag, PDiag(diag::note_previous_decl),
             ErrorRecovery);
5318}

5320/// Find which declaration we should import to provide the definition of
5321/// the given declaration.
5322static NamedDecl *getDefinitionToImport(NamedDecl *D) {
if (VarDecl *VD = dyn_cast<VarDecl>(D))
  return VD->getDefinition();
if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
  return FD->getDefinition();
if (TagDecl *TD = dyn_cast<TagDecl>(D))
  return TD->getDefinition();
// The first definition for this ObjCInterfaceDecl might be in the TU
// and not associated with any module. Use the one we know to be complete
// and have just seen in a module.
if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(D))
  return ID;
if (ObjCProtocolDecl *PD = dyn_cast<ObjCProtocolDecl>(D))
  return PD->getDefinition();
if (TemplateDecl *TD = dyn_cast<TemplateDecl>(D))
  if (NamedDecl *TTD = TD->getTemplatedDecl())
    return getDefinitionToImport(TTD);
return nullptr;
5340}

5342void Sema::diagnoseMissingImport(SourceLocation Loc, NamedDecl *Decl,
                               MissingImportKind MIK, bool Recover) {
// Suggest importing a module providing the definition of this entity, if
// possible.
NamedDecl *Def = getDefinitionToImport(Decl);
if (!Def)
  Def = Decl;

Module *Owner = getOwningModule(Def);
assert(Owner && "definition of hidden declaration is not in a module")(static_cast<void> (0));

llvm::SmallVector<Module*, 8> OwningModules;
OwningModules.push_back(Owner);
auto Merged = Context.getModulesWithMergedDefinition(Def);
OwningModules.insert(OwningModules.end(), Merged.begin(), Merged.end());

diagnoseMissingImport(Loc, Def, Def->getLocation(), OwningModules, MIK,
                      Recover);
5360}

5362/// Get a "quoted.h" or <angled.h> include path to use in a diagnostic
5363/// suggesting the addition of a #include of the specified file.
5364static std::string getHeaderNameForHeader(Preprocessor &PP, const FileEntry *E,
                                        llvm::StringRef IncludingFile) {
bool IsSystem = false;
auto Path = PP.getHeaderSearchInfo().suggestPathToFileForDiagnostics(
    E, IncludingFile, &IsSystem);
return (IsSystem ? '<' : '"') + Path + (IsSystem ? '>' : '"');
5370}

5372void Sema::diagnoseMissingImport(SourceLocation UseLoc, NamedDecl *Decl,
                               SourceLocation DeclLoc,
                               ArrayRef<Module *> Modules,
                               MissingImportKind MIK, bool Recover) {
assert(!Modules.empty())(static_cast<void> (0));

auto NotePrevious = [&] {
  // FIXME: Suppress the note backtrace even under
  // -fdiagnostics-show-note-include-stack. We don't care how this
  // declaration was previously reached.
  Diag(DeclLoc, diag::note_unreachable_entity) << (int)MIK;
};

// Weed out duplicates from module list.
llvm::SmallVector<Module*, 8> UniqueModules;
llvm::SmallDenseSet<Module*, 8> UniqueModuleSet;
for (auto *M : Modules) {
  if (M->Kind == Module::GlobalModuleFragment)
    continue;
  if (UniqueModuleSet.insert(M).second)
    UniqueModules.push_back(M);
}

// Try to find a suitable header-name to #include.
std::string HeaderName;
if (const FileEntry *Header =
        PP.getHeaderToIncludeForDiagnostics(UseLoc, DeclLoc)) {
  if (const FileEntry *FE =
          SourceMgr.getFileEntryForID(SourceMgr.getFileID(UseLoc)))
    HeaderName = getHeaderNameForHeader(PP, Header, FE->tryGetRealPathName());
}

// If we have a #include we should suggest, or if all definition locations
// were in global module fragments, don't suggest an import.
if (!HeaderName.empty() || UniqueModules.empty()) {
  // FIXME: Find a smart place to suggest inserting a #include, and add
  // a FixItHint there.
  Diag(UseLoc, diag::err_module_unimported_use_header)
      << (int)MIK << Decl << !HeaderName.empty() << HeaderName;
  // Produce a note showing where the entity was declared.
  NotePrevious();
  if (Recover)
    createImplicitModuleImportForErrorRecovery(UseLoc, Modules[0]);
  return;
}

Modules = UniqueModules;

if (Modules.size() > 1) {
  std::string ModuleList;
  unsigned N = 0;
  for (Module *M : Modules) {
    ModuleList += "\n        ";
    if (++N == 5 && N != Modules.size()) {
      ModuleList += "[...]";
      break;
    }
    ModuleList += M->getFullModuleName();
  }

  Diag(UseLoc, diag::err_module_unimported_use_multiple)
    << (int)MIK << Decl << ModuleList;
} else {
  // FIXME: Add a FixItHint that imports the corresponding module.
  Diag(UseLoc, diag::err_module_unimported_use)
    << (int)MIK << Decl << Modules[0]->getFullModuleName();
}

NotePrevious();

// Try to recover by implicitly importing this module.
if (Recover)
  createImplicitModuleImportForErrorRecovery(UseLoc, Modules[0]);
5445}

5447/// Diagnose a successfully-corrected typo. Separated from the correction
5448/// itself to allow external validation of the result, etc.
5449///
5450/// \param Correction The result of performing typo correction.
5451/// \param TypoDiag The diagnostic to produce. This will have the corrected
5452///        string added to it (and usually also a fixit).
5453/// \param PrevNote A note to use when indicating the location of the entity to
5454///        which we are correcting. Will have the correction string added to it.
5455/// \param ErrorRecovery If \c true (the default), the caller is going to
5456///        recover from the typo as if the corrected string had been typed.
5457///        In this case, \c PDiag must be an error, and we will attach a fixit
5458///        to it.
5459void Sema::diagnoseTypo(const TypoCorrection &Correction,
                      const PartialDiagnostic &TypoDiag,
                      const PartialDiagnostic &PrevNote,
                      bool ErrorRecovery) {
std::string CorrectedStr = Correction.getAsString(getLangOpts());
std::string CorrectedQuotedStr = Correction.getQuoted(getLangOpts());
FixItHint FixTypo = FixItHint::CreateReplacement(
    Correction.getCorrectionRange(), CorrectedStr);

// Maybe we're just missing a module import.
if (Correction.requiresImport()) {
  NamedDecl *Decl = Correction.getFoundDecl();
  assert(Decl && "import required but no declaration to import")(static_cast<void> (0));

  diagnoseMissingImport(Correction.getCorrectionRange().getBegin(), Decl,
                        MissingImportKind::Declaration, ErrorRecovery);
  return;
}

Diag(Correction.getCorrectionRange().getBegin(), TypoDiag)
  << CorrectedQuotedStr << (ErrorRecovery ? FixTypo : FixItHint());

NamedDecl *ChosenDecl =
    Correction.isKeyword() ? nullptr : Correction.getFoundDecl();
if (PrevNote.getDiagID() && ChosenDecl)
  Diag(ChosenDecl->getLocation(), PrevNote)
    << CorrectedQuotedStr << (ErrorRecovery ? FixItHint() : FixTypo);

// Add any extra diagnostics.
for (const PartialDiagnostic &PD : Correction.getExtraDiagnostics())
  Diag(Correction.getCorrectionRange().getBegin(), PD);
5490}

5492TypoExpr *Sema::createDelayedTypo(std::unique_ptr<TypoCorrectionConsumer> TCC,
                                TypoDiagnosticGenerator TDG,
                                TypoRecoveryCallback TRC,
                                SourceLocation TypoLoc) {
assert(TCC && "createDelayedTypo requires a valid TypoCorrectionConsumer")(static_cast<void> (0));
auto TE = new (Context) TypoExpr(Context.DependentTy, TypoLoc);
auto &State = DelayedTypos[TE];
State.Consumer = std::move(TCC);
State.DiagHandler = std::move(TDG);
State.RecoveryHandler = std::move(TRC);
if (TE)
  TypoExprs.push_back(TE);
return TE;
5505}

5507const Sema::TypoExprState &Sema::getTypoExprState(TypoExpr *TE) const {
auto Entry = DelayedTypos.find(TE);
assert(Entry != DelayedTypos.end() &&(static_cast<void> (0))
       "Failed to get the state for a TypoExpr!")(static_cast<void> (0));
return Entry->second;
5512}

5514void Sema::clearDelayedTypo(TypoExpr *TE) {
DelayedTypos.erase(TE);
5516}

5518void Sema::ActOnPragmaDump(Scope *S, SourceLocation IILoc, IdentifierInfo *II) {
DeclarationNameInfo Name(II, IILoc);
LookupResult R(*this, Name, LookupAnyName, Sema::NotForRedeclaration);
R.suppressDiagnostics();
R.setHideTags(false);
LookupName(R, S);
R.dump();
5525}

←

/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/include/clang/AST/DeclBase.h

1//===- DeclBase.h - Base Classes for representing declarations --*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file defines the Decl and DeclContext interfaces.
10//
11//===----------------------------------------------------------------------===//

13#ifndef LLVM_CLANG_AST_DECLBASE_H
14#define LLVM_CLANG_AST_DECLBASE_H

16#include "clang/AST/ASTDumperUtils.h"
17#include "clang/AST/AttrIterator.h"
18#include "clang/AST/DeclarationName.h"
19#include "clang/Basic/IdentifierTable.h"
20#include "clang/Basic/LLVM.h"
21#include "clang/Basic/SourceLocation.h"
22#include "clang/Basic/Specifiers.h"
23#include "llvm/ADT/ArrayRef.h"
24#include "llvm/ADT/PointerIntPair.h"
25#include "llvm/ADT/PointerUnion.h"
26#include "llvm/ADT/iterator.h"
27#include "llvm/ADT/iterator_range.h"
28#include "llvm/Support/Casting.h"
29#include "llvm/Support/Compiler.h"
30#include "llvm/Support/PrettyStackTrace.h"
31#include "llvm/Support/VersionTuple.h"
32#include <algorithm>
33#include <cassert>
34#include <cstddef>
35#include <iterator>
36#include <string>
37#include <type_traits>
38#include <utility>

40namespace clang {

42class ASTContext;
43class ASTMutationListener;
44class Attr;
45class BlockDecl;
46class DeclContext;
47class ExternalSourceSymbolAttr;
48class FunctionDecl;
49class FunctionType;
50class IdentifierInfo;
51enum Linkage : unsigned char;
52class LinkageSpecDecl;
53class Module;
54class NamedDecl;
55class ObjCCategoryDecl;
56class ObjCCategoryImplDecl;
57class ObjCContainerDecl;
58class ObjCImplDecl;
59class ObjCImplementationDecl;
60class ObjCInterfaceDecl;
61class ObjCMethodDecl;
62class ObjCProtocolDecl;
63struct PrintingPolicy;
64class RecordDecl;
65class SourceManager;
66class Stmt;
67class StoredDeclsMap;
68class TemplateDecl;
69class TemplateParameterList;
70class TranslationUnitDecl;
71class UsingDirectiveDecl;

73/// Captures the result of checking the availability of a
74/// declaration.
75enum AvailabilityResult {
AR_Available = 0,
AR_NotYetIntroduced,
AR_Deprecated,
AR_Unavailable
80};

82/// Decl - This represents one declaration (or definition), e.g. a variable,
83/// typedef, function, struct, etc.
84///
85/// Note: There are objects tacked on before the *beginning* of Decl
86/// (and its subclasses) in its Decl::operator new(). Proper alignment
87/// of all subclasses (not requiring more than the alignment of Decl) is
88/// asserted in DeclBase.cpp.
89class alignas(8) Decl {
90public:
/// Lists the kind of concrete classes of Decl.
enum Kind {
93#define DECL(DERIVED, BASE) DERIVED,
94#define ABSTRACT_DECL(DECL)
95#define DECL_RANGE(BASE, START, END) \
      first##BASE = START, last##BASE = END,
97#define LAST_DECL_RANGE(BASE, START, END) \
      first##BASE = START, last##BASE = END
99#include "clang/AST/DeclNodes.inc"
};

/// A placeholder type used to construct an empty shell of a
/// decl-derived type that will be filled in later (e.g., by some
/// deserialization method).
struct EmptyShell {};

/// IdentifierNamespace - The different namespaces in which
/// declarations may appear.  According to C99 6.2.3, there are
/// four namespaces, labels, tags, members and ordinary
/// identifiers.  C++ describes lookup completely differently:
/// certain lookups merely "ignore" certain kinds of declarations,
/// usually based on whether the declaration is of a type, etc.
///
/// These are meant as bitmasks, so that searches in
/// C++ can look into the "tag" namespace during ordinary lookup.
///
/// Decl currently provides 15 bits of IDNS bits.
enum IdentifierNamespace {
  /// Labels, declared with 'x:' and referenced with 'goto x'.
  IDNS_Label               = 0x0001,

  /// Tags, declared with 'struct foo;' and referenced with
  /// 'struct foo'.  All tags are also types.  This is what
  /// elaborated-type-specifiers look for in C.
  /// This also contains names that conflict with tags in the
  /// same scope but that are otherwise ordinary names (non-type
  /// template parameters and indirect field declarations).
  IDNS_Tag                 = 0x0002,

  /// Types, declared with 'struct foo', typedefs, etc.
  /// This is what elaborated-type-specifiers look for in C++,
  /// but note that it's ill-formed to find a non-tag.
  IDNS_Type                = 0x0004,

  /// Members, declared with object declarations within tag
  /// definitions.  In C, these can only be found by "qualified"
  /// lookup in member expressions.  In C++, they're found by
  /// normal lookup.
  IDNS_Member              = 0x0008,

  /// Namespaces, declared with 'namespace foo {}'.
  /// Lookup for nested-name-specifiers find these.
  IDNS_Namespace           = 0x0010,

  /// Ordinary names.  In C, everything that's not a label, tag,
  /// member, or function-local extern ends up here.
  IDNS_Ordinary            = 0x0020,

  /// Objective C \@protocol.
  IDNS_ObjCProtocol        = 0x0040,

  /// This declaration is a friend function.  A friend function
  /// declaration is always in this namespace but may also be in
  /// IDNS_Ordinary if it was previously declared.
  IDNS_OrdinaryFriend      = 0x0080,

  /// This declaration is a friend class.  A friend class
  /// declaration is always in this namespace but may also be in
  /// IDNS_Tag|IDNS_Type if it was previously declared.
  IDNS_TagFriend           = 0x0100,

  /// This declaration is a using declaration.  A using declaration
  /// *introduces* a number of other declarations into the current
  /// scope, and those declarations use the IDNS of their targets,
  /// but the actual using declarations go in this namespace.
  IDNS_Using               = 0x0200,

  /// This declaration is a C++ operator declared in a non-class
  /// context.  All such operators are also in IDNS_Ordinary.
  /// C++ lexical operator lookup looks for these.
  IDNS_NonMemberOperator   = 0x0400,

  /// This declaration is a function-local extern declaration of a
  /// variable or function. This may also be IDNS_Ordinary if it
  /// has been declared outside any function. These act mostly like
  /// invisible friend declarations, but are also visible to unqualified
  /// lookup within the scope of the declaring function.
  IDNS_LocalExtern         = 0x0800,

  /// This declaration is an OpenMP user defined reduction construction.
  IDNS_OMPReduction        = 0x1000,

  /// This declaration is an OpenMP user defined mapper.
  IDNS_OMPMapper           = 0x2000,
};

/// ObjCDeclQualifier - 'Qualifiers' written next to the return and
/// parameter types in method declarations.  Other than remembering
/// them and mangling them into the method's signature string, these
/// are ignored by the compiler; they are consumed by certain
/// remote-messaging frameworks.
///
/// in, inout, and out are mutually exclusive and apply only to
/// method parameters.  bycopy and byref are mutually exclusive and
/// apply only to method parameters (?).  oneway applies only to
/// results.  All of these expect their corresponding parameter to
/// have a particular type.  None of this is currently enforced by
/// clang.
///
/// This should be kept in sync with ObjCDeclSpec::ObjCDeclQualifier.
enum ObjCDeclQualifier {
  OBJC_TQ_None = 0x0,
  OBJC_TQ_In = 0x1,
  OBJC_TQ_Inout = 0x2,
  OBJC_TQ_Out = 0x4,
  OBJC_TQ_Bycopy = 0x8,
  OBJC_TQ_Byref = 0x10,
  OBJC_TQ_Oneway = 0x20,

  /// The nullability qualifier is set when the nullability of the
  /// result or parameter was expressed via a context-sensitive
  /// keyword.
  OBJC_TQ_CSNullability = 0x40
};

/// The kind of ownership a declaration has, for visibility purposes.
/// This enumeration is designed such that higher values represent higher
/// levels of name hiding.
enum class ModuleOwnershipKind : unsigned {
  /// This declaration is not owned by a module.
  Unowned,

  /// This declaration has an owning module, but is globally visible
  /// (typically because its owning module is visible and we know that
  /// modules cannot later become hidden in this compilation).
  /// After serialization and deserialization, this will be converted
  /// to VisibleWhenImported.
  Visible,

  /// This declaration has an owning module, and is visible when that
  /// module is imported.
  VisibleWhenImported,

  /// This declaration has an owning module, but is only visible to
  /// lookups that occur within that module.
  ModulePrivate
};

239protected:
/// The next declaration within the same lexical
/// DeclContext. These pointers form the linked list that is
/// traversed via DeclContext's decls_begin()/decls_end().
///
/// The extra two bits are used for the ModuleOwnershipKind.
llvm::PointerIntPair<Decl *, 2, ModuleOwnershipKind> NextInContextAndBits;

247private:
friend class DeclContext;

struct MultipleDC {
  DeclContext *SemanticDC;
  DeclContext *LexicalDC;
};

/// DeclCtx - Holds either a DeclContext* or a MultipleDC*.
/// For declarations that don't contain C++ scope specifiers, it contains
/// the DeclContext where the Decl was declared.
/// For declarations with C++ scope specifiers, it contains a MultipleDC*
/// with the context where it semantically belongs (SemanticDC) and the
/// context where it was lexically declared (LexicalDC).
/// e.g.:
///
///   namespace A {
///      void f(); // SemanticDC == LexicalDC == 'namespace A'
///   }
///   void A::f(); // SemanticDC == namespace 'A'
///                // LexicalDC == global namespace
llvm::PointerUnion<DeclContext*, MultipleDC*> DeclCtx;

bool isInSemaDC() const { return DeclCtx.is<DeclContext*>(); }
bool isOutOfSemaDC() const { return DeclCtx.is<MultipleDC*>(); }

MultipleDC *getMultipleDC() const {
  return DeclCtx.get<MultipleDC*>();
}

DeclContext *getSemanticDC() const {
  return DeclCtx.get<DeclContext*>();
}

/// Loc - The location of this decl.
SourceLocation Loc;

/// DeclKind - This indicates which class this is.
unsigned DeclKind : 7;

/// InvalidDecl - This indicates a semantic error occurred.
unsigned InvalidDecl :  1;

/// HasAttrs - This indicates whether the decl has attributes or not.
unsigned HasAttrs : 1;

/// Implicit - Whether this declaration was implicitly generated by
/// the implementation rather than explicitly written by the user.
unsigned Implicit : 1;

/// Whether this declaration was "used", meaning that a definition is
/// required.
unsigned Used : 1;

/// Whether this declaration was "referenced".
/// The difference with 'Used' is whether the reference appears in a
/// evaluated context or not, e.g. functions used in uninstantiated templates
/// are regarded as "referenced" but not "used".
unsigned Referenced : 1;

/// Whether this declaration is a top-level declaration (function,
/// global variable, etc.) that is lexically inside an objc container
/// definition.
unsigned TopLevelDeclInObjCContainer : 1;

/// Whether statistic collection is enabled.
static bool StatisticsEnabled;

315protected:
friend class ASTDeclReader;
friend class ASTDeclWriter;
friend class ASTNodeImporter;
friend class ASTReader;
friend class CXXClassMemberWrapper;
friend class LinkageComputer;
template<typename decl_type> friend class Redeclarable;

/// Access - Used by C++ decls for the access specifier.
// NOTE: VC++ treats enums as signed, avoid using the AccessSpecifier enum
unsigned Access : 2;

/// Whether this declaration was loaded from an AST file.
unsigned FromASTFile : 1;

/// IdentifierNamespace - This specifies what IDNS_* namespace this lives in.
unsigned IdentifierNamespace : 14;

/// If 0, we have not computed the linkage of this declaration.
/// Otherwise, it is the linkage + 1.
mutable unsigned CacheValidAndLinkage : 3;

/// Allocate memory for a deserialized declaration.
///
/// This routine must be used to allocate memory for any declaration that is
/// deserialized from a module file.
///
/// \param Size The size of the allocated object.
/// \param Ctx The context in which we will allocate memory.
/// \param ID The global ID of the deserialized declaration.
/// \param Extra The amount of extra space to allocate after the object.
void *operator new(std::size_t Size, const ASTContext &Ctx, unsigned ID,
                   std::size_t Extra = 0);

/// Allocate memory for a non-deserialized declaration.
void *operator new(std::size_t Size, const ASTContext &Ctx,
                   DeclContext *Parent, std::size_t Extra = 0);

354private:
bool AccessDeclContextSanity() const;

/// Get the module ownership kind to use for a local lexical child of \p DC,
/// which may be either a local or (rarely) an imported declaration.
static ModuleOwnershipKind getModuleOwnershipKindForChildOf(DeclContext *DC) {
  if (DC) {
    auto *D = cast<Decl>(DC);
    auto MOK = D->getModuleOwnershipKind();
    if (MOK != ModuleOwnershipKind::Unowned &&
        (!D->isFromASTFile() || D->hasLocalOwningModuleStorage()))
      return MOK;
    // If D is not local and we have no local module storage, then we don't
    // need to track module ownership at all.
  }
  return ModuleOwnershipKind::Unowned;
}

372public:
Decl() = delete;
Decl(const Decl&) = delete;
Decl(Decl &&) = delete;
Decl &operator=(const Decl&) = delete;
Decl &operator=(Decl&&) = delete;

379protected:
Decl(Kind DK, DeclContext *DC, SourceLocation L)
    : NextInContextAndBits(nullptr, getModuleOwnershipKindForChildOf(DC)),
      DeclCtx(DC), Loc(L), DeclKind(DK), InvalidDecl(false), HasAttrs(false),
      Implicit(false), Used(false), Referenced(false),
      TopLevelDeclInObjCContainer(false), Access(AS_none), FromASTFile(0),
      IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
      CacheValidAndLinkage(0) {
  if (StatisticsEnabled) add(DK);
}

Decl(Kind DK, EmptyShell Empty)
    : DeclKind(DK), InvalidDecl(false), HasAttrs(false), Implicit(false),
      Used(false), Referenced(false), TopLevelDeclInObjCContainer(false),
      Access(AS_none), FromASTFile(0),
      IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
      CacheValidAndLinkage(0) {
  if (StatisticsEnabled) add(DK);
}

virtual ~Decl();

/// Update a potentially out-of-date declaration.
void updateOutOfDate(IdentifierInfo &II) const;

Linkage getCachedLinkage() const {
  return Linkage(CacheValidAndLinkage - 1);
}

void setCachedLinkage(Linkage L) const {
  CacheValidAndLinkage = L + 1;
}

bool hasCachedLinkage() const {
  return CacheValidAndLinkage;
}

416public:
/// Source range that this declaration covers.
virtual SourceRange getSourceRange() const LLVM_READONLY__attribute__((__pure__)) {
  return SourceRange(getLocation(), getLocation());
}

SourceLocation getBeginLoc() const LLVM_READONLY__attribute__((__pure__)) {
  return getSourceRange().getBegin();
}

SourceLocation getEndLoc() const LLVM_READONLY__attribute__((__pure__)) {
  return getSourceRange().getEnd();
}

SourceLocation getLocation() const { return Loc; }
void setLocation(SourceLocation L) { Loc = L; }

Kind getKind() const { return static_cast<Kind>(DeclKind); }
const char *getDeclKindName() const;

Decl *getNextDeclInContext() { return NextInContextAndBits.getPointer(); }
const Decl *getNextDeclInContext() const {return NextInContextAndBits.getPointer();}

DeclContext *getDeclContext() {
  if (isInSemaDC())
    return getSemanticDC();
  return getMultipleDC()->SemanticDC;
}
const DeclContext *getDeclContext() const {
  return const_cast<Decl*>(this)->getDeclContext();
}

/// Find the innermost non-closure ancestor of this declaration,
/// walking up through blocks, lambdas, etc.  If that ancestor is
/// not a code context (!isFunctionOrMethod()), returns null.
///
/// A declaration may be its own non-closure context.
Decl *getNonClosureContext();
const Decl *getNonClosureContext() const {
  return const_cast<Decl*>(this)->getNonClosureContext();
}

TranslationUnitDecl *getTranslationUnitDecl();
const TranslationUnitDecl *getTranslationUnitDecl() const {
  return const_cast<Decl*>(this)->getTranslationUnitDecl();
}

bool isInAnonymousNamespace() const;

bool isInStdNamespace() const;

ASTContext &getASTContext() const LLVM_READONLY__attribute__((__pure__));

/// Helper to get the language options from the ASTContext.
/// Defined out of line to avoid depending on ASTContext.h.
const LangOptions &getLangOpts() const LLVM_READONLY__attribute__((__pure__));

void setAccess(AccessSpecifier AS) {
  Access = AS;
  assert(AccessDeclContextSanity())(static_cast<void> (0));
}

AccessSpecifier getAccess() const {
  assert(AccessDeclContextSanity())(static_cast<void> (0));
  return AccessSpecifier(Access);
}

/// Retrieve the access specifier for this declaration, even though
/// it may not yet have been properly set.
AccessSpecifier getAccessUnsafe() const {
  return AccessSpecifier(Access);
}

bool hasAttrs() const { return HasAttrs; }

void setAttrs(const AttrVec& Attrs) {
  return setAttrsImpl(Attrs, getASTContext());
}

AttrVec &getAttrs() {
  return const_cast<AttrVec&>(const_cast<const Decl*>(this)->getAttrs());
}

const AttrVec &getAttrs() const;
void dropAttrs();
void addAttr(Attr *A);

using attr_iterator = AttrVec::const_iterator;
using attr_range = llvm::iterator_range<attr_iterator>;

attr_range attrs() const {
  return attr_range(attr_begin(), attr_end());
}

attr_iterator attr_begin() const {
  return hasAttrs() ? getAttrs().begin() : nullptr;
}
attr_iterator attr_end() const {
  return hasAttrs() ? getAttrs().end() : nullptr;
}

template <typename T>
void dropAttr() {
  if (!HasAttrs) return;

  AttrVec &Vec = getAttrs();
  llvm::erase_if(Vec, [](Attr *A) { return isa<T>(A); });

  if (Vec.empty())
    HasAttrs = false;
}

template <typename T>
llvm::iterator_range<specific_attr_iterator<T>> specific_attrs() const {
  return llvm::make_range(specific_attr_begin<T>(), specific_attr_end<T>());
}

template <typename T>
specific_attr_iterator<T> specific_attr_begin() const {
  return specific_attr_iterator<T>(attr_begin());
}

template <typename T>
specific_attr_iterator<T> specific_attr_end() const {
  return specific_attr_iterator<T>(attr_end());
}

template<typename T> T *getAttr() const {
  return hasAttrs() ? getSpecificAttr<T>(getAttrs()) : nullptr;
}

template<typename T> bool hasAttr() const {
  return hasAttrs() && hasSpecificAttr<T>(getAttrs());
}

/// getMaxAlignment - return the maximum alignment specified by attributes
/// on this decl, 0 if there are none.
unsigned getMaxAlignment() const;

/// setInvalidDecl - Indicates the Decl had a semantic error. This
/// allows for graceful error recovery.
void setInvalidDecl(bool Invalid = true);
bool isInvalidDecl() const { return (bool) InvalidDecl; }

/// isImplicit - Indicates whether the declaration was implicitly
/// generated by the implementation. If false, this declaration
/// was written explicitly in the source code.
bool isImplicit() const { return Implicit; }
void setImplicit(bool I = true) { Implicit = I; }

/// Whether *any* (re-)declaration of the entity was used, meaning that
/// a definition is required.
///
/// \param CheckUsedAttr When true, also consider the "used" attribute
/// (in addition to the "used" bit set by \c setUsed()) when determining
/// whether the function is used.
bool isUsed(bool CheckUsedAttr = true) const;

/// Set whether the declaration is used, in the sense of odr-use.
///
/// This should only be used immediately after creating a declaration.
/// It intentionally doesn't notify any listeners.
void setIsUsed() { getCanonicalDecl()->Used = true; }

/// Mark the declaration used, in the sense of odr-use.
///
/// This notifies any mutation listeners in addition to setting a bit
/// indicating the declaration is used.
void markUsed(ASTContext &C);

/// Whether any declaration of this entity was referenced.
bool isReferenced() const;

/// Whether this declaration was referenced. This should not be relied
/// upon for anything other than debugging.
bool isThisDeclarationReferenced() const { return Referenced; }

void setReferenced(bool R = true) { Referenced = R; }

/// Whether this declaration is a top-level declaration (function,
/// global variable, etc.) that is lexically inside an objc container
/// definition.
bool isTopLevelDeclInObjCContainer() const {
  return TopLevelDeclInObjCContainer;
}

void setTopLevelDeclInObjCContainer(bool V = true) {
  TopLevelDeclInObjCContainer = V;
}

/// Looks on this and related declarations for an applicable
/// external source symbol attribute.
ExternalSourceSymbolAttr *getExternalSourceSymbolAttr() const;

/// Whether this declaration was marked as being private to the
/// module in which it was defined.
bool isModulePrivate() const {
  return getModuleOwnershipKind() == ModuleOwnershipKind::ModulePrivate;
}

/// Return true if this declaration has an attribute which acts as
/// definition of the entity, such as 'alias' or 'ifunc'.
bool hasDefiningAttr() const;

/// Return this declaration's defining attribute if it has one.
const Attr *getDefiningAttr() const;

623protected:
/// Specify that this declaration was marked as being private
/// to the module in which it was defined.
void setModulePrivate() {
  // The module-private specifier has no effect on unowned declarations.
  // FIXME: We should track this in some way for source fidelity.
  if (getModuleOwnershipKind() == ModuleOwnershipKind::Unowned)
    return;
  setModuleOwnershipKind(ModuleOwnershipKind::ModulePrivate);
}

634public:
/// Set the FromASTFile flag. This indicates that this declaration
/// was deserialized and not parsed from source code and enables
/// features such as module ownership information.
void setFromASTFile() {
  FromASTFile = true;
}

/// Set the owning module ID.  This may only be called for
/// deserialized Decls.
void setOwningModuleID(unsigned ID) {
  assert(isFromASTFile() && "Only works on a deserialized declaration")(static_cast<void> (0));
  *((unsigned*)this - 2) = ID;
}

649public:
/// Determine the availability of the given declaration.
///
/// This routine will determine the most restrictive availability of
/// the given declaration (e.g., preferring 'unavailable' to
/// 'deprecated').
///
/// \param Message If non-NULL and the result is not \c
/// AR_Available, will be set to a (possibly empty) message
/// describing why the declaration has not been introduced, is
/// deprecated, or is unavailable.
///
/// \param EnclosingVersion The version to compare with. If empty, assume the
/// deployment target version.
///
/// \param RealizedPlatform If non-NULL and the availability result is found
/// in an available attribute it will set to the platform which is written in
/// the available attribute.
AvailabilityResult
getAvailability(std::string *Message = nullptr,
                VersionTuple EnclosingVersion = VersionTuple(),
                StringRef *RealizedPlatform = nullptr) const;

/// Retrieve the version of the target platform in which this
/// declaration was introduced.
///
/// \returns An empty version tuple if this declaration has no 'introduced'
/// availability attributes, or the version tuple that's specified in the
/// attribute otherwise.
VersionTuple getVersionIntroduced() const;

/// Determine whether this declaration is marked 'deprecated'.
///
/// \param Message If non-NULL and the declaration is deprecated,
/// this will be set to the message describing why the declaration
/// was deprecated (which may be empty).
bool isDeprecated(std::string *Message = nullptr) const {
  return getAvailability(Message) == AR_Deprecated;
}

/// Determine whether this declaration is marked 'unavailable'.
///
/// \param Message If non-NULL and the declaration is unavailable,
/// this will be set to the message describing why the declaration
/// was made unavailable (which may be empty).
bool isUnavailable(std::string *Message = nullptr) const {
  return getAvailability(Message) == AR_Unavailable;
}

/// Determine whether this is a weak-imported symbol.
///
/// Weak-imported symbols are typically marked with the
/// 'weak_import' attribute, but may also be marked with an
/// 'availability' attribute where we're targing a platform prior to
/// the introduction of this feature.
bool isWeakImported() const;

/// Determines whether this symbol can be weak-imported,
/// e.g., whether it would be well-formed to add the weak_import
/// attribute.
///
/// \param IsDefinition Set to \c true to indicate that this
/// declaration cannot be weak-imported because it has a definition.
bool canBeWeakImported(bool &IsDefinition) const;

/// Determine whether this declaration came from an AST file (such as
/// a precompiled header or module) rather than having been parsed.
bool isFromASTFile() const { return FromASTFile; }

/// Retrieve the global declaration ID associated with this
/// declaration, which specifies where this Decl was loaded from.
unsigned getGlobalID() const {
  if (isFromASTFile())
    return *((const unsigned*)this - 1);
  return 0;
}

/// Retrieve the global ID of the module that owns this particular
/// declaration.
unsigned getOwningModuleID() const {
  if (isFromASTFile())
    return *((const unsigned*)this - 2);
  return 0;
}

734private:
Module *getOwningModuleSlow() const;

737protected:
bool hasLocalOwningModuleStorage() const;

740public:
/// Get the imported owning module, if this decl is from an imported
/// (non-local) module.
Module *getImportedOwningModule() const {
  if (!isFromASTFile() || !hasOwningModule())
    return nullptr;

  return getOwningModuleSlow();
}

/// Get the local owning module, if known. Returns nullptr if owner is
/// not yet known or declaration is not from a module.
Module *getLocalOwningModule() const {
  if (isFromASTFile() || !hasOwningModule())
    return nullptr;

  assert(hasLocalOwningModuleStorage() &&(static_cast<void> (0))
         "owned local decl but no local module storage")(static_cast<void> (0));
  return reinterpret_cast<Module *const *>(this)[-1];
}
void setLocalOwningModule(Module *M) {
  assert(!isFromASTFile() && hasOwningModule() &&(static_cast<void> (0))
         hasLocalOwningModuleStorage() &&(static_cast<void> (0))
         "should not have a cached owning module")(static_cast<void> (0));
  reinterpret_cast<Module **>(this)[-1] = M;
}

/// Is this declaration owned by some module?
bool hasOwningModule() const {
  return getModuleOwnershipKind() != ModuleOwnershipKind::Unowned;
}

/// Get the module that owns this declaration (for visibility purposes).
Module *getOwningModule() const {
  return isFromASTFile() ? getImportedOwningModule() : getLocalOwningModule();
}

/// Get the module that owns this declaration for linkage purposes.
/// There only ever is such a module under the C++ Modules TS.
///
/// \param IgnoreLinkage Ignore the linkage of the entity; assume that
/// all declarations in a global module fragment are unowned.
Module *getOwningModuleForLinkage(bool IgnoreLinkage = false) const;

/// Determine whether this declaration is definitely visible to name lookup,
/// independent of whether the owning module is visible.
/// Note: The declaration may be visible even if this returns \c false if the
/// owning module is visible within the query context. This is a low-level
/// helper function; most code should be calling Sema::isVisible() instead.
bool isUnconditionallyVisible() const {
  return (int)getModuleOwnershipKind() <= (int)ModuleOwnershipKind::Visible;
}

/// Set that this declaration is globally visible, even if it came from a
/// module that is not visible.
void setVisibleDespiteOwningModule() {
  if (!isUnconditionallyVisible())
    setModuleOwnershipKind(ModuleOwnershipKind::Visible);
}

/// Get the kind of module ownership for this declaration.
ModuleOwnershipKind getModuleOwnershipKind() const {
  return NextInContextAndBits.getInt();
}

/// Set whether this declaration is hidden from name lookup.
void setModuleOwnershipKind(ModuleOwnershipKind MOK) {
  assert(!(getModuleOwnershipKind() == ModuleOwnershipKind::Unowned &&(static_cast<void> (0))
           MOK != ModuleOwnershipKind::Unowned && !isFromASTFile() &&(static_cast<void> (0))
           !hasLocalOwningModuleStorage()) &&(static_cast<void> (0))
         "no storage available for owning module for this declaration")(static_cast<void> (0));
  NextInContextAndBits.setInt(MOK);
}

unsigned getIdentifierNamespace() const {
  return IdentifierNamespace;
}

bool isInIdentifierNamespace(unsigned NS) const {
  return getIdentifierNamespace() & NS;
}

static unsigned getIdentifierNamespaceForKind(Kind DK);

bool hasTagIdentifierNamespace() const {
  return isTagIdentifierNamespace(getIdentifierNamespace());
}

static bool isTagIdentifierNamespace(unsigned NS) {
  // TagDecls have Tag and Type set and may also have TagFriend.
  return (NS & ~IDNS_TagFriend) == (IDNS_Tag | IDNS_Type);
}

/// getLexicalDeclContext - The declaration context where this Decl was
/// lexically declared (LexicalDC). May be different from
/// getDeclContext() (SemanticDC).
/// e.g.:
///
///   namespace A {
///      void f(); // SemanticDC == LexicalDC == 'namespace A'
///   }
///   void A::f(); // SemanticDC == namespace 'A'
///                // LexicalDC == global namespace
DeclContext *getLexicalDeclContext() {
  if (isInSemaDC())
    return getSemanticDC();
  return getMultipleDC()->LexicalDC;
}
const DeclContext *getLexicalDeclContext() const {
  return const_cast<Decl*>(this)->getLexicalDeclContext();
}

/// Determine whether this declaration is declared out of line (outside its
/// semantic context).
virtual bool isOutOfLine() const;

/// setDeclContext - Set both the semantic and lexical DeclContext
/// to DC.
void setDeclContext(DeclContext *DC);

void setLexicalDeclContext(DeclContext *DC);

/// Determine whether this declaration is a templated entity (whether it is
// within the scope of a template parameter).
bool isTemplated() const;

/// Determine the number of levels of template parameter surrounding this
/// declaration.
unsigned getTemplateDepth() const;

/// isDefinedOutsideFunctionOrMethod - This predicate returns true if this
/// scoped decl is defined outside the current function or method.  This is
/// roughly global variables and functions, but also handles enums (which
/// could be defined inside or outside a function etc).
bool isDefinedOutsideFunctionOrMethod() const {
  return getParentFunctionOrMethod() == nullptr;
}

/// Determine whether a substitution into this declaration would occur as
/// part of a substitution into a dependent local scope. Such a substitution
/// transitively substitutes into all constructs nested within this
/// declaration.
///
/// This recognizes non-defining declarations as well as members of local
/// classes and lambdas:
/// \code
///     template<typename T> void foo() { void bar(); }
///     template<typename T> void foo2() { class ABC { void bar(); }; }
///     template<typename T> inline int x = [](){ return 0; }();
/// \endcode
bool isInLocalScopeForInstantiation() const;

/// If this decl is defined inside a function/method/block it returns
/// the corresponding DeclContext, otherwise it returns null.
const DeclContext *getParentFunctionOrMethod() const;
DeclContext *getParentFunctionOrMethod() {
  return const_cast<DeclContext*>(
                  const_cast<const Decl*>(this)->getParentFunctionOrMethod());
}

/// Retrieves the "canonical" declaration of the given declaration.
virtual Decl *getCanonicalDecl() { return this; }
const Decl *getCanonicalDecl() const {
  return const_cast<Decl*>(this)->getCanonicalDecl();
}

/// Whether this particular Decl is a canonical one.
bool isCanonicalDecl() const { return getCanonicalDecl() == this; }

909protected:
/// Returns the next redeclaration or itself if this is the only decl.
///
/// Decl subclasses that can be redeclared should override this method so that
/// Decl::redecl_iterator can iterate over them.
virtual Decl *getNextRedeclarationImpl() { return this; }

/// Implementation of getPreviousDecl(), to be overridden by any
/// subclass that has a redeclaration chain.
virtual Decl *getPreviousDeclImpl() { return nullptr; }

/// Implementation of getMostRecentDecl(), to be overridden by any
/// subclass that has a redeclaration chain.
virtual Decl *getMostRecentDeclImpl() { return this; }

924public:
/// Iterates through all the redeclarations of the same decl.
class redecl_iterator {
  /// Current - The current declaration.
  Decl *Current = nullptr;
  Decl *Starter;

public:
  using value_type = Decl *;
  using reference = const value_type &;
  using pointer = const value_type *;
  using iterator_category = std::forward_iterator_tag;
  using difference_type = std::ptrdiff_t;

  redecl_iterator() = default;
  explicit redecl_iterator(Decl *C) : Current(C), Starter(C) {}

  reference operator*() const { return Current; }
  value_type operator->() const { return Current; }

  redecl_iterator& operator++() {
    assert(Current && "Advancing while iterator has reached end")(static_cast<void> (0));
    // Get either previous decl or latest decl.
    Decl *Next = Current->getNextRedeclarationImpl();
    assert(Next && "Should return next redeclaration or itself, never null!")(static_cast<void> (0));
    Current = (Next != Starter) ? Next : nullptr;
    return *this;
  }

  redecl_iterator operator++(int) {
    redecl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(redecl_iterator x, redecl_iterator y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(redecl_iterator x, redecl_iterator y) {
    return x.Current != y.Current;
  }
};

using redecl_range = llvm::iterator_range<redecl_iterator>;

/// Returns an iterator range for all the redeclarations of the same
/// decl. It will iterate at least once (when this decl is the only one).
redecl_range redecls() const {
  return redecl_range(redecls_begin(), redecls_end());
}

redecl_iterator redecls_begin() const {
  return redecl_iterator(const_cast<Decl *>(this));
}

redecl_iterator redecls_end() const { return redecl_iterator(); }

/// Retrieve the previous declaration that declares the same entity
/// as this declaration, or NULL if there is no previous declaration.
Decl *getPreviousDecl() { return getPreviousDeclImpl(); }

/// Retrieve the previous declaration that declares the same entity
/// as this declaration, or NULL if there is no previous declaration.
const Decl *getPreviousDecl() const {
  return const_cast<Decl *>(this)->getPreviousDeclImpl();
}

/// True if this is the first declaration in its redeclaration chain.
bool isFirstDecl() const {
  return getPreviousDecl() == nullptr;
}

/// Retrieve the most recent declaration that declares the same entity
/// as this declaration (which may be this declaration).
Decl *getMostRecentDecl() { return getMostRecentDeclImpl(); }

/// Retrieve the most recent declaration that declares the same entity
/// as this declaration (which may be this declaration).
const Decl *getMostRecentDecl() const {
  return const_cast<Decl *>(this)->getMostRecentDeclImpl();
}

/// getBody - If this Decl represents a declaration for a body of code,
///  such as a function or method definition, this method returns the
///  top-level Stmt* of that body.  Otherwise this method returns null.
virtual Stmt* getBody() const { return nullptr; }

/// Returns true if this \c Decl represents a declaration for a body of
/// code, such as a function or method definition.
/// Note that \c hasBody can also return true if any redeclaration of this
/// \c Decl represents a declaration for a body of code.
virtual bool hasBody() const { return getBody() != nullptr; }

/// getBodyRBrace - Gets the right brace of the body, if a body exists.
/// This works whether the body is a CompoundStmt or a CXXTryStmt.
SourceLocation getBodyRBrace() const;

// global temp stats (until we have a per-module visitor)
static void add(Kind k);
static void EnableStatistics();
static void PrintStats();

/// isTemplateParameter - Determines whether this declaration is a
/// template parameter.
bool isTemplateParameter() const;

/// isTemplateParameter - Determines whether this declaration is a
/// template parameter pack.
bool isTemplateParameterPack() const;

/// Whether this declaration is a parameter pack.
bool isParameterPack() const;

/// returns true if this declaration is a template
bool isTemplateDecl() const;

/// Whether this declaration is a function or function template.
bool isFunctionOrFunctionTemplate() const {
  return (DeclKind >= Decl::firstFunction &&
          DeclKind <= Decl::lastFunction) ||
         DeclKind == FunctionTemplate;
}

/// If this is a declaration that describes some template, this
/// method returns that template declaration.
///
/// Note that this returns nullptr for partial specializations, because they
/// are not modeled as TemplateDecls. Use getDescribedTemplateParams to handle
/// those cases.
TemplateDecl *getDescribedTemplate() const;

/// If this is a declaration that describes some template or partial
/// specialization, this returns the corresponding template parameter list.
const TemplateParameterList *getDescribedTemplateParams() const;

/// Returns the function itself, or the templated function if this is a
/// function template.
FunctionDecl *getAsFunction() LLVM_READONLY__attribute__((__pure__));

const FunctionDecl *getAsFunction() const {
  return const_cast<Decl *>(this)->getAsFunction();
}

/// Changes the namespace of this declaration to reflect that it's
/// a function-local extern declaration.
///
/// These declarations appear in the lexical context of the extern
/// declaration, but in the semantic context of the enclosing namespace
/// scope.
void setLocalExternDecl() {
  Decl *Prev = getPreviousDecl();
  IdentifierNamespace &= ~IDNS_Ordinary;

  // It's OK for the declaration to still have the "invisible friend" flag or
  // the "conflicts with tag declarations in this scope" flag for the outer
  // scope.
  assert((IdentifierNamespace & ~(IDNS_OrdinaryFriend | IDNS_Tag)) == 0 &&(static_cast<void> (0))
         "namespace is not ordinary")(static_cast<void> (0));

  IdentifierNamespace |= IDNS_LocalExtern;
  if (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary)
    IdentifierNamespace |= IDNS_Ordinary;
}

/// Determine whether this is a block-scope declaration with linkage.
/// This will either be a local variable declaration declared 'extern', or a
/// local function declaration.
bool isLocalExternDecl() {
  return IdentifierNamespace & IDNS_LocalExtern;
}

/// Changes the namespace of this declaration to reflect that it's
/// the object of a friend declaration.
///
/// These declarations appear in the lexical context of the friending
/// class, but in the semantic context of the actual entity.  This property
/// applies only to a specific decl object;  other redeclarations of the
/// same entity may not (and probably don't) share this property.
void setObjectOfFriendDecl(bool PerformFriendInjection = false) {
  unsigned OldNS = IdentifierNamespace;
  assert((OldNS & (IDNS_Tag | IDNS_Ordinary |(static_cast<void> (0))
                   IDNS_TagFriend | IDNS_OrdinaryFriend |(static_cast<void> (0))
                   IDNS_LocalExtern | IDNS_NonMemberOperator)) &&(static_cast<void> (0))
         "namespace includes neither ordinary nor tag")(static_cast<void> (0));
  assert(!(OldNS & ~(IDNS_Tag | IDNS_Ordinary | IDNS_Type |(static_cast<void> (0))
                     IDNS_TagFriend | IDNS_OrdinaryFriend |(static_cast<void> (0))
                     IDNS_LocalExtern | IDNS_NonMemberOperator)) &&(static_cast<void> (0))
         "namespace includes other than ordinary or tag")(static_cast<void> (0));

  Decl *Prev = getPreviousDecl();
  IdentifierNamespace &= ~(IDNS_Ordinary | IDNS_Tag | IDNS_Type);

  if (OldNS & (IDNS_Tag | IDNS_TagFriend)) {
    IdentifierNamespace |= IDNS_TagFriend;
    if (PerformFriendInjection ||
        (Prev && Prev->getIdentifierNamespace() & IDNS_Tag))
      IdentifierNamespace |= IDNS_Tag | IDNS_Type;
  }

  if (OldNS & (IDNS_Ordinary | IDNS_OrdinaryFriend |
               IDNS_LocalExtern | IDNS_NonMemberOperator)) {
    IdentifierNamespace |= IDNS_OrdinaryFriend;
    if (PerformFriendInjection ||
        (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary))
      IdentifierNamespace |= IDNS_Ordinary;
  }
}

enum FriendObjectKind {
  FOK_None,      ///< Not a friend object.
  FOK_Declared,  ///< A friend of a previously-declared entity.
  FOK_Undeclared ///< A friend of a previously-undeclared entity.
};

/// Determines whether this declaration is the object of a
/// friend declaration and, if so, what kind.
///
/// There is currently no direct way to find the associated FriendDecl.
FriendObjectKind getFriendObjectKind() const {
  unsigned mask =
      (IdentifierNamespace & (IDNS_TagFriend | IDNS_OrdinaryFriend));
  if (!mask) return FOK_None;
  return (IdentifierNamespace & (IDNS_Tag | IDNS_Ordinary) ? FOK_Declared
                                                           : FOK_Undeclared);
}

/// Specifies that this declaration is a C++ overloaded non-member.
void setNonMemberOperator() {
  assert(getKind() == Function || getKind() == FunctionTemplate)(static_cast<void> (0));
  assert((IdentifierNamespace & IDNS_Ordinary) &&(static_cast<void> (0))
         "visible non-member operators should be in ordinary namespace")(static_cast<void> (0));
  IdentifierNamespace |= IDNS_NonMemberOperator;
}

static bool classofKind(Kind K) { return true; }
static DeclContext *castToDeclContext(const Decl *);
static Decl *castFromDeclContext(const DeclContext *);

void print(raw_ostream &Out, unsigned Indentation = 0,
           bool PrintInstantiation = false) const;
void print(raw_ostream &Out, const PrintingPolicy &Policy,
           unsigned Indentation = 0, bool PrintInstantiation = false) const;
static void printGroup(Decl** Begin, unsigned NumDecls,
                       raw_ostream &Out, const PrintingPolicy &Policy,
                       unsigned Indentation = 0);

// Debuggers don't usually respect default arguments.
void dump() const;

// Same as dump(), but forces color printing.
void dumpColor() const;

void dump(raw_ostream &Out, bool Deserialize = false,
          ASTDumpOutputFormat OutputFormat = ADOF_Default) const;

/// \return Unique reproducible object identifier
int64_t getID() const;

/// Looks through the Decl's underlying type to extract a FunctionType
/// when possible. Will return null if the type underlying the Decl does not
/// have a FunctionType.
const FunctionType *getFunctionType(bool BlocksToo = true) const;

1188private:
void setAttrsImpl(const AttrVec& Attrs, ASTContext &Ctx);
void setDeclContextsImpl(DeclContext *SemaDC, DeclContext *LexicalDC,
                         ASTContext &Ctx);

1193protected:
ASTMutationListener *getASTMutationListener() const;
1195};

1197/// Determine whether two declarations declare the same entity.
1198inline bool declaresSameEntity(const Decl *D1, const Decl *D2) {
if (!D1 || !D2)
  return false;

if (D1 == D2)
  return true;

return D1->getCanonicalDecl() == D2->getCanonicalDecl();
1206}

1208/// PrettyStackTraceDecl - If a crash occurs, indicate that it happened when
1209/// doing something to a specific decl.
1210class PrettyStackTraceDecl : public llvm::PrettyStackTraceEntry {
const Decl *TheDecl;
SourceLocation Loc;
SourceManager &SM;
const char *Message;

1216public:
PrettyStackTraceDecl(const Decl *theDecl, SourceLocation L,
                     SourceManager &sm, const char *Msg)
    : TheDecl(theDecl), Loc(L), SM(sm), Message(Msg) {}

void print(raw_ostream &OS) const override;
1222};
1223} // namespace clang

1225// Required to determine the layout of the PointerUnion<NamedDecl*> before
1226// seeing the NamedDecl definition being first used in DeclListNode::operator*.
1227namespace llvm {
template <> struct PointerLikeTypeTraits<::clang::NamedDecl *> {
  static inline void *getAsVoidPointer(::clang::NamedDecl *P) { return P; }
  static inline ::clang::NamedDecl *getFromVoidPointer(void *P) {
    return static_cast<::clang::NamedDecl *>(P);
  }
  static constexpr int NumLowBitsAvailable = 3;
};
1235}

1237namespace clang {
1238/// A list storing NamedDecls in the lookup tables.
1239class DeclListNode {
friend class ASTContext; // allocate, deallocate nodes.
friend class StoredDeclsList;
1242public:
using Decls = llvm::PointerUnion<NamedDecl*, DeclListNode*>;
class iterator {
  friend class DeclContextLookupResult;
  friend class StoredDeclsList;

  Decls Ptr;
  iterator(Decls Node) : Ptr(Node) { }
public:
  using difference_type = ptrdiff_t;
  using value_type = NamedDecl*;
  using pointer = void;
  using reference = value_type;
  using iterator_category = std::forward_iterator_tag;

  iterator() = default;

  reference operator*() const {
    assert(Ptr && "dereferencing end() iterator")(static_cast<void> (0));
    if (DeclListNode *CurNode = Ptr.dyn_cast<DeclListNode*>())
      return CurNode->D;
    return Ptr.get<NamedDecl*>();
  }
  void operator->() const { } // Unsupported.
  bool operator==(const iterator &X) const { return Ptr == X.Ptr; }
  bool operator!=(const iterator &X) const { return Ptr != X.Ptr; }
  inline iterator &operator++() { // ++It
    assert(!Ptr.isNull() && "Advancing empty iterator")(static_cast<void> (0));

    if (DeclListNode *CurNode = Ptr.dyn_cast<DeclListNode*>())
      Ptr = CurNode->Rest;
    else
      Ptr = nullptr;
    return *this;
  }
  iterator operator++(int) { // It++
    iterator temp = *this;
    ++(*this);
    return temp;
  }
  // Enables the pattern for (iterator I =..., E = I.end(); I != E; ++I)
  iterator end() { return iterator(); }
};
1285private:
NamedDecl *D = nullptr;
Decls Rest = nullptr;
DeclListNode(NamedDecl *ND) : D(ND) {}
1289};

1291/// The results of name lookup within a DeclContext.
1292class DeclContextLookupResult {
using Decls = DeclListNode::Decls;

/// When in collection form, this is what the Data pointer points to.
Decls Result;

1298public:
DeclContextLookupResult() = default;
DeclContextLookupResult(Decls Result) : Result(Result) {}

using iterator = DeclListNode::iterator;
using const_iterator = iterator;
using reference = iterator::reference;

iterator begin() { return iterator(Result); }
iterator end() { return iterator(); }
const_iterator begin() const {
  return const_cast<DeclContextLookupResult*>(this)->begin();
}
const_iterator end() const { return iterator(); }

bool empty() const { return Result.isNull();  }
bool isSingleResult() const { return Result.dyn_cast<NamedDecl*>(); }
reference front() const { return *begin(); }

// Find the first declaration of the given type in the list. Note that this
// is not in general the earliest-declared declaration, and should only be
// used when it's not possible for there to be more than one match or where
// it doesn't matter which one is found.
template<class T> T *find_first() const {
  for (auto *D : *this)
    if (T *Decl = dyn_cast<T>(D))
      return Decl;

  return nullptr;
}
1328};

1330/// DeclContext - This is used only as base class of specific decl types that
1331/// can act as declaration contexts. These decls are (only the top classes
1332/// that directly derive from DeclContext are mentioned, not their subclasses):
1333///
1334///   TranslationUnitDecl
1335///   ExternCContext
1336///   NamespaceDecl
1337///   TagDecl
1338///   OMPDeclareReductionDecl
1339///   OMPDeclareMapperDecl
1340///   FunctionDecl
1341///   ObjCMethodDecl
1342///   ObjCContainerDecl
1343///   LinkageSpecDecl
1344///   ExportDecl
1345///   BlockDecl
1346///   CapturedDecl
1347class DeclContext {
/// For makeDeclVisibleInContextImpl
friend class ASTDeclReader;
/// For reconcileExternalVisibleStorage, CreateStoredDeclsMap,
/// hasNeedToReconcileExternalVisibleStorage
friend class ExternalASTSource;
/// For CreateStoredDeclsMap
friend class DependentDiagnostic;
/// For hasNeedToReconcileExternalVisibleStorage,
/// hasLazyLocalLexicalLookups, hasLazyExternalLexicalLookups
friend class ASTWriter;

// We use uint64_t in the bit-fields below since some bit-fields
// cross the unsigned boundary and this breaks the packing.

/// Stores the bits used by DeclContext.
/// If modified NumDeclContextBit, the ctor of DeclContext and the accessor
/// methods in DeclContext should be updated appropriately.
class DeclContextBitfields {
  friend class DeclContext;
  /// DeclKind - This indicates which class this is.
  uint64_t DeclKind : 7;

  /// Whether this declaration context also has some external
  /// storage that contains additional declarations that are lexically
  /// part of this context.
  mutable uint64_t ExternalLexicalStorage : 1;

  /// Whether this declaration context also has some external
  /// storage that contains additional declarations that are visible
  /// in this context.
  mutable uint64_t ExternalVisibleStorage : 1;

  /// Whether this declaration context has had externally visible
  /// storage added since the last lookup. In this case, \c LookupPtr's
  /// invariant may not hold and needs to be fixed before we perform
  /// another lookup.
  mutable uint64_t NeedToReconcileExternalVisibleStorage : 1;

  /// If \c true, this context may have local lexical declarations
  /// that are missing from the lookup table.
  mutable uint64_t HasLazyLocalLexicalLookups : 1;

  /// If \c true, the external source may have lexical declarations
  /// that are missing from the lookup table.
  mutable uint64_t HasLazyExternalLexicalLookups : 1;

  /// If \c true, lookups should only return identifier from
  /// DeclContext scope (for example TranslationUnit). Used in
  /// LookupQualifiedName()
  mutable uint64_t UseQualifiedLookup : 1;
};

/// Number of bits in DeclContextBitfields.
enum { NumDeclContextBits = 13 };

/// Stores the bits used by TagDecl.
/// If modified NumTagDeclBits and the accessor
/// methods in TagDecl should be updated appropriately.
class TagDeclBitfields {
  friend class TagDecl;
  /// For the bits in DeclContextBitfields
  uint64_t : NumDeclContextBits;

  /// The TagKind enum.
  uint64_t TagDeclKind : 3;

  /// True if this is a definition ("struct foo {};"), false if it is a
  /// declaration ("struct foo;").  It is not considered a definition
  /// until the definition has been fully processed.
  uint64_t IsCompleteDefinition : 1;

  /// True if this is currently being defined.
  uint64_t IsBeingDefined : 1;

  /// True if this tag declaration is "embedded" (i.e., defined or declared
  /// for the very first time) in the syntax of a declarator.
  uint64_t IsEmbeddedInDeclarator : 1;

  /// True if this tag is free standing, e.g. "struct foo;".
  uint64_t IsFreeStanding : 1;

  /// Indicates whether it is possible for declarations of this kind
  /// to have an out-of-date definition.
  ///
  /// This option is only enabled when modules are enabled.
  uint64_t MayHaveOutOfDateDef : 1;

  /// Has the full definition of this type been required by a use somewhere in
  /// the TU.
  uint64_t IsCompleteDefinitionRequired : 1;
};

/// Number of non-inherited bits in TagDeclBitfields.
enum { NumTagDeclBits = 9 };

/// Stores the bits used by EnumDecl.
/// If modified NumEnumDeclBit and the accessor
/// methods in EnumDecl should be updated appropriately.
class EnumDeclBitfields {
  friend class EnumDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;
  /// For the bits in TagDeclBitfields.
  uint64_t : NumTagDeclBits;

  /// Width in bits required to store all the non-negative
  /// enumerators of this enum.
  uint64_t NumPositiveBits : 8;

  /// Width in bits required to store all the negative
  /// enumerators of this enum.
  uint64_t NumNegativeBits : 8;

  /// True if this tag declaration is a scoped enumeration. Only
  /// possible in C++11 mode.
  uint64_t IsScoped : 1;

  /// If this tag declaration is a scoped enum,
  /// then this is true if the scoped enum was declared using the class
  /// tag, false if it was declared with the struct tag. No meaning is
  /// associated if this tag declaration is not a scoped enum.
  uint64_t IsScopedUsingClassTag : 1;

  /// True if this is an enumeration with fixed underlying type. Only
  /// possible in C++11, Microsoft extensions, or Objective C mode.
  uint64_t IsFixed : 1;

  /// True if a valid hash is stored in ODRHash.
  uint64_t HasODRHash : 1;
};

/// Number of non-inherited bits in EnumDeclBitfields.
enum { NumEnumDeclBits = 20 };

/// Stores the bits used by RecordDecl.
/// If modified NumRecordDeclBits and the accessor
/// methods in RecordDecl should be updated appropriately.
class RecordDeclBitfields {
  friend class RecordDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;
  /// For the bits in TagDeclBitfields.
  uint64_t : NumTagDeclBits;

  /// This is true if this struct ends with a flexible
  /// array member (e.g. int X[]) or if this union contains a struct that does.
  /// If so, this cannot be contained in arrays or other structs as a member.
  uint64_t HasFlexibleArrayMember : 1;

  /// Whether this is the type of an anonymous struct or union.
  uint64_t AnonymousStructOrUnion : 1;

  /// This is true if this struct has at least one member
  /// containing an Objective-C object pointer type.
  uint64_t HasObjectMember : 1;

  /// This is true if struct has at least one member of
  /// 'volatile' type.
  uint64_t HasVolatileMember : 1;

  /// Whether the field declarations of this record have been loaded
  /// from external storage. To avoid unnecessary deserialization of
  /// methods/nested types we allow deserialization of just the fields
  /// when needed.
  mutable uint64_t LoadedFieldsFromExternalStorage : 1;

  /// Basic properties of non-trivial C structs.
  uint64_t NonTrivialToPrimitiveDefaultInitialize : 1;
  uint64_t NonTrivialToPrimitiveCopy : 1;
  uint64_t NonTrivialToPrimitiveDestroy : 1;

  /// The following bits indicate whether this is or contains a C union that
  /// is non-trivial to default-initialize, destruct, or copy. These bits
  /// imply the associated basic non-triviality predicates declared above.
  uint64_t HasNonTrivialToPrimitiveDefaultInitializeCUnion : 1;
  uint64_t HasNonTrivialToPrimitiveDestructCUnion : 1;
  uint64_t HasNonTrivialToPrimitiveCopyCUnion : 1;

  /// Indicates whether this struct is destroyed in the callee.
  uint64_t ParamDestroyedInCallee : 1;

  /// Represents the way this type is passed to a function.
  uint64_t ArgPassingRestrictions : 2;
};

/// Number of non-inherited bits in RecordDeclBitfields.
enum { NumRecordDeclBits = 14 };

/// Stores the bits used by OMPDeclareReductionDecl.
/// If modified NumOMPDeclareReductionDeclBits and the accessor
/// methods in OMPDeclareReductionDecl should be updated appropriately.
class OMPDeclareReductionDeclBitfields {
  friend class OMPDeclareReductionDecl;
  /// For the bits in DeclContextBitfields
  uint64_t : NumDeclContextBits;

  /// Kind of initializer,
  /// function call or omp_priv<init_expr> initializtion.
  uint64_t InitializerKind : 2;
};

/// Number of non-inherited bits in OMPDeclareReductionDeclBitfields.
enum { NumOMPDeclareReductionDeclBits = 2 };

/// Stores the bits used by FunctionDecl.
/// If modified NumFunctionDeclBits and the accessor
/// methods in FunctionDecl and CXXDeductionGuideDecl
/// (for IsCopyDeductionCandidate) should be updated appropriately.
class FunctionDeclBitfields {
  friend class FunctionDecl;
  /// For IsCopyDeductionCandidate
  friend class CXXDeductionGuideDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  uint64_t SClass : 3;
  uint64_t IsInline : 1;
  uint64_t IsInlineSpecified : 1;

  uint64_t IsVirtualAsWritten : 1;
  uint64_t IsPure : 1;
  uint64_t HasInheritedPrototype : 1;
  uint64_t HasWrittenPrototype : 1;
  uint64_t IsDeleted : 1;
  /// Used by CXXMethodDecl
  uint64_t IsTrivial : 1;

  /// This flag indicates whether this function is trivial for the purpose of
  /// calls. This is meaningful only when this function is a copy/move
  /// constructor or a destructor.
  uint64_t IsTrivialForCall : 1;

  uint64_t IsDefaulted : 1;
  uint64_t IsExplicitlyDefaulted : 1;
  uint64_t HasDefaultedFunctionInfo : 1;
  uint64_t HasImplicitReturnZero : 1;
  uint64_t IsLateTemplateParsed : 1;

  /// Kind of contexpr specifier as defined by ConstexprSpecKind.
  uint64_t ConstexprKind : 2;
  uint64_t InstantiationIsPending : 1;

  /// Indicates if the function uses __try.
  uint64_t UsesSEHTry : 1;

  /// Indicates if the function was a definition
  /// but its body was skipped.
  uint64_t HasSkippedBody : 1;

  /// Indicates if the function declaration will
  /// have a body, once we're done parsing it.
  uint64_t WillHaveBody : 1;

  /// Indicates that this function is a multiversioned
  /// function using attribute 'target'.
  uint64_t IsMultiVersion : 1;

  /// [C++17] Only used by CXXDeductionGuideDecl. Indicates that
  /// the Deduction Guide is the implicitly generated 'copy
  /// deduction candidate' (is used during overload resolution).
  uint64_t IsCopyDeductionCandidate : 1;

  /// Store the ODRHash after first calculation.
  uint64_t HasODRHash : 1;

  /// Indicates if the function uses Floating Point Constrained Intrinsics
  uint64_t UsesFPIntrin : 1;
};

/// Number of non-inherited bits in FunctionDeclBitfields.
enum { NumFunctionDeclBits = 27 };

/// Stores the bits used by CXXConstructorDecl. If modified
/// NumCXXConstructorDeclBits and the accessor
/// methods in CXXConstructorDecl should be updated appropriately.
class CXXConstructorDeclBitfields {
  friend class CXXConstructorDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;
  /// For the bits in FunctionDeclBitfields.
  uint64_t : NumFunctionDeclBits;

  /// 24 bits to fit in the remaining available space.
  /// Note that this makes CXXConstructorDeclBitfields take
  /// exactly 64 bits and thus the width of NumCtorInitializers
  /// will need to be shrunk if some bit is added to NumDeclContextBitfields,
  /// NumFunctionDeclBitfields or CXXConstructorDeclBitfields.
  uint64_t NumCtorInitializers : 21;
  uint64_t IsInheritingConstructor : 1;

  /// Whether this constructor has a trail-allocated explicit specifier.
  uint64_t HasTrailingExplicitSpecifier : 1;
  /// If this constructor does't have a trail-allocated explicit specifier.
  /// Whether this constructor is explicit specified.
  uint64_t IsSimpleExplicit : 1;
};

/// Number of non-inherited bits in CXXConstructorDeclBitfields.
enum {
  NumCXXConstructorDeclBits = 64 - NumDeclContextBits - NumFunctionDeclBits
};

/// Stores the bits used by ObjCMethodDecl.
/// If modified NumObjCMethodDeclBits and the accessor
/// methods in ObjCMethodDecl should be updated appropriately.
class ObjCMethodDeclBitfields {
  friend class ObjCMethodDecl;

  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  /// The conventional meaning of this method; an ObjCMethodFamily.
  /// This is not serialized; instead, it is computed on demand and
  /// cached.
  mutable uint64_t Family : ObjCMethodFamilyBitWidth;

  /// instance (true) or class (false) method.
  uint64_t IsInstance : 1;
  uint64_t IsVariadic : 1;

  /// True if this method is the getter or setter for an explicit property.
  uint64_t IsPropertyAccessor : 1;

  /// True if this method is a synthesized property accessor stub.
  uint64_t IsSynthesizedAccessorStub : 1;

  /// Method has a definition.
  uint64_t IsDefined : 1;

  /// Method redeclaration in the same interface.
  uint64_t IsRedeclaration : 1;

  /// Is redeclared in the same interface.
  mutable uint64_t HasRedeclaration : 1;

  /// \@required/\@optional
  uint64_t DeclImplementation : 2;

  /// in, inout, etc.
  uint64_t objcDeclQualifier : 7;

  /// Indicates whether this method has a related result type.
  uint64_t RelatedResultType : 1;

  /// Whether the locations of the selector identifiers are in a
  /// "standard" position, a enum SelectorLocationsKind.
  uint64_t SelLocsKind : 2;

  /// Whether this method overrides any other in the class hierarchy.
  ///
  /// A method is said to override any method in the class's
  /// base classes, its protocols, or its categories' protocols, that has
  /// the same selector and is of the same kind (class or instance).
  /// A method in an implementation is not considered as overriding the same
  /// method in the interface or its categories.
  uint64_t IsOverriding : 1;

  /// Indicates if the method was a definition but its body was skipped.
  uint64_t HasSkippedBody : 1;
};

/// Number of non-inherited bits in ObjCMethodDeclBitfields.
enum { NumObjCMethodDeclBits = 24 };

/// Stores the bits used by ObjCContainerDecl.
/// If modified NumObjCContainerDeclBits and the accessor
/// methods in ObjCContainerDecl should be updated appropriately.
class ObjCContainerDeclBitfields {
  friend class ObjCContainerDecl;
  /// For the bits in DeclContextBitfields
  uint32_t : NumDeclContextBits;

  // Not a bitfield but this saves space.
  // Note that ObjCContainerDeclBitfields is full.
  SourceLocation AtStart;
};

/// Number of non-inherited bits in ObjCContainerDeclBitfields.
/// Note that here we rely on the fact that SourceLocation is 32 bits
/// wide. We check this with the static_assert in the ctor of DeclContext.
enum { NumObjCContainerDeclBits = 64 - NumDeclContextBits };

/// Stores the bits used by LinkageSpecDecl.
/// If modified NumLinkageSpecDeclBits and the accessor
/// methods in LinkageSpecDecl should be updated appropriately.
class LinkageSpecDeclBitfields {
  friend class LinkageSpecDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  /// The language for this linkage specification with values
  /// in the enum LinkageSpecDecl::LanguageIDs.
  uint64_t Language : 3;

  /// True if this linkage spec has braces.
  /// This is needed so that hasBraces() returns the correct result while the
  /// linkage spec body is being parsed.  Once RBraceLoc has been set this is
  /// not used, so it doesn't need to be serialized.
  uint64_t HasBraces : 1;
};

/// Number of non-inherited bits in LinkageSpecDeclBitfields.
enum { NumLinkageSpecDeclBits = 4 };

/// Stores the bits used by BlockDecl.
/// If modified NumBlockDeclBits and the accessor
/// methods in BlockDecl should be updated appropriately.
class BlockDeclBitfields {
  friend class BlockDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  uint64_t IsVariadic : 1;
  uint64_t CapturesCXXThis : 1;
  uint64_t BlockMissingReturnType : 1;
  uint64_t IsConversionFromLambda : 1;

  /// A bit that indicates this block is passed directly to a function as a
  /// non-escaping parameter.
  uint64_t DoesNotEscape : 1;

  /// A bit that indicates whether it's possible to avoid coying this block to
  /// the heap when it initializes or is assigned to a local variable with
  /// automatic storage.
  uint64_t CanAvoidCopyToHeap : 1;
};

/// Number of non-inherited bits in BlockDeclBitfields.
enum { NumBlockDeclBits = 5 };

/// Pointer to the data structure used to lookup declarations
/// within this context (or a DependentStoredDeclsMap if this is a
/// dependent context). We maintain the invariant that, if the map
/// contains an entry for a DeclarationName (and we haven't lazily
/// omitted anything), then it contains all relevant entries for that
/// name (modulo the hasExternalDecls() flag).
mutable StoredDeclsMap *LookupPtr = nullptr;

1786protected:
/// This anonymous union stores the bits belonging to DeclContext and classes
/// deriving from it. The goal is to use otherwise wasted
/// space in DeclContext to store data belonging to derived classes.
/// The space saved is especially significient when pointers are aligned
/// to 8 bytes. In this case due to alignment requirements we have a
/// little less than 8 bytes free in DeclContext which we can use.
/// We check that none of the classes in this union is larger than
/// 8 bytes with static_asserts in the ctor of DeclContext.
union {
  DeclContextBitfields DeclContextBits;
  TagDeclBitfields TagDeclBits;
  EnumDeclBitfields EnumDeclBits;
  RecordDeclBitfields RecordDeclBits;
  OMPDeclareReductionDeclBitfields OMPDeclareReductionDeclBits;
  FunctionDeclBitfields FunctionDeclBits;
  CXXConstructorDeclBitfields CXXConstructorDeclBits;
  ObjCMethodDeclBitfields ObjCMethodDeclBits;
  ObjCContainerDeclBitfields ObjCContainerDeclBits;
  LinkageSpecDeclBitfields LinkageSpecDeclBits;
  BlockDeclBitfields BlockDeclBits;

  static_assert(sizeof(DeclContextBitfields) <= 8,
                "DeclContextBitfields is larger than 8 bytes!");
  static_assert(sizeof(TagDeclBitfields) <= 8,
                "TagDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(EnumDeclBitfields) <= 8,
                "EnumDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(RecordDeclBitfields) <= 8,
                "RecordDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(OMPDeclareReductionDeclBitfields) <= 8,
                "OMPDeclareReductionDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(FunctionDeclBitfields) <= 8,
                "FunctionDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(CXXConstructorDeclBitfields) <= 8,
                "CXXConstructorDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(ObjCMethodDeclBitfields) <= 8,
                "ObjCMethodDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(ObjCContainerDeclBitfields) <= 8,
                "ObjCContainerDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(LinkageSpecDeclBitfields) <= 8,
                "LinkageSpecDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(BlockDeclBitfields) <= 8,
                "BlockDeclBitfields is larger than 8 bytes!");
};

/// FirstDecl - The first declaration stored within this declaration
/// context.
mutable Decl *FirstDecl = nullptr;

/// LastDecl - The last declaration stored within this declaration
/// context. FIXME: We could probably cache this value somewhere
/// outside of the DeclContext, to reduce the size of DeclContext by
/// another pointer.
mutable Decl *LastDecl = nullptr;

/// Build up a chain of declarations.
///
/// \returns the first/last pair of declarations.
static std::pair<Decl *, Decl *>
BuildDeclChain(ArrayRef<Decl*> Decls, bool FieldsAlreadyLoaded);

DeclContext(Decl::Kind K);

1850public:
~DeclContext();

Decl::Kind getDeclKind() const {
  return static_cast<Decl::Kind>(DeclContextBits.DeclKind);
}

const char *getDeclKindName() const;

/// getParent - Returns the containing DeclContext.
DeclContext *getParent() {
  return cast<Decl>(this)->getDeclContext();
}
const DeclContext *getParent() const {
  return const_cast<DeclContext*>(this)->getParent();
}

/// getLexicalParent - Returns the containing lexical DeclContext. May be
/// different from getParent, e.g.:
///
///   namespace A {
///      struct S;
///   }
///   struct A::S {}; // getParent() == namespace 'A'
///                   // getLexicalParent() == translation unit
///
DeclContext *getLexicalParent() {
  return cast<Decl>(this)->getLexicalDeclContext();
}
const DeclContext *getLexicalParent() const {
  return const_cast<DeclContext*>(this)->getLexicalParent();
}

DeclContext *getLookupParent();

const DeclContext *getLookupParent() const {
  return const_cast<DeclContext*>(this)->getLookupParent();
}

ASTContext &getParentASTContext() const {
  return cast<Decl>(this)->getASTContext();
}

bool isClosure() const { return getDeclKind() == Decl::Block; }

/// Return this DeclContext if it is a BlockDecl. Otherwise, return the
/// innermost enclosing BlockDecl or null if there are no enclosing blocks.
const BlockDecl *getInnermostBlockDecl() const;

bool isObjCContainer() const {
  switch (getDeclKind()) {
  case Decl::ObjCCategory:
  case Decl::ObjCCategoryImpl:
  case Decl::ObjCImplementation:
  case Decl::ObjCInterface:
  case Decl::ObjCProtocol:
    return true;
  default:
    return false;
  }
}

bool isFunctionOrMethod() const {
  switch (getDeclKind()) {
  case Decl::Block:
  case Decl::Captured:
  case Decl::ObjCMethod:
    return true;
  default:
    return getDeclKind() >= Decl::firstFunction &&
           getDeclKind() <= Decl::lastFunction;
  }
}

/// Test whether the context supports looking up names.
bool isLookupContext() const {
  return !isFunctionOrMethod() && getDeclKind() != Decl::LinkageSpec &&
         getDeclKind() != Decl::Export;
}

bool isFileContext() const {
  return getDeclKind() == Decl::TranslationUnit ||
         getDeclKind() == Decl::Namespace;
}

bool isTranslationUnit() const {
  return getDeclKind() == Decl::TranslationUnit;
8
←
Assuming the condition is false→
9
←
Returning zero, which participates in a condition later→
}

bool isRecord() const {
  return getDeclKind() >= Decl::firstRecord &&
         getDeclKind() <= Decl::lastRecord;
}

bool isNamespace() const { return getDeclKind() == Decl::Namespace; }

bool isStdNamespace() const;

bool isInlineNamespace() const;

/// Determines whether this context is dependent on a
/// template parameter.
bool isDependentContext() const;

/// isTransparentContext - Determines whether this context is a
/// "transparent" context, meaning that the members declared in this
/// context are semantically declared in the nearest enclosing
/// non-transparent (opaque) context but are lexically declared in
/// this context. For example, consider the enumerators of an
/// enumeration type:
/// @code
/// enum E {
///   Val1
/// };
/// @endcode
/// Here, E is a transparent context, so its enumerator (Val1) will
/// appear (semantically) that it is in the same context of E.
/// Examples of transparent contexts include: enumerations (except for
/// C++0x scoped enums), and C++ linkage specifications.
bool isTransparentContext() const;

/// Determines whether this context or some of its ancestors is a
/// linkage specification context that specifies C linkage.
bool isExternCContext() const;

/// Retrieve the nearest enclosing C linkage specification context.
const LinkageSpecDecl *getExternCContext() const;

/// Determines whether this context or some of its ancestors is a
/// linkage specification context that specifies C++ linkage.
bool isExternCXXContext() const;

/// Determine whether this declaration context is equivalent
/// to the declaration context DC.
bool Equals(const DeclContext *DC) const {
  return DC && this->getPrimaryContext() == DC->getPrimaryContext();
}

/// Determine whether this declaration context encloses the
/// declaration context DC.
bool Encloses(const DeclContext *DC) const;

/// Find the nearest non-closure ancestor of this context,
/// i.e. the innermost semantic parent of this context which is not
/// a closure.  A context may be its own non-closure ancestor.
Decl *getNonClosureAncestor();
const Decl *getNonClosureAncestor() const {
  return const_cast<DeclContext*>(this)->getNonClosureAncestor();
}

// Retrieve the nearest context that is not a transparent context.
DeclContext *getNonTransparentContext();
const DeclContext *getNonTransparentContext() const {
  return const_cast<DeclContext *>(this)->getNonTransparentContext();
}

/// getPrimaryContext - There may be many different
/// declarations of the same entity (including forward declarations
/// of classes, multiple definitions of namespaces, etc.), each with
/// a different set of declarations. This routine returns the
/// "primary" DeclContext structure, which will contain the
/// information needed to perform name lookup into this context.
DeclContext *getPrimaryContext();
const DeclContext *getPrimaryContext() const {
  return const_cast<DeclContext*>(this)->getPrimaryContext();
}

/// getRedeclContext - Retrieve the context in which an entity conflicts with
/// other entities of the same name, or where it is a redeclaration if the
/// two entities are compatible. This skips through transparent contexts.
DeclContext *getRedeclContext();
const DeclContext *getRedeclContext() const {
  return const_cast<DeclContext *>(this)->getRedeclContext();
}

/// Retrieve the nearest enclosing namespace context.
DeclContext *getEnclosingNamespaceContext();
const DeclContext *getEnclosingNamespaceContext() const {
  return const_cast<DeclContext *>(this)->getEnclosingNamespaceContext();
}

/// Retrieve the outermost lexically enclosing record context.
RecordDecl *getOuterLexicalRecordContext();
const RecordDecl *getOuterLexicalRecordContext() const {
  return const_cast<DeclContext *>(this)->getOuterLexicalRecordContext();
}

/// Test if this context is part of the enclosing namespace set of
/// the context NS, as defined in C++0x [namespace.def]p9. If either context
/// isn't a namespace, this is equivalent to Equals().
///
/// The enclosing namespace set of a namespace is the namespace and, if it is
/// inline, its enclosing namespace, recursively.
bool InEnclosingNamespaceSetOf(const DeclContext *NS) const;

/// Collects all of the declaration contexts that are semantically
/// connected to this declaration context.
///
/// For declaration contexts that have multiple semantically connected but
/// syntactically distinct contexts, such as C++ namespaces, this routine
/// retrieves the complete set of such declaration contexts in source order.
/// For example, given:
///
/// \code
/// namespace N {
///   int x;
/// }
/// namespace N {
///   int y;
/// }
/// \endcode
///
/// The \c Contexts parameter will contain both definitions of N.
///
/// \param Contexts Will be cleared and set to the set of declaration
/// contexts that are semanticaly connected to this declaration context,
/// in source order, including this context (which may be the only result,
/// for non-namespace contexts).
void collectAllContexts(SmallVectorImpl<DeclContext *> &Contexts);

/// decl_iterator - Iterates through the declarations stored
/// within this context.
class decl_iterator {
  /// Current - The current declaration.
  Decl *Current = nullptr;

public:
  using value_type = Decl *;
  using reference = const value_type &;
  using pointer = const value_type *;
  using iterator_category = std::forward_iterator_tag;
  using difference_type = std::ptrdiff_t;

  decl_iterator() = default;
  explicit decl_iterator(Decl *C) : Current(C) {}

  reference operator*() const { return Current; }

  // This doesn't meet the iterator requirements, but it's convenient
  value_type operator->() const { return Current; }

  decl_iterator& operator++() {
    Current = Current->getNextDeclInContext();
    return *this;
  }

  decl_iterator operator++(int) {
    decl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(decl_iterator x, decl_iterator y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(decl_iterator x, decl_iterator y) {
    return x.Current != y.Current;
  }
};

using decl_range = llvm::iterator_range<decl_iterator>;

/// decls_begin/decls_end - Iterate over the declarations stored in
/// this context.
decl_range decls() const { return decl_range(decls_begin(), decls_end()); }
decl_iterator decls_begin() const;
decl_iterator decls_end() const { return decl_iterator(); }
bool decls_empty() const;

/// noload_decls_begin/end - Iterate over the declarations stored in this
/// context that are currently loaded; don't attempt to retrieve anything
/// from an external source.
decl_range noload_decls() const {
  return decl_range(noload_decls_begin(), noload_decls_end());
}
decl_iterator noload_decls_begin() const { return decl_iterator(FirstDecl); }
decl_iterator noload_decls_end() const { return decl_iterator(); }

/// specific_decl_iterator - Iterates over a subrange of
/// declarations stored in a DeclContext, providing only those that
/// are of type SpecificDecl (or a class derived from it). This
/// iterator is used, for example, to provide iteration over just
/// the fields within a RecordDecl (with SpecificDecl = FieldDecl).
template<typename SpecificDecl>
class specific_decl_iterator {
  /// Current - The current, underlying declaration iterator, which
  /// will either be NULL or will point to a declaration of
  /// type SpecificDecl.
  DeclContext::decl_iterator Current;

  /// SkipToNextDecl - Advances the current position up to the next
  /// declaration of type SpecificDecl that also meets the criteria
  /// required by Acceptable.
  void SkipToNextDecl() {
    while (*Current && !isa<SpecificDecl>(*Current))
      ++Current;
  }

public:
  using value_type = SpecificDecl *;
  // TODO: Add reference and pointer types (with some appropriate proxy type)
  // if we ever have a need for them.
  using reference = void;
  using pointer = void;
  using difference_type =
      std::iterator_traits<DeclContext::decl_iterator>::difference_type;
  using iterator_category = std::forward_iterator_tag;

  specific_decl_iterator() = default;

  /// specific_decl_iterator - Construct a new iterator over a
  /// subset of the declarations the range [C,
  /// end-of-declarations). If A is non-NULL, it is a pointer to a
  /// member function of SpecificDecl that should return true for
  /// all of the SpecificDecl instances that will be in the subset
  /// of iterators. For example, if you want Objective-C instance
  /// methods, SpecificDecl will be ObjCMethodDecl and A will be
  /// &ObjCMethodDecl::isInstanceMethod.
  explicit specific_decl_iterator(DeclContext::decl_iterator C) : Current(C) {
    SkipToNextDecl();
  }

  value_type operator*() const { return cast<SpecificDecl>(*Current); }

  // This doesn't meet the iterator requirements, but it's convenient
  value_type operator->() const { return **this; }

  specific_decl_iterator& operator++() {
    ++Current;
    SkipToNextDecl();
    return *this;
  }

  specific_decl_iterator operator++(int) {
    specific_decl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(const specific_decl_iterator& x,
                         const specific_decl_iterator& y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(const specific_decl_iterator& x,
                         const specific_decl_iterator& y) {
    return x.Current != y.Current;
  }
};

/// Iterates over a filtered subrange of declarations stored
/// in a DeclContext.
///
/// This iterator visits only those declarations that are of type
/// SpecificDecl (or a class derived from it) and that meet some
/// additional run-time criteria. This iterator is used, for
/// example, to provide access to the instance methods within an
/// Objective-C interface (with SpecificDecl = ObjCMethodDecl and
/// Acceptable = ObjCMethodDecl::isInstanceMethod).
template<typename SpecificDecl, bool (SpecificDecl::*Acceptable)() const>
class filtered_decl_iterator {
  /// Current - The current, underlying declaration iterator, which
  /// will either be NULL or will point to a declaration of
  /// type SpecificDecl.
  DeclContext::decl_iterator Current;

  /// SkipToNextDecl - Advances the current position up to the next
  /// declaration of type SpecificDecl that also meets the criteria
  /// required by Acceptable.
  void SkipToNextDecl() {
    while (*Current &&
           (!isa<SpecificDecl>(*Current) ||
            (Acceptable && !(cast<SpecificDecl>(*Current)->*Acceptable)())))
      ++Current;
  }

public:
  using value_type = SpecificDecl *;
  // TODO: Add reference and pointer types (with some appropriate proxy type)
  // if we ever have a need for them.
  using reference = void;
  using pointer = void;
  using difference_type =
      std::iterator_traits<DeclContext::decl_iterator>::difference_type;
  using iterator_category = std::forward_iterator_tag;

  filtered_decl_iterator() = default;

  /// filtered_decl_iterator - Construct a new iterator over a
  /// subset of the declarations the range [C,
  /// end-of-declarations). If A is non-NULL, it is a pointer to a
  /// member function of SpecificDecl that should return true for
  /// all of the SpecificDecl instances that will be in the subset
  /// of iterators. For example, if you want Objective-C instance
  /// methods, SpecificDecl will be ObjCMethodDecl and A will be
  /// &ObjCMethodDecl::isInstanceMethod.
  explicit filtered_decl_iterator(DeclContext::decl_iterator C) : Current(C) {
    SkipToNextDecl();
  }

  value_type operator*() const { return cast<SpecificDecl>(*Current); }
  value_type operator->() const { return cast<SpecificDecl>(*Current); }

  filtered_decl_iterator& operator++() {
    ++Current;
    SkipToNextDecl();
    return *this;
  }

  filtered_decl_iterator operator++(int) {
    filtered_decl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(const filtered_decl_iterator& x,
                         const filtered_decl_iterator& y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(const filtered_decl_iterator& x,
                         const filtered_decl_iterator& y) {
    return x.Current != y.Current;
  }
};

/// Add the declaration D into this context.
///
/// This routine should be invoked when the declaration D has first
/// been declared, to place D into the context where it was
/// (lexically) defined. Every declaration must be added to one
/// (and only one!) context, where it can be visited via
/// [decls_begin(), decls_end()). Once a declaration has been added
/// to its lexical context, the corresponding DeclContext owns the
/// declaration.
///
/// If D is also a NamedDecl, it will be made visible within its
/// semantic context via makeDeclVisibleInContext.
void addDecl(Decl *D);

/// Add the declaration D into this context, but suppress
/// searches for external declarations with the same name.
///
/// Although analogous in function to addDecl, this removes an
/// important check.  This is only useful if the Decl is being
/// added in response to an external search; in all other cases,
/// addDecl() is the right function to use.
/// See the ASTImporter for use cases.
void addDeclInternal(Decl *D);

/// Add the declaration D to this context without modifying
/// any lookup tables.
///
/// This is useful for some operations in dependent contexts where
/// the semantic context might not be dependent;  this basically
/// only happens with friends.
void addHiddenDecl(Decl *D);

/// Removes a declaration from this context.
void removeDecl(Decl *D);

/// Checks whether a declaration is in this context.
bool containsDecl(Decl *D) const;

/// Checks whether a declaration is in this context.
/// This also loads the Decls from the external source before the check.
bool containsDeclAndLoad(Decl *D) const;

using lookup_result = DeclContextLookupResult;
using lookup_iterator = lookup_result::iterator;

/// lookup - Find the declarations (if any) with the given Name in
/// this context. Returns a range of iterators that contains all of
/// the declarations with this name, with object, function, member,
/// and enumerator names preceding any tag name. Note that this
/// routine will not look into parent contexts.
lookup_result lookup(DeclarationName Name) const;

/// Find the declarations with the given name that are visible
/// within this context; don't attempt to retrieve anything from an
/// external source.
lookup_result noload_lookup(DeclarationName Name);

/// A simplistic name lookup mechanism that performs name lookup
/// into this declaration context without consulting the external source.
///
/// This function should almost never be used, because it subverts the
/// usual relationship between a DeclContext and the external source.
/// See the ASTImporter for the (few, but important) use cases.
///
/// FIXME: This is very inefficient; replace uses of it with uses of
/// noload_lookup.
void localUncachedLookup(DeclarationName Name,
                         SmallVectorImpl<NamedDecl *> &Results);

/// Makes a declaration visible within this context.
///
/// This routine makes the declaration D visible to name lookup
/// within this context and, if this is a transparent context,
/// within its parent contexts up to the first enclosing
/// non-transparent context. Making a declaration visible within a
/// context does not transfer ownership of a declaration, and a
/// declaration can be visible in many contexts that aren't its
/// lexical context.
///
/// If D is a redeclaration of an existing declaration that is
/// visible from this context, as determined by
/// NamedDecl::declarationReplaces, the previous declaration will be
/// replaced with D.
void makeDeclVisibleInContext(NamedDecl *D);

/// all_lookups_iterator - An iterator that provides a view over the results
/// of looking up every possible name.
class all_lookups_iterator;

using lookups_range = llvm::iterator_range<all_lookups_iterator>;

lookups_range lookups() const;
// Like lookups(), but avoids loading external declarations.
// If PreserveInternalState, avoids building lookup data structures too.
lookups_range noload_lookups(bool PreserveInternalState) const;

/// Iterators over all possible lookups within this context.
all_lookups_iterator lookups_begin() const;
all_lookups_iterator lookups_end() const;

/// Iterators over all possible lookups within this context that are
/// currently loaded; don't attempt to retrieve anything from an external
/// source.
all_lookups_iterator noload_lookups_begin() const;
all_lookups_iterator noload_lookups_end() const;

struct udir_iterator;

using udir_iterator_base =
    llvm::iterator_adaptor_base<udir_iterator, lookup_iterator,
                                typename lookup_iterator::iterator_category,
                                UsingDirectiveDecl *>;

struct udir_iterator : udir_iterator_base {
  udir_iterator(lookup_iterator I) : udir_iterator_base(I) {}

  UsingDirectiveDecl *operator*() const;
};

using udir_range = llvm::iterator_range<udir_iterator>;

udir_range using_directives() const;

// These are all defined in DependentDiagnostic.h.
class ddiag_iterator;

using ddiag_range = llvm::iterator_range<DeclContext::ddiag_iterator>;

inline ddiag_range ddiags() const;

// Low-level accessors

/// Mark that there are external lexical declarations that we need
/// to include in our lookup table (and that are not available as external
/// visible lookups). These extra lookup results will be found by walking
/// the lexical declarations of this context. This should be used only if
/// setHasExternalLexicalStorage() has been called on any decl context for
/// which this is the primary context.
void setMustBuildLookupTable() {
  assert(this == getPrimaryContext() &&(static_cast<void> (0))
         "should only be called on primary context")(static_cast<void> (0));
  DeclContextBits.HasLazyExternalLexicalLookups = true;
}

/// Retrieve the internal representation of the lookup structure.
/// This may omit some names if we are lazily building the structure.
StoredDeclsMap *getLookupPtr() const { return LookupPtr; }

/// Ensure the lookup structure is fully-built and return it.
StoredDeclsMap *buildLookup();

/// Whether this DeclContext has external storage containing
/// additional declarations that are lexically in this context.
bool hasExternalLexicalStorage() const {
  return DeclContextBits.ExternalLexicalStorage;
}

/// State whether this DeclContext has external storage for
/// declarations lexically in this context.
void setHasExternalLexicalStorage(bool ES = true) const {
  DeclContextBits.ExternalLexicalStorage = ES;
}

/// Whether this DeclContext has external storage containing
/// additional declarations that are visible in this context.
bool hasExternalVisibleStorage() const {
  return DeclContextBits.ExternalVisibleStorage;
}

/// State whether this DeclContext has external storage for
/// declarations visible in this context.
void setHasExternalVisibleStorage(bool ES = true) const {
  DeclContextBits.ExternalVisibleStorage = ES;
  if (ES && LookupPtr)
    DeclContextBits.NeedToReconcileExternalVisibleStorage = true;
}

/// Determine whether the given declaration is stored in the list of
/// declarations lexically within this context.
bool isDeclInLexicalTraversal(const Decl *D) const {
  return D && (D->NextInContextAndBits.getPointer() || D == FirstDecl ||
               D == LastDecl);
}

bool setUseQualifiedLookup(bool use = true) const {
  bool old_value = DeclContextBits.UseQualifiedLookup;
  DeclContextBits.UseQualifiedLookup = use;
  return old_value;
}

bool shouldUseQualifiedLookup() const {
  return DeclContextBits.UseQualifiedLookup;
}

static bool classof(const Decl *D);
static bool classof(const DeclContext *D) { return true; }

void dumpDeclContext() const;
void dumpLookups() const;
void dumpLookups(llvm::raw_ostream &OS, bool DumpDecls = false,
                 bool Deserialize = false) const;

2479private:
/// Whether this declaration context has had externally visible
/// storage added since the last lookup. In this case, \c LookupPtr's
/// invariant may not hold and needs to be fixed before we perform
/// another lookup.
bool hasNeedToReconcileExternalVisibleStorage() const {
  return DeclContextBits.NeedToReconcileExternalVisibleStorage;
}

/// State that this declaration context has had externally visible
/// storage added since the last lookup. In this case, \c LookupPtr's
/// invariant may not hold and needs to be fixed before we perform
/// another lookup.
void setNeedToReconcileExternalVisibleStorage(bool Need = true) const {
  DeclContextBits.NeedToReconcileExternalVisibleStorage = Need;
}

/// If \c true, this context may have local lexical declarations
/// that are missing from the lookup table.
bool hasLazyLocalLexicalLookups() const {
  return DeclContextBits.HasLazyLocalLexicalLookups;
}

/// If \c true, this context may have local lexical declarations
/// that are missing from the lookup table.
void setHasLazyLocalLexicalLookups(bool HasLLLL = true) const {
  DeclContextBits.HasLazyLocalLexicalLookups = HasLLLL;
}

/// If \c true, the external source may have lexical declarations
/// that are missing from the lookup table.
bool hasLazyExternalLexicalLookups() const {
  return DeclContextBits.HasLazyExternalLexicalLookups;
}

/// If \c true, the external source may have lexical declarations
/// that are missing from the lookup table.
void setHasLazyExternalLexicalLookups(bool HasLELL = true) const {
  DeclContextBits.HasLazyExternalLexicalLookups = HasLELL;
}

void reconcileExternalVisibleStorage() const;
bool LoadLexicalDeclsFromExternalStorage() const;

/// Makes a declaration visible within this context, but
/// suppresses searches for external declarations with the same
/// name.
///
/// Analogous to makeDeclVisibleInContext, but for the exclusive
/// use of addDeclInternal().
void makeDeclVisibleInContextInternal(NamedDecl *D);

StoredDeclsMap *CreateStoredDeclsMap(ASTContext &C) const;

void loadLazyLocalLexicalLookups();
void buildLookupImpl(DeclContext *DCtx, bool Internal);
void makeDeclVisibleInContextWithFlags(NamedDecl *D, bool Internal,
                                       bool Rediscoverable);
void makeDeclVisibleInContextImpl(NamedDecl *D, bool Internal);
2538};

2540inline bool Decl::isTemplateParameter() const {
return getKind() == TemplateTypeParm || getKind() == NonTypeTemplateParm ||
       getKind() == TemplateTemplateParm;
2543}

2545// Specialization selected when ToTy is not a known subclass of DeclContext.
2546template <class ToTy,
        bool IsKnownSubtype = ::std::is_base_of<DeclContext, ToTy>::value>
2548struct cast_convert_decl_context {
static const ToTy *doit(const DeclContext *Val) {
  return static_cast<const ToTy*>(Decl::castFromDeclContext(Val));
}

static ToTy *doit(DeclContext *Val) {
  return static_cast<ToTy*>(Decl::castFromDeclContext(Val));
}
2556};

2558// Specialization selected when ToTy is a known subclass of DeclContext.
2559template <class ToTy>
2560struct cast_convert_decl_context<ToTy, true> {
static const ToTy *doit(const DeclContext *Val) {
  return static_cast<const ToTy*>(Val);
}

static ToTy *doit(DeclContext *Val) {
  return static_cast<ToTy*>(Val);
}
2568};

2570} // namespace clang

2572namespace llvm {

2574/// isa<T>(DeclContext*)
2575template <typename To>
2576struct isa_impl<To, ::clang::DeclContext> {
static bool doit(const ::clang::DeclContext &Val) {
  return To::classofKind(Val.getDeclKind());
}
2580};

2582/// cast<T>(DeclContext*)
2583template<class ToTy>
2584struct cast_convert_val<ToTy,
                      const ::clang::DeclContext,const ::clang::DeclContext> {
static const ToTy &doit(const ::clang::DeclContext &Val) {
  return *::clang::cast_convert_decl_context<ToTy>::doit(&Val);
}
2589};

2591template<class ToTy>
2592struct cast_convert_val<ToTy, ::clang::DeclContext, ::clang::DeclContext> {
static ToTy &doit(::clang::DeclContext &Val) {
  return *::clang::cast_convert_decl_context<ToTy>::doit(&Val);
}
2596};

2598template<class ToTy>
2599struct cast_convert_val<ToTy,
                   const ::clang::DeclContext*, const ::clang::DeclContext*> {
static const ToTy *doit(const ::clang::DeclContext *Val) {
  return ::clang::cast_convert_decl_context<ToTy>::doit(Val);
}
2604};

2606template<class ToTy>
2607struct cast_convert_val<ToTy, ::clang::DeclContext*, ::clang::DeclContext*> {
static ToTy *doit(::clang::DeclContext *Val) {
  return ::clang::cast_convert_decl_context<ToTy>::doit(Val);
}
2611};

2613/// Implement cast_convert_val for Decl -> DeclContext conversions.
2614template<class FromTy>
2615struct cast_convert_val< ::clang::DeclContext, FromTy, FromTy> {
static ::clang::DeclContext &doit(const FromTy &Val) {
  return *FromTy::castToDeclContext(&Val);
}
2619};

2621template<class FromTy>
2622struct cast_convert_val< ::clang::DeclContext, FromTy*, FromTy*> {
static ::clang::DeclContext *doit(const FromTy *Val) {
  return FromTy::castToDeclContext(Val);
}
2626};

2628template<class FromTy>
2629struct cast_convert_val< const ::clang::DeclContext, FromTy, FromTy> {
static const ::clang::DeclContext &doit(const FromTy &Val) {
  return *FromTy::castToDeclContext(&Val);
}
2633};

2635template<class FromTy>
2636struct cast_convert_val< const ::clang::DeclContext, FromTy*, FromTy*> {
static const ::clang::DeclContext *doit(const FromTy *Val) {
  return FromTy::castToDeclContext(Val);
}
2640};

2642} // namespace llvm

2644#endif // LLVM_CLANG_AST_DECLBASE_H