/build/source/clang/lib/Sema/SemaCoroutine.cpp

Bug Summary

File:	build/source/clang/lib/Sema/SemaCoroutine.cpp
Warning:	line 1594, column 11 Called C++ object pointer is null
Annotated Source Code

Press '?' to see keyboard shortcuts
Show analyzer invocation
clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name SemaCoroutine.cpp -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 -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm -resource-dir /usr/lib/llvm-17/lib/clang/17 -I tools/clang/lib/Sema -I /build/source/clang/lib/Sema -I /build/source/clang/include -I tools/clang/include -I include -I /build/source/llvm/include -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -D _FORTIFY_SOURCE=2 -D NDEBUG -U 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-17/lib/clang/17/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 -fmacro-prefix-map=/build/source/build-llvm=build-llvm -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm=build-llvm -fcoverage-prefix-map=/build/source/= -O3 -Wno-unused-command-line-argument -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 -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -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-2023-05-10-133810-16478-1 -x c++ /build/source/clang/lib/Sema/SemaCoroutine.cpp
1//===-- SemaCoroutine.cpp - Semantic Analysis for Coroutines --------------===//
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 semantic analysis for C++ Coroutines.
10//
11//  This file contains references to sections of the Coroutines TS, which
12//  can be found at http://wg21.link/coroutines.
13//
14//===----------------------------------------------------------------------===//

16#include "CoroutineStmtBuilder.h"
17#include "clang/AST/ASTLambda.h"
18#include "clang/AST/Decl.h"
19#include "clang/AST/ExprCXX.h"
20#include "clang/AST/StmtCXX.h"
21#include "clang/Basic/Builtins.h"
22#include "clang/Lex/Preprocessor.h"
23#include "clang/Sema/Initialization.h"
24#include "clang/Sema/Overload.h"
25#include "clang/Sema/ScopeInfo.h"
26#include "clang/Sema/SemaInternal.h"
27#include "llvm/ADT/SmallSet.h"

29using namespace clang;
30using namespace sema;

32static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
                               SourceLocation Loc, bool &Res) {
DeclarationName DN = S.PP.getIdentifierInfo(Name);
LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
// Suppress diagnostics when a private member is selected. The same warnings
// will be produced again when building the call.
LR.suppressDiagnostics();
Res = S.LookupQualifiedName(LR, RD);
return LR;
41}

43static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
                       SourceLocation Loc) {
bool Res;
lookupMember(S, Name, RD, Loc, Res);
return Res;
48}

50/// Look up the std::coroutine_traits<...>::promise_type for the given
51/// function type.
52static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
                                SourceLocation KwLoc) {
const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
const SourceLocation FuncLoc = FD->getLocation();

ClassTemplateDecl *CoroTraits =
    S.lookupCoroutineTraits(KwLoc, FuncLoc);
if (!CoroTraits)
  return QualType();

// Form template argument list for coroutine_traits<R, P1, P2, ...> according
// to [dcl.fct.def.coroutine]3
TemplateArgumentListInfo Args(KwLoc, KwLoc);
auto AddArg = [&](QualType T) {
  Args.addArgument(TemplateArgumentLoc(
      TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
};
AddArg(FnType->getReturnType());
// If the function is a non-static member function, add the type
// of the implicit object parameter before the formal parameters.
if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
  if (MD->isInstance()) {
    // [over.match.funcs]4
    // For non-static member functions, the type of the implicit object
    // parameter is
    //  -- "lvalue reference to cv X" for functions declared without a
    //      ref-qualifier or with the & ref-qualifier
    //  -- "rvalue reference to cv X" for functions declared with the &&
    //      ref-qualifier
    QualType T = MD->getThisType()->castAs<PointerType>()->getPointeeType();
    T = FnType->getRefQualifier() == RQ_RValue
            ? S.Context.getRValueReferenceType(T)
            : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
    AddArg(T);
  }
}
for (QualType T : FnType->getParamTypes())
  AddArg(T);

// Build the template-id.
QualType CoroTrait =
    S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
if (CoroTrait.isNull())
  return QualType();
if (S.RequireCompleteType(KwLoc, CoroTrait,
                          diag::err_coroutine_type_missing_specialization))
  return QualType();

auto *RD = CoroTrait->getAsCXXRecordDecl();
assert(RD && "specialization of class template is not a class?")(static_cast <bool> (RD && "specialization of class template is not a class?"
) ? void (0) : __assert_fail ("RD && \"specialization of class template is not a class?\""
, "clang/lib/Sema/SemaCoroutine.cpp", 101, __extension__ __PRETTY_FUNCTION__
));

// Look up the ::promise_type member.
LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
               Sema::LookupOrdinaryName);
S.LookupQualifiedName(R, RD);
auto *Promise = R.getAsSingle<TypeDecl>();
if (!Promise) {
  S.Diag(FuncLoc,
         diag::err_implied_std_coroutine_traits_promise_type_not_found)
      << RD;
  return QualType();
}
// The promise type is required to be a class type.
QualType PromiseType = S.Context.getTypeDeclType(Promise);

auto buildElaboratedType = [&]() {
  auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, S.getStdNamespace());
  NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
                                    CoroTrait.getTypePtr());
  return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
};

if (!PromiseType->getAsCXXRecordDecl()) {
  S.Diag(FuncLoc,
         diag::err_implied_std_coroutine_traits_promise_type_not_class)
      << buildElaboratedType();
  return QualType();
}
if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
                          diag::err_coroutine_promise_type_incomplete))
  return QualType();

return PromiseType;
135}

137/// Look up the std::coroutine_handle<PromiseType>.
138static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
                                        SourceLocation Loc) {
if (PromiseType.isNull())
  return QualType();

NamespaceDecl *CoroNamespace = S.getStdNamespace();
assert(CoroNamespace && "Should already be diagnosed")(static_cast <bool> (CoroNamespace && "Should already be diagnosed"
) ? void (0) : __assert_fail ("CoroNamespace && \"Should already be diagnosed\""
, "clang/lib/Sema/SemaCoroutine.cpp", 144, __extension__ __PRETTY_FUNCTION__
));

LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
                    Loc, Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, CoroNamespace)) {
  S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
      << "std::coroutine_handle";
  return QualType();
}

ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
if (!CoroHandle) {
  Result.suppressDiagnostics();
  // We found something weird. Complain about the first thing we found.
  NamedDecl *Found = *Result.begin();
  S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
  return QualType();
}

// Form template argument list for coroutine_handle<Promise>.
TemplateArgumentListInfo Args(Loc, Loc);
Args.addArgument(TemplateArgumentLoc(
    TemplateArgument(PromiseType),
    S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));

// Build the template-id.
QualType CoroHandleType =
    S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
if (CoroHandleType.isNull())
  return QualType();
if (S.RequireCompleteType(Loc, CoroHandleType,
                          diag::err_coroutine_type_missing_specialization))
  return QualType();

return CoroHandleType;
179}

181static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
                                  StringRef Keyword) {
// [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within
// a function body.
// FIXME: This also covers [expr.await]p2: "An await-expression shall not
// appear in a default argument." But the diagnostic QoI here could be
// improved to inform the user that default arguments specifically are not
// allowed.
auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
if (!FD) {
  S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
                  ? diag::err_coroutine_objc_method
                  : diag::err_coroutine_outside_function) << Keyword;
  return false;
}

// An enumeration for mapping the diagnostic type to the correct diagnostic
// selection index.
enum InvalidFuncDiag {
  DiagCtor = 0,
  DiagDtor,
  DiagMain,
  DiagConstexpr,
  DiagAutoRet,
  DiagVarargs,
  DiagConsteval,
};
bool Diagnosed = false;
auto DiagInvalid = [&](InvalidFuncDiag ID) {
  S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
  Diagnosed = true;
  return false;
};

// Diagnose when a constructor, destructor
// or the function 'main' are declared as a coroutine.
auto *MD = dyn_cast<CXXMethodDecl>(FD);
// [class.ctor]p11: "A constructor shall not be a coroutine."
if (MD && isa<CXXConstructorDecl>(MD))
  return DiagInvalid(DiagCtor);
// [class.dtor]p17: "A destructor shall not be a coroutine."
else if (MD && isa<CXXDestructorDecl>(MD))
  return DiagInvalid(DiagDtor);
// [basic.start.main]p3: "The function main shall not be a coroutine."
else if (FD->isMain())
  return DiagInvalid(DiagMain);

// Emit a diagnostics for each of the following conditions which is not met.
// [expr.const]p2: "An expression e is a core constant expression unless the
// evaluation of e [...] would evaluate one of the following expressions:
// [...] an await-expression [...] a yield-expression."
if (FD->isConstexpr())
  DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr);
// [dcl.spec.auto]p15: "A function declared with a return type that uses a
// placeholder type shall not be a coroutine."
if (FD->getReturnType()->isUndeducedType())
  DiagInvalid(DiagAutoRet);
// [dcl.fct.def.coroutine]p1
// The parameter-declaration-clause of the coroutine shall not terminate with
// an ellipsis that is not part of a parameter-declaration.
if (FD->isVariadic())
  DiagInvalid(DiagVarargs);

return !Diagnosed;
245}

247/// Build a call to 'operator co_await' if there is a suitable operator for
248/// the given expression.
249ExprResult Sema::BuildOperatorCoawaitCall(SourceLocation Loc, Expr *E,
                                        UnresolvedLookupExpr *Lookup) {
UnresolvedSet<16> Functions;
Functions.append(Lookup->decls_begin(), Lookup->decls_end());
return CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
254}

256static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
                                         SourceLocation Loc, Expr *E) {
ExprResult R = SemaRef.BuildOperatorCoawaitLookupExpr(S, Loc);
if (R.isInvalid())
  return ExprError();
return SemaRef.BuildOperatorCoawaitCall(Loc, E,
                                        cast<UnresolvedLookupExpr>(R.get()));
263}

265static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
                                     SourceLocation Loc) {
QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
if (CoroHandleType.isNull())
  return ExprError();

DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
                   Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Found, LookupCtx)) {
  S.Diag(Loc, diag::err_coroutine_handle_missing_member)
      << "from_address";
  return ExprError();
}

Expr *FramePtr =
    S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_frame, {});

CXXScopeSpec SS;
ExprResult FromAddr =
    S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
if (FromAddr.isInvalid())
  return ExprError();

return S.BuildCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
290}

292struct ReadySuspendResumeResult {
enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
Expr *Results[3];
OpaqueValueExpr *OpaqueValue;
bool IsInvalid;
297};

299static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
                                StringRef Name, MultiExprArg Args) {
DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);

// FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
CXXScopeSpec SS;
ExprResult Result = S.BuildMemberReferenceExpr(
    Base, Base->getType(), Loc, /*IsPtr=*/false, SS,
    SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr,
    /*Scope=*/nullptr);
if (Result.isInvalid())
  return ExprError();

// We meant exactly what we asked for. No need for typo correction.
if (auto *TE = dyn_cast<TypoExpr>(Result.get())) {
  S.clearDelayedTypo(TE);
  S.Diag(Loc, diag::err_no_member)
      << NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
      << Base->getSourceRange();
  return ExprError();
}

return S.BuildCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
322}

324// See if return type is coroutine-handle and if so, invoke builtin coro-resume
325// on its address. This is to enable the support for coroutine-handle
326// returning await_suspend that results in a guaranteed tail call to the target
327// coroutine.
328static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
                         SourceLocation Loc) {
if (RetType->isReferenceType())
  return nullptr;
Type const *T = RetType.getTypePtr();
if (!T->isClassType() && !T->isStructureType())
  return nullptr;

// FIXME: Add convertability check to coroutine_handle<>. Possibly via
// EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
// a private function in SemaExprCXX.cpp

ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", std::nullopt);
if (AddressExpr.isInvalid())
  return nullptr;

Expr *JustAddress = AddressExpr.get();

// Check that the type of AddressExpr is void*
if (!JustAddress->getType().getTypePtr()->isVoidPointerType())
  S.Diag(cast<CallExpr>(JustAddress)->getCalleeDecl()->getLocation(),
         diag::warn_coroutine_handle_address_invalid_return_type)
      << JustAddress->getType();

// Clean up temporary objects so that they don't live across suspension points
// unnecessarily. We choose to clean up before the call to
// __builtin_coro_resume so that the cleanup code are not inserted in-between
// the resume call and return instruction, which would interfere with the
// musttail call contract.
JustAddress = S.MaybeCreateExprWithCleanups(JustAddress);
return S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_resume,
                              JustAddress);
360}

362/// Build calls to await_ready, await_suspend, and await_resume for a co_await
363/// expression.
364/// The generated AST tries to clean up temporary objects as early as
365/// possible so that they don't live across suspension points if possible.
366/// Having temporary objects living across suspension points unnecessarily can
367/// lead to large frame size, and also lead to memory corruptions if the
368/// coroutine frame is destroyed after coming back from suspension. This is done
369/// by wrapping both the await_ready call and the await_suspend call with
370/// ExprWithCleanups. In the end of this function, we also need to explicitly
371/// set cleanup state so that the CoawaitExpr is also wrapped with an
372/// ExprWithCleanups to clean up the awaiter associated with the co_await
373/// expression.
374static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
                                                SourceLocation Loc, Expr *E) {
OpaqueValueExpr *Operand = new (S.Context)
    OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);

// Assume valid until we see otherwise.
// Further operations are responsible for setting IsInalid to true.
ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/false};

using ACT = ReadySuspendResumeResult::AwaitCallType;

auto BuildSubExpr = [&](ACT CallType, StringRef Func,
                        MultiExprArg Arg) -> Expr * {
  ExprResult Result = buildMemberCall(S, Operand, Loc, Func, Arg);
  if (Result.isInvalid()) {
    Calls.IsInvalid = true;
    return nullptr;
  }
  Calls.Results[CallType] = Result.get();
  return Result.get();
};

CallExpr *AwaitReady = cast_or_null<CallExpr>(
    BuildSubExpr(ACT::ACT_Ready, "await_ready", std::nullopt));
if (!AwaitReady)
  return Calls;
if (!AwaitReady->getType()->isDependentType()) {
  // [expr.await]p3 [...]
  // — await-ready is the expression e.await_ready(), contextually converted
  // to bool.
  ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
  if (Conv.isInvalid()) {
    S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(),
           diag::note_await_ready_no_bool_conversion);
    S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
        << AwaitReady->getDirectCallee() << E->getSourceRange();
    Calls.IsInvalid = true;
  } else
    Calls.Results[ACT::ACT_Ready] = S.MaybeCreateExprWithCleanups(Conv.get());
}

ExprResult CoroHandleRes =
    buildCoroutineHandle(S, CoroPromise->getType(), Loc);
if (CoroHandleRes.isInvalid()) {
  Calls.IsInvalid = true;
  return Calls;
}
Expr *CoroHandle = CoroHandleRes.get();
CallExpr *AwaitSuspend = cast_or_null<CallExpr>(
    BuildSubExpr(ACT::ACT_Suspend, "await_suspend", CoroHandle));
if (!AwaitSuspend)
  return Calls;
if (!AwaitSuspend->getType()->isDependentType()) {
  // [expr.await]p3 [...]
  //   - await-suspend is the expression e.await_suspend(h), which shall be
  //     a prvalue of type void, bool, or std::coroutine_handle<Z> for some
  //     type Z.
  QualType RetType = AwaitSuspend->getCallReturnType(S.Context);

  // Support for coroutine_handle returning await_suspend.
  if (Expr *TailCallSuspend =
          maybeTailCall(S, RetType, AwaitSuspend, Loc))
    // Note that we don't wrap the expression with ExprWithCleanups here
    // because that might interfere with tailcall contract (e.g. inserting
    // clean up instructions in-between tailcall and return). Instead
    // ExprWithCleanups is wrapped within maybeTailCall() prior to the resume
    // call.
    Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
  else {
    // non-class prvalues always have cv-unqualified types
    if (RetType->isReferenceType() ||
        (!RetType->isBooleanType() && !RetType->isVoidType())) {
      S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
             diag::err_await_suspend_invalid_return_type)
          << RetType;
      S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
          << AwaitSuspend->getDirectCallee();
      Calls.IsInvalid = true;
    } else
      Calls.Results[ACT::ACT_Suspend] =
          S.MaybeCreateExprWithCleanups(AwaitSuspend);
  }
}

BuildSubExpr(ACT::ACT_Resume, "await_resume", std::nullopt);

// Make sure the awaiter object gets a chance to be cleaned up.
S.Cleanup.setExprNeedsCleanups(true);

return Calls;
464}

466static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
                                 SourceLocation Loc, StringRef Name,
                                 MultiExprArg Args) {

// Form a reference to the promise.
ExprResult PromiseRef = S.BuildDeclRefExpr(
    Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
if (PromiseRef.isInvalid())
  return ExprError();

return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
477}

479VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
assert(isa<FunctionDecl>(CurContext) && "not in a function scope")(static_cast <bool> (isa<FunctionDecl>(CurContext
) && "not in a function scope") ? void (0) : __assert_fail
 ("isa<FunctionDecl>(CurContext) && \"not in a function scope\""
, "clang/lib/Sema/SemaCoroutine.cpp", 480, __extension__ __PRETTY_FUNCTION__
));
auto *FD = cast<FunctionDecl>(CurContext);
bool IsThisDependentType = [&] {
  if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
    return MD->isInstance() && MD->getThisType()->isDependentType();
  else
    return false;
}();

QualType T = FD->getType()->isDependentType() || IsThisDependentType
                 ? Context.DependentTy
                 : lookupPromiseType(*this, FD, Loc);
if (T.isNull())
  return nullptr;

auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
                           &PP.getIdentifierTable().get("__promise"), T,
                           Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
VD->setImplicit();
CheckVariableDeclarationType(VD);
if (VD->isInvalidDecl())
  return nullptr;

auto *ScopeInfo = getCurFunction();

// Build a list of arguments, based on the coroutine function's arguments,
// that if present will be passed to the promise type's constructor.
llvm::SmallVector<Expr *, 4> CtorArgExprs;

// Add implicit object parameter.
if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
  if (MD->isInstance() && !isLambdaCallOperator(MD)) {
    ExprResult ThisExpr = ActOnCXXThis(Loc);
    if (ThisExpr.isInvalid())
      return nullptr;
    ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
    if (ThisExpr.isInvalid())
      return nullptr;
    CtorArgExprs.push_back(ThisExpr.get());
  }
}

// Add the coroutine function's parameters.
auto &Moves = ScopeInfo->CoroutineParameterMoves;
for (auto *PD : FD->parameters()) {
  if (PD->getType()->isDependentType())
    continue;

  auto RefExpr = ExprEmpty();
  auto Move = Moves.find(PD);
  assert(Move != Moves.end() &&(static_cast <bool> (Move != Moves.end() && "Coroutine function parameter not inserted into move map"
) ? void (0) : __assert_fail ("Move != Moves.end() && \"Coroutine function parameter not inserted into move map\""
, "clang/lib/Sema/SemaCoroutine.cpp", 531, __extension__ __PRETTY_FUNCTION__
))
         "Coroutine function parameter not inserted into move map")(static_cast <bool> (Move != Moves.end() && "Coroutine function parameter not inserted into move map"
) ? void (0) : __assert_fail ("Move != Moves.end() && \"Coroutine function parameter not inserted into move map\""
, "clang/lib/Sema/SemaCoroutine.cpp", 531, __extension__ __PRETTY_FUNCTION__
));
  // If a reference to the function parameter exists in the coroutine
  // frame, use that reference.
  auto *MoveDecl =
      cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl());
  RefExpr =
      BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
                       ExprValueKind::VK_LValue, FD->getLocation());
  if (RefExpr.isInvalid())
    return nullptr;
  CtorArgExprs.push_back(RefExpr.get());
}

// If we have a non-zero number of constructor arguments, try to use them.
// Otherwise, fall back to the promise type's default constructor.
if (!CtorArgExprs.empty()) {
  // Create an initialization sequence for the promise type using the
  // constructor arguments, wrapped in a parenthesized list expression.
  Expr *PLE = ParenListExpr::Create(Context, FD->getLocation(),
                                    CtorArgExprs, FD->getLocation());
  InitializedEntity Entity = InitializedEntity::InitializeVariable(VD);
  InitializationKind Kind = InitializationKind::CreateForInit(
      VD->getLocation(), /*DirectInit=*/true, PLE);
  InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
                                 /*TopLevelOfInitList=*/false,
                                 /*TreatUnavailableAsInvalid=*/false);

  // [dcl.fct.def.coroutine]5.7
  // promise-constructor-arguments is determined as follows: overload
  // resolution is performed on a promise constructor call created by
  // assembling an argument list  q_1 ... q_n . If a viable constructor is
  // found ([over.match.viable]), then promise-constructor-arguments is ( q_1
  // , ...,  q_n ), otherwise promise-constructor-arguments is empty.
  if (InitSeq) {
    ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs);
    if (Result.isInvalid()) {
      VD->setInvalidDecl();
    } else if (Result.get()) {
      VD->setInit(MaybeCreateExprWithCleanups(Result.get()));
      VD->setInitStyle(VarDecl::CallInit);
      CheckCompleteVariableDeclaration(VD);
    }
  } else
    ActOnUninitializedDecl(VD);
} else
  ActOnUninitializedDecl(VD);

FD->addDecl(VD);
return VD;
580}

582/// Check that this is a context in which a coroutine suspension can appear.
583static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
                                              StringRef Keyword,
                                              bool IsImplicit = false) {
if (!isValidCoroutineContext(S, Loc, Keyword))
  return nullptr;

assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope")(static_cast <bool> (isa<FunctionDecl>(S.CurContext
) && "not in a function scope") ? void (0) : __assert_fail
 ("isa<FunctionDecl>(S.CurContext) && \"not in a function scope\""
, "clang/lib/Sema/SemaCoroutine.cpp", 589, __extension__ __PRETTY_FUNCTION__
));

auto *ScopeInfo = S.getCurFunction();
assert(ScopeInfo && "missing function scope for function")(static_cast <bool> (ScopeInfo && "missing function scope for function"
) ? void (0) : __assert_fail ("ScopeInfo && \"missing function scope for function\""
, "clang/lib/Sema/SemaCoroutine.cpp", 592, __extension__ __PRETTY_FUNCTION__
));

if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
  ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);

if (ScopeInfo->CoroutinePromise)
  return ScopeInfo;

if (!S.buildCoroutineParameterMoves(Loc))
  return nullptr;

ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
if (!ScopeInfo->CoroutinePromise)
  return nullptr;

return ScopeInfo;
608}

610/// Recursively check \p E and all its children to see if any call target
611/// (including constructor call) is declared noexcept. Also any value returned
612/// from the call has a noexcept destructor.
613static void checkNoThrow(Sema &S, const Stmt *E,
                       llvm::SmallPtrSetImpl<const Decl *> &ThrowingDecls) {
auto checkDeclNoexcept = [&](const Decl *D, bool IsDtor = false) {
  // In the case of dtor, the call to dtor is implicit and hence we should
  // pass nullptr to canCalleeThrow.
  if (Sema::canCalleeThrow(S, IsDtor ? nullptr : cast<Expr>(E), D)) {
    if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
      // co_await promise.final_suspend() could end up calling
      // __builtin_coro_resume for symmetric transfer if await_suspend()
      // returns a handle. In that case, even __builtin_coro_resume is not
      // declared as noexcept and may throw, it does not throw _into_ the
      // coroutine that just suspended, but rather throws back out from
      // whoever called coroutine_handle::resume(), hence we claim that
      // logically it does not throw.
      if (FD->getBuiltinID() == Builtin::BI__builtin_coro_resume)
        return;
    }
    if (ThrowingDecls.empty()) {
      // [dcl.fct.def.coroutine]p15
      //   The expression co_await promise.final_suspend() shall not be
      //   potentially-throwing ([except.spec]).
      //
      // First time seeing an error, emit the error message.
      S.Diag(cast<FunctionDecl>(S.CurContext)->getLocation(),
             diag::err_coroutine_promise_final_suspend_requires_nothrow);
    }
    ThrowingDecls.insert(D);
  }
};

if (auto *CE = dyn_cast<CXXConstructExpr>(E)) {
  CXXConstructorDecl *Ctor = CE->getConstructor();
  checkDeclNoexcept(Ctor);
  // Check the corresponding destructor of the constructor.
  checkDeclNoexcept(Ctor->getParent()->getDestructor(), /*IsDtor=*/true);
} else if (auto *CE = dyn_cast<CallExpr>(E)) {
  if (CE->isTypeDependent())
    return;

  checkDeclNoexcept(CE->getCalleeDecl());
  QualType ReturnType = CE->getCallReturnType(S.getASTContext());
  // Check the destructor of the call return type, if any.
  if (ReturnType.isDestructedType() ==
      QualType::DestructionKind::DK_cxx_destructor) {
    const auto *T =
        cast<RecordType>(ReturnType.getCanonicalType().getTypePtr());
    checkDeclNoexcept(cast<CXXRecordDecl>(T->getDecl())->getDestructor(),
                      /*IsDtor=*/true);
  }
} else
  for (const auto *Child : E->children()) {
    if (!Child)
      continue;
    checkNoThrow(S, Child, ThrowingDecls);
  }
668}

670bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) {
llvm::SmallPtrSet<const Decl *, 4> ThrowingDecls;
// We first collect all declarations that should not throw but not declared
// with noexcept. We then sort them based on the location before printing.
// This is to avoid emitting the same note multiple times on the same
// declaration, and also provide a deterministic order for the messages.
checkNoThrow(*this, FinalSuspend, ThrowingDecls);
auto SortedDecls = llvm::SmallVector<const Decl *, 4>{ThrowingDecls.begin(),
                                                      ThrowingDecls.end()};
sort(SortedDecls, [](const Decl *A, const Decl *B) {
  return A->getEndLoc() < B->getEndLoc();
});
for (const auto *D : SortedDecls) {
  Diag(D->getEndLoc(), diag::note_coroutine_function_declare_noexcept);
}
return ThrowingDecls.empty();
686}

688bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
                                 StringRef Keyword) {
if (!checkCoroutineContext(*this, KWLoc, Keyword))
  return false;
auto *ScopeInfo = getCurFunction();
assert(ScopeInfo->CoroutinePromise)(static_cast <bool> (ScopeInfo->CoroutinePromise) ? void
 (0) : __assert_fail ("ScopeInfo->CoroutinePromise", "clang/lib/Sema/SemaCoroutine.cpp"
, 693, __extension__ __PRETTY_FUNCTION__));

// If we have existing coroutine statements then we have already built
// the initial and final suspend points.
if (!ScopeInfo->NeedsCoroutineSuspends)
  return true;

ScopeInfo->setNeedsCoroutineSuspends(false);

auto *Fn = cast<FunctionDecl>(CurContext);
SourceLocation Loc = Fn->getLocation();
// Build the initial suspend point
auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
  ExprResult Operand = buildPromiseCall(*this, ScopeInfo->CoroutinePromise,
                                        Loc, Name, std::nullopt);
  if (Operand.isInvalid())
    return StmtError();
  ExprResult Suspend =
      buildOperatorCoawaitCall(*this, SC, Loc, Operand.get());
  if (Suspend.isInvalid())
    return StmtError();
  Suspend = BuildResolvedCoawaitExpr(Loc, Operand.get(), Suspend.get(),
                                     /*IsImplicit*/ true);
  Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false);
  if (Suspend.isInvalid()) {
    Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
        << ((Name == "initial_suspend") ? 0 : 1);
    Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
    return StmtError();
  }
  return cast<Stmt>(Suspend.get());
};

StmtResult InitSuspend = buildSuspends("initial_suspend");
if (InitSuspend.isInvalid())
  return true;

StmtResult FinalSuspend = buildSuspends("final_suspend");
if (FinalSuspend.isInvalid() || !checkFinalSuspendNoThrow(FinalSuspend.get()))
  return true;

ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());

return true;
737}

739// Recursively walks up the scope hierarchy until either a 'catch' or a function
740// scope is found, whichever comes first.
741static bool isWithinCatchScope(Scope *S) {
// 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but
// lambdas that use 'co_await' are allowed. The loop below ends when a
// function scope is found in order to ensure the following behavior:
//
// void foo() {      // <- function scope
//   try {           //
//     co_await x;   // <- 'co_await' is OK within a function scope
//   } catch {       // <- catch scope
//     co_await x;   // <- 'co_await' is not OK within a catch scope
//     []() {        // <- function scope
//       co_await x; // <- 'co_await' is OK within a function scope
//     }();
//   }
// }
while (S && !S->isFunctionScope()) {
  if (S->isCatchScope())
    return true;
  S = S->getParent();
}
return false;
762}

764// [expr.await]p2, emphasis added: "An await-expression shall appear only in
765// a *potentially evaluated* expression within the compound-statement of a
766// function-body *outside of a handler* [...] A context within a function
767// where an await-expression can appear is called a suspension context of the
768// function."
769static bool checkSuspensionContext(Sema &S, SourceLocation Loc,
                                 StringRef Keyword) {
// First emphasis of [expr.await]p2: must be a potentially evaluated context.
// That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
// \c sizeof.
if (S.isUnevaluatedContext()) {
  S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
  return false;
}

// Second emphasis of [expr.await]p2: must be outside of an exception handler.
if (isWithinCatchScope(S.getCurScope())) {
  S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
  return false;
}

return true;
786}

788ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!checkSuspensionContext(*this, Loc, "co_await"))
  return ExprError();

if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
  CorrectDelayedTyposInExpr(E);
  return ExprError();
}

if (E->hasPlaceholderType()) {
  ExprResult R = CheckPlaceholderExpr(E);
  if (R.isInvalid()) return ExprError();
  E = R.get();
}
ExprResult Lookup = BuildOperatorCoawaitLookupExpr(S, Loc);
if (Lookup.isInvalid())
  return ExprError();
return BuildUnresolvedCoawaitExpr(Loc, E,
                                 cast<UnresolvedLookupExpr>(Lookup.get()));
807}

809ExprResult Sema::BuildOperatorCoawaitLookupExpr(Scope *S, SourceLocation Loc) {
DeclarationName OpName =
    Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
LookupResult Operators(*this, OpName, SourceLocation(),
                       Sema::LookupOperatorName);
LookupName(Operators, S);

assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous")(static_cast <bool> (!Operators.isAmbiguous() &&
 "Operator lookup cannot be ambiguous") ? void (0) : __assert_fail
 ("!Operators.isAmbiguous() && \"Operator lookup cannot be ambiguous\""
, "clang/lib/Sema/SemaCoroutine.cpp", 816, __extension__ __PRETTY_FUNCTION__
));
const auto &Functions = Operators.asUnresolvedSet();
bool IsOverloaded =
    Functions.size() > 1 ||
    (Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
Expr *CoawaitOp = UnresolvedLookupExpr::Create(
    Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
    DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
    Functions.begin(), Functions.end());
assert(CoawaitOp)(static_cast <bool> (CoawaitOp) ? void (0) : __assert_fail
 ("CoawaitOp", "clang/lib/Sema/SemaCoroutine.cpp", 825, __extension__
 __PRETTY_FUNCTION__));
return CoawaitOp;
827}

829// Attempts to resolve and build a CoawaitExpr from "raw" inputs, bailing out to
830// DependentCoawaitExpr if needed.
831ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *Operand,
                                          UnresolvedLookupExpr *Lookup) {
auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
if (!FSI)
  return ExprError();

if (Operand->hasPlaceholderType()) {
  ExprResult R = CheckPlaceholderExpr(Operand);
  if (R.isInvalid())
    return ExprError();
  Operand = R.get();
}

auto *Promise = FSI->CoroutinePromise;
if (Promise->getType()->isDependentType()) {
  Expr *Res = new (Context)
      DependentCoawaitExpr(Loc, Context.DependentTy, Operand, Lookup);
  return Res;
}

auto *RD = Promise->getType()->getAsCXXRecordDecl();
auto *Transformed = Operand;
if (lookupMember(*this, "await_transform", RD, Loc)) {
  ExprResult R =
      buildPromiseCall(*this, Promise, Loc, "await_transform", Operand);
  if (R.isInvalid()) {
    Diag(Loc,
         diag::note_coroutine_promise_implicit_await_transform_required_here)
        << Operand->getSourceRange();
    return ExprError();
  }
  Transformed = R.get();
}
ExprResult Awaiter = BuildOperatorCoawaitCall(Loc, Transformed, Lookup);
if (Awaiter.isInvalid())
  return ExprError();

return BuildResolvedCoawaitExpr(Loc, Operand, Awaiter.get());
869}

871ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *Operand,
                                        Expr *Awaiter, bool IsImplicit) {
auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
if (!Coroutine)
  return ExprError();

if (Awaiter->hasPlaceholderType()) {
  ExprResult R = CheckPlaceholderExpr(Awaiter);
  if (R.isInvalid()) return ExprError();
  Awaiter = R.get();
}

if (Awaiter->getType()->isDependentType()) {
  Expr *Res = new (Context)
      CoawaitExpr(Loc, Context.DependentTy, Operand, Awaiter, IsImplicit);
  return Res;
}

// If the expression is a temporary, materialize it as an lvalue so that we
// can use it multiple times.
if (Awaiter->isPRValue())
  Awaiter = CreateMaterializeTemporaryExpr(Awaiter->getType(), Awaiter, true);

// The location of the `co_await` token cannot be used when constructing
// the member call expressions since it's before the location of `Expr`, which
// is used as the start of the member call expression.
SourceLocation CallLoc = Awaiter->getExprLoc();

// Build the await_ready, await_suspend, await_resume calls.
ReadySuspendResumeResult RSS =
    buildCoawaitCalls(*this, Coroutine->CoroutinePromise, CallLoc, Awaiter);
if (RSS.IsInvalid)
  return ExprError();

Expr *Res = new (Context)
    CoawaitExpr(Loc, Operand, Awaiter, RSS.Results[0], RSS.Results[1],
                RSS.Results[2], RSS.OpaqueValue, IsImplicit);

return Res;
910}

912ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!checkSuspensionContext(*this, Loc, "co_yield"))
  return ExprError();

if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) {
  CorrectDelayedTyposInExpr(E);
  return ExprError();
}

// Build yield_value call.
ExprResult Awaitable = buildPromiseCall(
    *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
if (Awaitable.isInvalid())
  return ExprError();

// Build 'operator co_await' call.
Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
if (Awaitable.isInvalid())
  return ExprError();

return BuildCoyieldExpr(Loc, Awaitable.get());
933}
934ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
if (!Coroutine)
  return ExprError();

if (E->hasPlaceholderType()) {
  ExprResult R = CheckPlaceholderExpr(E);
  if (R.isInvalid()) return ExprError();
  E = R.get();
}

Expr *Operand = E;

if (E->getType()->isDependentType()) {
  Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, Operand, E);
  return Res;
}

// If the expression is a temporary, materialize it as an lvalue so that we
// can use it multiple times.
if (E->isPRValue())
  E = CreateMaterializeTemporaryExpr(E->getType(), E, true);

// Build the await_ready, await_suspend, await_resume calls.
ReadySuspendResumeResult RSS = buildCoawaitCalls(
    *this, Coroutine->CoroutinePromise, Loc, E);
if (RSS.IsInvalid)
  return ExprError();

Expr *Res =
    new (Context) CoyieldExpr(Loc, Operand, E, RSS.Results[0], RSS.Results[1],
                              RSS.Results[2], RSS.OpaqueValue);

return Res;
968}

970StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) {
  CorrectDelayedTyposInExpr(E);
  return StmtError();
}
return BuildCoreturnStmt(Loc, E);
976}

978StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
                                 bool IsImplicit) {
auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
if (!FSI)
  return StmtError();

if (E && E->hasPlaceholderType() &&
    !E->hasPlaceholderType(BuiltinType::Overload)) {
  ExprResult R = CheckPlaceholderExpr(E);
  if (R.isInvalid()) return StmtError();
  E = R.get();
}

VarDecl *Promise = FSI->CoroutinePromise;
ExprResult PC;
if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
  getNamedReturnInfo(E, SimplerImplicitMoveMode::ForceOn);
  PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
} else {
  E = MakeFullDiscardedValueExpr(E).get();
  PC = buildPromiseCall(*this, Promise, Loc, "return_void", std::nullopt);
}
if (PC.isInvalid())
  return StmtError();

Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get();

Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
return Res;
1007}

1009/// Look up the std::nothrow object.
1010static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
NamespaceDecl *Std = S.getStdNamespace();
assert(Std && "Should already be diagnosed")(static_cast <bool> (Std && "Should already be diagnosed"
) ? void (0) : __assert_fail ("Std && \"Should already be diagnosed\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1012, __extension__ __PRETTY_FUNCTION__
));

LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
                    Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, Std)) {
  // <coroutine> is not requred to include <new>, so we couldn't omit
  // the check here.
  S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
  return nullptr;
}

auto *VD = Result.getAsSingle<VarDecl>();
if (!VD) {
  Result.suppressDiagnostics();
  // We found something weird. Complain about the first thing we found.
  NamedDecl *Found = *Result.begin();
  S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
  return nullptr;
}

ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
if (DR.isInvalid())
  return nullptr;

return DR.get();
1037}

1039static TypeSourceInfo *getTypeSourceInfoForStdAlignValT(Sema &S,
                                                      SourceLocation Loc) {
EnumDecl *StdAlignValT = S.getStdAlignValT();
QualType StdAlignValDecl = S.Context.getTypeDeclType(StdAlignValT);
return S.Context.getTrivialTypeSourceInfo(StdAlignValDecl);
1044}

1046// Find an appropriate delete for the promise.
1047static bool findDeleteForPromise(Sema &S, SourceLocation Loc, QualType PromiseType,
                               FunctionDecl *&OperatorDelete) {
DeclarationName DeleteName =
    S.Context.DeclarationNames.getCXXOperatorName(OO_Delete);

auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
assert(PointeeRD && "PromiseType must be a CxxRecordDecl type")(static_cast <bool> (PointeeRD && "PromiseType must be a CxxRecordDecl type"
) ? void (0) : __assert_fail ("PointeeRD && \"PromiseType must be a CxxRecordDecl type\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1053, __extension__ __PRETTY_FUNCTION__
));

const bool Overaligned = S.getLangOpts().CoroAlignedAllocation;

// [dcl.fct.def.coroutine]p12
// The deallocation function's name is looked up by searching for it in the
// scope of the promise type. If nothing is found, a search is performed in
// the global scope.
if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete,
                               /*Diagnose*/ true, /*WantSize*/ true,
                               /*WantAligned*/ Overaligned))
  return false;

// [dcl.fct.def.coroutine]p12
//   If both a usual deallocation function with only a pointer parameter and a
//   usual deallocation function with both a pointer parameter and a size
//   parameter are found, then the selected deallocation function shall be the
//   one with two parameters. Otherwise, the selected deallocation function
//   shall be the function with one parameter.
if (!OperatorDelete) {
  // Look for a global declaration.
  // Coroutines can always provide their required size.
  const bool CanProvideSize = true;
  // Sema::FindUsualDeallocationFunction will try to find the one with two
  // parameters first. It will return the deallocation function with one
  // parameter if failed.
  OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize,
                                                   Overaligned, DeleteName);

  if (!OperatorDelete)
    return false;
}

S.MarkFunctionReferenced(Loc, OperatorDelete);
return true;
1088}


1091void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
FunctionScopeInfo *Fn = getCurFunction();
assert(Fn && Fn->isCoroutine() && "not a coroutine")(static_cast <bool> (Fn && Fn->isCoroutine()
 && "not a coroutine") ? void (0) : __assert_fail ("Fn && Fn->isCoroutine() && \"not a coroutine\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1093, __extension__ __PRETTY_FUNCTION__
));
1
Assuming 'Fn' is non-null→
2
←
'?' condition is true→
if (!Body) {
3
←
Assuming 'Body' is non-null→
4
←
Taking false branch→
  assert(FD->isInvalidDecl() &&(static_cast <bool> (FD->isInvalidDecl() && "a null body is only allowed for invalid declarations"
) ? void (0) : __assert_fail ("FD->isInvalidDecl() && \"a null body is only allowed for invalid declarations\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1096, __extension__ __PRETTY_FUNCTION__
))
         "a null body is only allowed for invalid declarations")(static_cast <bool> (FD->isInvalidDecl() && "a null body is only allowed for invalid declarations"
) ? void (0) : __assert_fail ("FD->isInvalidDecl() && \"a null body is only allowed for invalid declarations\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1096, __extension__ __PRETTY_FUNCTION__
));
  return;
}
// We have a function that uses coroutine keywords, but we failed to build
// the promise type.
if (!Fn->CoroutinePromise)
5
←
Assuming field 'CoroutinePromise' is non-null→
6
←
Taking false branch→
  return FD->setInvalidDecl();

if (isa<CoroutineBodyStmt>(Body)) {
7
←
Assuming 'Body' is not a 'CoroutineBodyStmt'→
8
←
Taking false branch→
  // Nothing todo. the body is already a transformed coroutine body statement.
  return;
}

// The always_inline attribute doesn't reliably apply to a coroutine,
// because the coroutine will be split into pieces and some pieces
// might be called indirectly, as in a virtual call. Even the ramp
// function cannot be inlined at -O0, due to pipeline ordering
// problems (see https://llvm.org/PR53413). Tell the user about it.
if (FD->hasAttr<AlwaysInlineAttr>())
9
←
Taking false branch→
  Diag(FD->getLocation(), diag::warn_always_inline_coroutine);

// [stmt.return.coroutine]p1:
//   A coroutine shall not enclose a return statement ([stmt.return]).
if (Fn->FirstReturnLoc.isValid()) {
10
←
Taking false branch→
  assert(Fn->FirstCoroutineStmtLoc.isValid() &&(static_cast <bool> (Fn->FirstCoroutineStmtLoc.isValid
() && "first coroutine location not set") ? void (0) :
 __assert_fail ("Fn->FirstCoroutineStmtLoc.isValid() && \"first coroutine location not set\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1121, __extension__ __PRETTY_FUNCTION__
))
                 "first coroutine location not set")(static_cast <bool> (Fn->FirstCoroutineStmtLoc.isValid
() && "first coroutine location not set") ? void (0) :
 __assert_fail ("Fn->FirstCoroutineStmtLoc.isValid() && \"first coroutine location not set\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1121, __extension__ __PRETTY_FUNCTION__
));
  Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
  Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
          << Fn->getFirstCoroutineStmtKeyword();
}

// Coroutines will get splitted into pieces. The GNU address of label
// extension wouldn't be meaningful in coroutines.
for (AddrLabelExpr *ALE : Fn->AddrLabels)
11
←
Assuming '__begin1' is equal to '__end1'→
  Diag(ALE->getBeginLoc(), diag::err_coro_invalid_addr_of_label);

CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
if (Builder.isInvalid() || !Builder.buildStatements())
12
←
Calling 'CoroutineStmtBuilder::buildStatements'→
  return FD->setInvalidDecl();

// Build body for the coroutine wrapper statement.
Body = CoroutineBodyStmt::Create(Context, Builder);
1138}

1140static CompoundStmt *buildCoroutineBody(Stmt *Body, ASTContext &Context) {
if (auto *CS = dyn_cast<CompoundStmt>(Body))
  return CS;

// The body of the coroutine may be a try statement if it is in
// 'function-try-block' syntax. Here we wrap it into a compound
// statement for consistency.
assert(isa<CXXTryStmt>(Body) && "Unimaged coroutine body type")(static_cast <bool> (isa<CXXTryStmt>(Body) &&
 "Unimaged coroutine body type") ? void (0) : __assert_fail (
"isa<CXXTryStmt>(Body) && \"Unimaged coroutine body type\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1147, __extension__ __PRETTY_FUNCTION__
));
return CompoundStmt::Create(Context, {Body}, FPOptionsOverride(),
                            SourceLocation(), SourceLocation());
1150}

1152CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
                                         sema::FunctionScopeInfo &Fn,
                                         Stmt *Body)
  : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
    IsPromiseDependentType(
        !Fn.CoroutinePromise ||
        Fn.CoroutinePromise->getType()->isDependentType()) {
this->Body = buildCoroutineBody(Body, S.getASTContext());

for (auto KV : Fn.CoroutineParameterMoves)
  this->ParamMovesVector.push_back(KV.second);
this->ParamMoves = this->ParamMovesVector;

if (!IsPromiseDependentType) {
  PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
  assert(PromiseRecordDecl && "Type should have already been checked")(static_cast <bool> (PromiseRecordDecl && "Type should have already been checked"
) ? void (0) : __assert_fail ("PromiseRecordDecl && \"Type should have already been checked\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1167, __extension__ __PRETTY_FUNCTION__
));
}
this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
1170}

1172bool CoroutineStmtBuilder::buildStatements() {
assert(this->IsValid && "coroutine already invalid")(static_cast <bool> (this->IsValid && "coroutine already invalid"
) ? void (0) : __assert_fail ("this->IsValid && \"coroutine already invalid\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1173, __extension__ __PRETTY_FUNCTION__
));
13
←
'?' condition is true→
this->IsValid = makeReturnObject();
if (this->IsValid13.1
Field 'IsValid' is true
 && !IsPromiseDependentType)
14
←
Assuming field 'IsPromiseDependentType' is false→
15
←
Taking true branch→
  buildDependentStatements();
16
←
Calling 'CoroutineStmtBuilder::buildDependentStatements'→
return this->IsValid;
1178}

1180bool CoroutineStmtBuilder::buildDependentStatements() {
assert(this->IsValid && "coroutine already invalid")(static_cast <bool> (this->IsValid && "coroutine already invalid"
) ? void (0) : __assert_fail ("this->IsValid && \"coroutine already invalid\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1181, __extension__ __PRETTY_FUNCTION__
));
17
←
'?' condition is true→
assert(!this->IsPromiseDependentType &&(static_cast <bool> (!this->IsPromiseDependentType &&
 "coroutine cannot have a dependent promise type") ? void (0)
 : __assert_fail ("!this->IsPromiseDependentType && \"coroutine cannot have a dependent promise type\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1183, __extension__ __PRETTY_FUNCTION__
))
18
←
'?' condition is true→
       "coroutine cannot have a dependent promise type")(static_cast <bool> (!this->IsPromiseDependentType &&
 "coroutine cannot have a dependent promise type") ? void (0)
 : __assert_fail ("!this->IsPromiseDependentType && \"coroutine cannot have a dependent promise type\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1183, __extension__ __PRETTY_FUNCTION__
));
this->IsValid = makeOnException() && makeOnFallthrough() &&
                makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() &&
                makeNewAndDeleteExpr();
19
←
Calling 'CoroutineStmtBuilder::makeNewAndDeleteExpr'→
return this->IsValid;
1188}

1190bool CoroutineStmtBuilder::makePromiseStmt() {
// Form a declaration statement for the promise declaration, so that AST
// visitors can more easily find it.
StmtResult PromiseStmt =
    S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc);
if (PromiseStmt.isInvalid())
  return false;

this->Promise = PromiseStmt.get();
return true;
1200}

1202bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
if (Fn.hasInvalidCoroutineSuspends())
  return false;
this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
return true;
1208}

1210static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
                                   CXXRecordDecl *PromiseRecordDecl,
                                   FunctionScopeInfo &Fn) {
auto Loc = E->getExprLoc();
if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
  auto *Decl = DeclRef->getDecl();
  if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) {
    if (Method->isStatic())
      return true;
    else
      Loc = Decl->getLocation();
  }
}

S.Diag(
    Loc,
    diag::err_coroutine_promise_get_return_object_on_allocation_failure)
    << PromiseRecordDecl;
S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
    << Fn.getFirstCoroutineStmtKeyword();
return false;
1231}

1233bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
assert(!IsPromiseDependentType &&(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1235, __extension__ __PRETTY_FUNCTION__
))
       "cannot make statement while the promise type is dependent")(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1235, __extension__ __PRETTY_FUNCTION__
));

// [dcl.fct.def.coroutine]p10
//   If a search for the name get_return_object_on_allocation_failure in
// the scope of the promise type ([class.member.lookup]) finds any
// declarations, then the result of a call to an allocation function used to
// obtain storage for the coroutine state is assumed to return nullptr if it
// fails to obtain storage, ... If the allocation function returns nullptr,
// ... and the return value is obtained by a call to
// T::get_return_object_on_allocation_failure(), where T is the
// promise type.
DeclarationName DN =
    S.PP.getIdentifierInfo("get_return_object_on_allocation_failure");
LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
  return true;

CXXScopeSpec SS;
ExprResult DeclNameExpr =
    S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
if (DeclNameExpr.isInvalid())
  return false;

if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn))
  return false;

ExprResult ReturnObjectOnAllocationFailure =
    S.BuildCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
if (ReturnObjectOnAllocationFailure.isInvalid())
  return false;

StmtResult ReturnStmt =
    S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get());
if (ReturnStmt.isInvalid()) {
  S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here)
      << DN;
  S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
      << Fn.getFirstCoroutineStmtKeyword();
  return false;
}

this->ReturnStmtOnAllocFailure = ReturnStmt.get();
return true;
1278}

1280// Collect placement arguments for allocation function of coroutine FD.
1281// Return true if we collect placement arguments succesfully. Return false,
1282// otherwise.
1283static bool collectPlacementArgs(Sema &S, FunctionDecl &FD, SourceLocation Loc,
                               SmallVectorImpl<Expr *> &PlacementArgs) {
if (auto *MD = dyn_cast<CXXMethodDecl>(&FD)) {
  if (MD->isInstance() && !isLambdaCallOperator(MD)) {
    ExprResult ThisExpr = S.ActOnCXXThis(Loc);
    if (ThisExpr.isInvalid())
      return false;
    ThisExpr = S.CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
    if (ThisExpr.isInvalid())
      return false;
    PlacementArgs.push_back(ThisExpr.get());
  }
}

for (auto *PD : FD.parameters()) {
  if (PD->getType()->isDependentType())
    continue;

  // Build a reference to the parameter.
  auto PDLoc = PD->getLocation();
  ExprResult PDRefExpr =
      S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(),
                         ExprValueKind::VK_LValue, PDLoc);
  if (PDRefExpr.isInvalid())
    return false;

  PlacementArgs.push_back(PDRefExpr.get());
}

return true;
1313}

1315bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
// Form and check allocation and deallocation calls.
assert(!IsPromiseDependentType &&(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1318, __extension__ __PRETTY_FUNCTION__
))
20
←
'?' condition is true→
       "cannot make statement while the promise type is dependent")(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1318, __extension__ __PRETTY_FUNCTION__
));
QualType PromiseType = Fn.CoroutinePromise->getType();

if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
21
←
Assuming the condition is false→
22
←
Taking false branch→
  return false;

const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
23
←
Assuming the condition is false→

// According to [dcl.fct.def.coroutine]p9, Lookup allocation functions using a
// parameter list composed of the requested size of the coroutine state being
// allocated, followed by the coroutine function's arguments. If a matching
// allocation function exists, use it. Otherwise, use an allocation function
// that just takes the requested size.
//
// [dcl.fct.def.coroutine]p9
//   An implementation may need to allocate additional storage for a
//   coroutine.
// This storage is known as the coroutine state and is obtained by calling a
// non-array allocation function ([basic.stc.dynamic.allocation]). The
// allocation function's name is looked up by searching for it in the scope of
// the promise type.
// - If any declarations are found, overload resolution is performed on a
// function call created by assembling an argument list. The first argument is
// the amount of space requested, and has type std::size_t. The
// lvalues p1 ... pn are the succeeding arguments.
//
// ...where "p1 ... pn" are defined earlier as:
//
// [dcl.fct.def.coroutine]p3
//   The promise type of a coroutine is `std::coroutine_traits<R, P1, ...,
//   Pn>`
// , where R is the return type of the function, and `P1, ..., Pn` are the
// sequence of types of the non-object function parameters, preceded by the
// type of the object parameter ([dcl.fct]) if the coroutine is a non-static
// member function. [dcl.fct.def.coroutine]p4 In the following, p_i is an
// lvalue of type P_i, where p1 denotes the object parameter and p_i+1 denotes
// the i-th non-object function parameter for a non-static member function,
// and p_i denotes the i-th function parameter otherwise. For a non-static
// member function, q_1 is an lvalue that denotes *this; any other q_i is an
// lvalue that denotes the parameter copy corresponding to p_i.

FunctionDecl *OperatorNew = nullptr;
SmallVector<Expr *, 1> PlacementArgs;

const bool PromiseContainsNew = [this, &PromiseType]() -> bool {
24
←
Calling 'operator()'→
27
←
Returning from 'operator()'→
  DeclarationName NewName =
      S.getASTContext().DeclarationNames.getCXXOperatorName(OO_New);
  LookupResult R(S, NewName, Loc, Sema::LookupOrdinaryName);

  if (PromiseType->isRecordType())
    S.LookupQualifiedName(R, PromiseType->getAsCXXRecordDecl());

  return !R.empty() && !R.isAmbiguous();
25
←
Assuming the condition is false→
26
←
Returning zero, which participates in a condition later→
}();

// Helper function to indicate whether the last lookup found the aligned
// allocation function.
bool PassAlignment = S.getLangOpts().CoroAlignedAllocation;
auto LookupAllocationFunction = [&](Sema::AllocationFunctionScope NewScope =
                                        Sema::AFS_Both,
                                    bool WithoutPlacementArgs = false,
                                    bool ForceNonAligned = false) {
  // [dcl.fct.def.coroutine]p9
  //   The allocation function's name is looked up by searching for it in the
  // scope of the promise type.
  // - If any declarations are found, ...
  // - If no declarations are found in the scope of the promise type, a search
  // is performed in the global scope.
  if (NewScope28.1
'NewScope' is equal to AFS_Both
 == Sema::AFS_Both)
    NewScope = PromiseContainsNew29.1
'PromiseContainsNew' is false
 ? Sema::AFS_Class : Sema::AFS_Global;
29
←
Taking true branch→
30
←
'?' condition is false→

  PassAlignment = !ForceNonAligned30.1
'ForceNonAligned' is false
 && S.getLangOpts().CoroAlignedAllocation;
  FunctionDecl *UnusedResult = nullptr;
  S.FindAllocationFunctions(Loc, SourceRange(), NewScope,
32
←
Value assigned to 'OperatorNew', which participates in a condition later→
                            /*DeleteScope*/ Sema::AFS_Both, PromiseType,
                            /*isArray*/ false, PassAlignment,
                            WithoutPlacementArgs30.2
'WithoutPlacementArgs' is false
 ? MultiExprArg{}
31
←
'?' condition is false→
                                                 : PlacementArgs,
                            OperatorNew, UnusedResult, /*Diagnose*/ false);
};

// We don't expect to call to global operator new with (size, p0, …, pn).
// So if we choose to lookup the allocation function in global scope, we
// shouldn't lookup placement arguments.
if (PromiseContainsNew27.1
'PromiseContainsNew' is false
 && !collectPlacementArgs(S, FD, Loc, PlacementArgs))
  return false;

LookupAllocationFunction();
28
←
Calling 'operator()'→
33
←
Returning from 'operator()'→

if (PromiseContainsNew33.1
'PromiseContainsNew' is false
 && !PlacementArgs.empty()) {
  // [dcl.fct.def.coroutine]p9
  //   If no viable function is found ([over.match.viable]), overload
  //   resolution
  // is performed again on a function call created by passing just the amount
  // of space required as an argument of type std::size_t.
  //
  // Proposed Change of [dcl.fct.def.coroutine]p9 in P2014R0:
  //   Otherwise, overload resolution is performed again on a function call
  //   created
  // by passing the amount of space requested as an argument of type
  // std::size_t as the first argument, and the requested alignment as
  // an argument of type std:align_val_t as the second argument.
  if (!OperatorNew ||
      (S.getLangOpts().CoroAlignedAllocation && !PassAlignment))
    LookupAllocationFunction(/*NewScope*/ Sema::AFS_Class,
                             /*WithoutPlacementArgs*/ true);
}

// Proposed Change of [dcl.fct.def.coroutine]p12 in P2014R0:
//   Otherwise, overload resolution is performed again on a function call
//   created
// by passing the amount of space requested as an argument of type
// std::size_t as the first argument, and the lvalues p1 ... pn as the
// succeeding arguments. Otherwise, overload resolution is performed again
// on a function call created by passing just the amount of space required as
// an argument of type std::size_t.
//
// So within the proposed change in P2014RO, the priority order of aligned
// allocation functions wiht promise_type is:
//
//    void* operator new( std::size_t, std::align_val_t, placement_args... );
//    void* operator new( std::size_t, std::align_val_t);
//    void* operator new( std::size_t, placement_args... );
//    void* operator new( std::size_t);

// Helper variable to emit warnings.
bool FoundNonAlignedInPromise = false;
if (PromiseContainsNew33.2
'PromiseContainsNew' is false
 && S.getLangOpts().CoroAlignedAllocation)
  if (!OperatorNew || !PassAlignment) {
    FoundNonAlignedInPromise = OperatorNew;

    LookupAllocationFunction(/*NewScope*/ Sema::AFS_Class,
                             /*WithoutPlacementArgs*/ false,
                             /*ForceNonAligned*/ true);

    if (!OperatorNew && !PlacementArgs.empty())
      LookupAllocationFunction(/*NewScope*/ Sema::AFS_Class,
                               /*WithoutPlacementArgs*/ true,
                               /*ForceNonAligned*/ true);
  }

bool IsGlobalOverload =
    OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext());
34
←
Assuming 'OperatorNew' is non-null→
35
←
Assuming the object is not a 'CXXRecordDecl'→
// If we didn't find a class-local new declaration and non-throwing new
// was is required then we need to lookup the non-throwing global operator
// instead.
if (RequiresNoThrowAlloc35.1
'RequiresNoThrowAlloc' is false
 && (!OperatorNew || IsGlobalOverload)) {
  auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc);
  if (!StdNoThrow)
    return false;
  PlacementArgs = {StdNoThrow};
  OperatorNew = nullptr;
  LookupAllocationFunction(Sema::AFS_Global);
}

// If we found a non-aligned allocation function in the promise_type,
// it indicates the user forgot to update the allocation function. Let's emit
// a warning here.
if (FoundNonAlignedInPromise35.2
'FoundNonAlignedInPromise' is false
) {
36
←
Taking false branch→
  S.Diag(OperatorNew->getLocation(),
         diag::warn_non_aligned_allocation_function)
      << &FD;
}

if (!OperatorNew36.1
'OperatorNew' is non-null
) {
37
←
Taking false branch→
  if (PromiseContainsNew)
    S.Diag(Loc, diag::err_coroutine_unusable_new) << PromiseType << &FD;
  else if (RequiresNoThrowAlloc)
    S.Diag(Loc, diag::err_coroutine_unfound_nothrow_new)
        << &FD << S.getLangOpts().CoroAlignedAllocation;

  return false;
}

if (RequiresNoThrowAlloc37.1
'RequiresNoThrowAlloc' is false
) {
38
←
Taking false branch→
  const auto *FT = OperatorNew->getType()->castAs<FunctionProtoType>();
  if (!FT->isNothrow(/*ResultIfDependent*/ false)) {
    S.Diag(OperatorNew->getLocation(),
           diag::err_coroutine_promise_new_requires_nothrow)
        << OperatorNew;
    S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
        << OperatorNew;
    return false;
  }
}

FunctionDecl *OperatorDelete = nullptr;
if (!findDeleteForPromise(S, Loc, PromiseType, OperatorDelete)) {
39
←
Taking false branch→
  // FIXME: We should add an error here. According to:
  // [dcl.fct.def.coroutine]p12
  //   If no usual deallocation function is found, the program is ill-formed.
  return false;
}

Expr *FramePtr =
    S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_frame, {});

Expr *FrameSize =
    S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_size, {});

Expr *FrameAlignment = nullptr;
40
←
'FrameAlignment' initialized to a null pointer value→

if (S.getLangOpts().CoroAlignedAllocation) {
41
←
Assuming field 'CoroAlignedAllocation' is 0→
42
←
Taking false branch→
  FrameAlignment =
      S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_align, {});

  TypeSourceInfo *AlignValTy = getTypeSourceInfoForStdAlignValT(S, Loc);
  if (!AlignValTy)
    return false;

  FrameAlignment = S.BuildCXXNamedCast(Loc, tok::kw_static_cast, AlignValTy,
                                       FrameAlignment, SourceRange(Loc, Loc),
                                       SourceRange(Loc, Loc))
                       .get();
}

// Make new call.
ExprResult NewRef =
    S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc);
if (NewRef.isInvalid())
43
←
Assuming the condition is false→
44
←
Taking false branch→
  return false;

SmallVector<Expr *, 2> NewArgs(1, FrameSize);
if (S.getLangOpts().CoroAlignedAllocation && PassAlignment)
45
←
Assuming field 'CoroAlignedAllocation' is 0→
  NewArgs.push_back(FrameAlignment);

if (OperatorNew->getNumParams() > NewArgs.size())
46
←
Assuming the condition is false→
47
←
Taking false branch→
  llvm::append_range(NewArgs, PlacementArgs);

ExprResult NewExpr =
    S.BuildCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false);
if (NewExpr.isInvalid())
48
←
Assuming the condition is false→
49
←
Taking false branch→
  return false;

// Make delete call.

QualType OpDeleteQualType = OperatorDelete->getType();

ExprResult DeleteRef =
    S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc);
if (DeleteRef.isInvalid())
50
←
Assuming the condition is false→
51
←
Taking false branch→
  return false;

Expr *CoroFree =
    S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_free, {FramePtr});

SmallVector<Expr *, 2> DeleteArgs{CoroFree};

// [dcl.fct.def.coroutine]p12
//   The selected deallocation function shall be called with the address of
//   the block of storage to be reclaimed as its first argument. If a
//   deallocation function with a parameter of type std::size_t is
//   used, the size of the block is passed as the corresponding argument.
const auto *OpDeleteType =
    OpDeleteQualType.getTypePtr()->castAs<FunctionProtoType>();
52
←
The object is a 'const class clang::FunctionProtoType *'→
if (OpDeleteType->getNumParams() > DeleteArgs.size() &&
53
←
Assuming the condition is true→
    S.getASTContext().hasSameUnqualifiedType(
54
←
Assuming the condition is false→
        OpDeleteType->getParamType(DeleteArgs.size()), FrameSize->getType()))
  DeleteArgs.push_back(FrameSize);

// Proposed Change of [dcl.fct.def.coroutine]p12 in P2014R0:
//   If deallocation function lookup finds a usual deallocation function with
//   a pointer parameter, size parameter and alignment parameter then this
//   will be the selected deallocation function, otherwise if lookup finds a
//   usual deallocation function with both a pointer parameter and a size
//   parameter, then this will be the selected deallocation function.
//   Otherwise, if lookup finds a usual deallocation function with only a
//   pointer parameter, then this will be the selected deallocation
//   function.
//
// So we are not forced to pass alignment to the deallocation function.
if (S.getLangOpts().CoroAlignedAllocation &&
55
←
Assuming field 'CoroAlignedAllocation' is not equal to 0→
    OpDeleteType->getNumParams() > DeleteArgs.size() &&
    S.getASTContext().hasSameUnqualifiedType(
        OpDeleteType->getParamType(DeleteArgs.size()),
        FrameAlignment->getType()))
56
←
Called C++ object pointer is null
  DeleteArgs.push_back(FrameAlignment);

ExprResult DeleteExpr =
    S.BuildCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
DeleteExpr =
    S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false);
if (DeleteExpr.isInvalid())
  return false;

this->Allocate = NewExpr.get();
this->Deallocate = DeleteExpr.get();

return true;
1608}

1610bool CoroutineStmtBuilder::makeOnFallthrough() {
assert(!IsPromiseDependentType &&(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1612, __extension__ __PRETTY_FUNCTION__
))
       "cannot make statement while the promise type is dependent")(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1612, __extension__ __PRETTY_FUNCTION__
));

// [dcl.fct.def.coroutine]/p6
// If searches for the names return_void and return_value in the scope of
// the promise type each find any declarations, the program is ill-formed.
// [Note 1: If return_void is found, flowing off the end of a coroutine is
// equivalent to a co_return with no operand. Otherwise, flowing off the end
// of a coroutine results in undefined behavior ([stmt.return.coroutine]). —
// end note]
bool HasRVoid, HasRValue;
LookupResult LRVoid =
    lookupMember(S, "return_void", PromiseRecordDecl, Loc, HasRVoid);
LookupResult LRValue =
    lookupMember(S, "return_value", PromiseRecordDecl, Loc, HasRValue);

StmtResult Fallthrough;
if (HasRVoid && HasRValue) {
  // FIXME Improve this diagnostic
  S.Diag(FD.getLocation(),
         diag::err_coroutine_promise_incompatible_return_functions)
      << PromiseRecordDecl;
  S.Diag(LRVoid.getRepresentativeDecl()->getLocation(),
         diag::note_member_first_declared_here)
      << LRVoid.getLookupName();
  S.Diag(LRValue.getRepresentativeDecl()->getLocation(),
         diag::note_member_first_declared_here)
      << LRValue.getLookupName();
  return false;
} else if (!HasRVoid && !HasRValue) {
  // We need to set 'Fallthrough'. Otherwise the other analysis part might
  // think the coroutine has defined a return_value method. So it might emit
  // **false** positive warning. e.g.,
  //
  //    promise_without_return_func foo() {
  //        co_await something();
  //    }
  //
  // Then AnalysisBasedWarning would emit a warning about `foo()` lacking a
  // co_return statements, which isn't correct.
  Fallthrough = S.ActOnNullStmt(PromiseRecordDecl->getLocation());
  if (Fallthrough.isInvalid())
    return false;
} else if (HasRVoid) {
  Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr,
                                    /*IsImplicit*/false);
  Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get());
  if (Fallthrough.isInvalid())
    return false;
}

this->OnFallthrough = Fallthrough.get();
return true;
1664}

1666bool CoroutineStmtBuilder::makeOnException() {
// Try to form 'p.unhandled_exception();'
assert(!IsPromiseDependentType &&(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1669, __extension__ __PRETTY_FUNCTION__
))
       "cannot make statement while the promise type is dependent")(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1669, __extension__ __PRETTY_FUNCTION__
));

const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;

if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) {
  auto DiagID =
      RequireUnhandledException
          ? diag::err_coroutine_promise_unhandled_exception_required
          : diag::
                warn_coroutine_promise_unhandled_exception_required_with_exceptions;
  S.Diag(Loc, DiagID) << PromiseRecordDecl;
  S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
      << PromiseRecordDecl;
  return !RequireUnhandledException;
}

// If exceptions are disabled, don't try to build OnException.
if (!S.getLangOpts().CXXExceptions)
  return true;

ExprResult UnhandledException = buildPromiseCall(
    S, Fn.CoroutinePromise, Loc, "unhandled_exception", std::nullopt);
UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc,
                                           /*DiscardedValue*/ false);
if (UnhandledException.isInvalid())
  return false;

// Since the body of the coroutine will be wrapped in try-catch, it will
// be incompatible with SEH __try if present in a function.
if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) {
  S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions);
  S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
      << Fn.getFirstCoroutineStmtKeyword();
  return false;
}

this->OnException = UnhandledException.get();
return true;
1707}

1709bool CoroutineStmtBuilder::makeReturnObject() {
// [dcl.fct.def.coroutine]p7
// The expression promise.get_return_object() is used to initialize the
// returned reference or prvalue result object of a call to a coroutine.
ExprResult ReturnObject = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
                                           "get_return_object", std::nullopt);
if (ReturnObject.isInvalid())
  return false;

this->ReturnValue = ReturnObject.get();
return true;
1720}

1722static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) {
if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(E)) {
  auto *MethodDecl = MbrRef->getMethodDecl();
  S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here)
      << MethodDecl;
}
S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
    << Fn.getFirstCoroutineStmtKeyword();
1730}

1732bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
assert(!IsPromiseDependentType &&(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1734, __extension__ __PRETTY_FUNCTION__
))
       "cannot make statement while the promise type is dependent")(static_cast <bool> (!IsPromiseDependentType &&
 "cannot make statement while the promise type is dependent")
 ? void (0) : __assert_fail ("!IsPromiseDependentType && \"cannot make statement while the promise type is dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1734, __extension__ __PRETTY_FUNCTION__
));
assert(this->ReturnValue && "ReturnValue must be already formed")(static_cast <bool> (this->ReturnValue && "ReturnValue must be already formed"
) ? void (0) : __assert_fail ("this->ReturnValue && \"ReturnValue must be already formed\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1735, __extension__ __PRETTY_FUNCTION__
));

QualType const GroType = this->ReturnValue->getType();
assert(!GroType->isDependentType() &&(static_cast <bool> (!GroType->isDependentType() &&
 "get_return_object type must no longer be dependent") ? void
 (0) : __assert_fail ("!GroType->isDependentType() && \"get_return_object type must no longer be dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1739, __extension__ __PRETTY_FUNCTION__
))
       "get_return_object type must no longer be dependent")(static_cast <bool> (!GroType->isDependentType() &&
 "get_return_object type must no longer be dependent") ? void
 (0) : __assert_fail ("!GroType->isDependentType() && \"get_return_object type must no longer be dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1739, __extension__ __PRETTY_FUNCTION__
));

QualType const FnRetType = FD.getReturnType();
assert(!FnRetType->isDependentType() &&(static_cast <bool> (!FnRetType->isDependentType() &&
 "get_return_object type must no longer be dependent") ? void
 (0) : __assert_fail ("!FnRetType->isDependentType() && \"get_return_object type must no longer be dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1743, __extension__ __PRETTY_FUNCTION__
))
       "get_return_object type must no longer be dependent")(static_cast <bool> (!FnRetType->isDependentType() &&
 "get_return_object type must no longer be dependent") ? void
 (0) : __assert_fail ("!FnRetType->isDependentType() && \"get_return_object type must no longer be dependent\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1743, __extension__ __PRETTY_FUNCTION__
));

// The call to get_­return_­object is sequenced before the call to
// initial_­suspend and is invoked at most once, but there are caveats
// regarding on whether the prvalue result object may be initialized
// directly/eager or delayed, depending on the types involved.
//
// More info at https://github.com/cplusplus/papers/issues/1414
bool GroMatchesRetType = S.getASTContext().hasSameType(GroType, FnRetType);

if (FnRetType->isVoidType()) {
  ExprResult Res =
      S.ActOnFinishFullExpr(this->ReturnValue, Loc, /*DiscardedValue*/ false);
  if (Res.isInvalid())
    return false;

  if (!GroMatchesRetType)
    this->ResultDecl = Res.get();
  return true;
}

if (GroType->isVoidType()) {
  // Trigger a nice error message.
  InitializedEntity Entity =
      InitializedEntity::InitializeResult(Loc, FnRetType);
  S.PerformCopyInitialization(Entity, SourceLocation(), ReturnValue);
  noteMemberDeclaredHere(S, ReturnValue, Fn);
  return false;
}

StmtResult ReturnStmt;
clang::VarDecl *GroDecl = nullptr;
if (GroMatchesRetType) {
  ReturnStmt = S.BuildReturnStmt(Loc, ReturnValue);
} else {
  GroDecl = VarDecl::Create(
      S.Context, &FD, FD.getLocation(), FD.getLocation(),
      &S.PP.getIdentifierTable().get("__coro_gro"), GroType,
      S.Context.getTrivialTypeSourceInfo(GroType, Loc), SC_None);
  GroDecl->setImplicit();

  S.CheckVariableDeclarationType(GroDecl);
  if (GroDecl->isInvalidDecl())
    return false;

  InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl);
  ExprResult Res =
      S.PerformCopyInitialization(Entity, SourceLocation(), ReturnValue);
  if (Res.isInvalid())
    return false;

  Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false);
  if (Res.isInvalid())
    return false;

  S.AddInitializerToDecl(GroDecl, Res.get(),
                         /*DirectInit=*/false);

  S.FinalizeDeclaration(GroDecl);

  // Form a declaration statement for the return declaration, so that AST
  // visitors can more easily find it.
  StmtResult GroDeclStmt =
      S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(GroDecl), Loc, Loc);
  if (GroDeclStmt.isInvalid())
    return false;

  this->ResultDecl = GroDeclStmt.get();

  ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc);
  if (declRef.isInvalid())
    return false;

  ReturnStmt = S.BuildReturnStmt(Loc, declRef.get());
}

if (ReturnStmt.isInvalid()) {
  noteMemberDeclaredHere(S, ReturnValue, Fn);
  return false;
}

if (!GroMatchesRetType &&
    cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl)
  GroDecl->setNRVOVariable(true);

this->ReturnStmt = ReturnStmt.get();
return true;
1830}

1832// Create a static_cast\<T&&>(expr).
1833static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) {
if (T.isNull())
  T = E->getType();
QualType TargetType = S.BuildReferenceType(
    T, /*SpelledAsLValue*/ false, SourceLocation(), DeclarationName());
SourceLocation ExprLoc = E->getBeginLoc();
TypeSourceInfo *TargetLoc =
    S.Context.getTrivialTypeSourceInfo(TargetType, ExprLoc);

return S
    .BuildCXXNamedCast(ExprLoc, tok::kw_static_cast, TargetLoc, E,
                       SourceRange(ExprLoc, ExprLoc), E->getSourceRange())
    .get();
1846}

1848/// Build a variable declaration for move parameter.
1849static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type,
                           IdentifierInfo *II) {
TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(Type, Loc);
VarDecl *Decl = VarDecl::Create(S.Context, S.CurContext, Loc, Loc, II, Type,
                                TInfo, SC_None);
Decl->setImplicit();
return Decl;
1856}

1858// Build statements that move coroutine function parameters to the coroutine
1859// frame, and store them on the function scope info.
1860bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
assert(isa<FunctionDecl>(CurContext) && "not in a function scope")(static_cast <bool> (isa<FunctionDecl>(CurContext
) && "not in a function scope") ? void (0) : __assert_fail
 ("isa<FunctionDecl>(CurContext) && \"not in a function scope\""
, "clang/lib/Sema/SemaCoroutine.cpp", 1861, __extension__ __PRETTY_FUNCTION__
));
auto *FD = cast<FunctionDecl>(CurContext);

auto *ScopeInfo = getCurFunction();
if (!ScopeInfo->CoroutineParameterMoves.empty())
  return false;

// [dcl.fct.def.coroutine]p13
//   When a coroutine is invoked, after initializing its parameters
//   ([expr.call]), a copy is created for each coroutine parameter. For a
//   parameter of type cv T, the copy is a variable of type cv T with
//   automatic storage duration that is direct-initialized from an xvalue of
//   type T referring to the parameter.
for (auto *PD : FD->parameters()) {
  if (PD->getType()->isDependentType())
    continue;

  ExprResult PDRefExpr =
      BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(),
                       ExprValueKind::VK_LValue, Loc); // FIXME: scope?
  if (PDRefExpr.isInvalid())
    return false;

  Expr *CExpr = nullptr;
  if (PD->getType()->getAsCXXRecordDecl() ||
      PD->getType()->isRValueReferenceType())
    CExpr = castForMoving(*this, PDRefExpr.get());
  else
    CExpr = PDRefExpr.get();
  // [dcl.fct.def.coroutine]p13
  //   The initialization and destruction of each parameter copy occurs in the
  //   context of the called coroutine.
  auto *D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier());
  AddInitializerToDecl(D, CExpr, /*DirectInit=*/true);

  // Convert decl to a statement.
  StmtResult Stmt = ActOnDeclStmt(ConvertDeclToDeclGroup(D), Loc, Loc);
  if (Stmt.isInvalid())
    return false;

  ScopeInfo->CoroutineParameterMoves.insert(std::make_pair(PD, Stmt.get()));
}
return true;
1904}

1906StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
if (!Res)
  return StmtError();
return Res;
1911}

1913ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc,
                                             SourceLocation FuncLoc) {
if (StdCoroutineTraitsCache)
  return StdCoroutineTraitsCache;

IdentifierInfo const &TraitIdent =
    PP.getIdentifierTable().get("coroutine_traits");

NamespaceDecl *StdSpace = getStdNamespace();
LookupResult Result(*this, &TraitIdent, FuncLoc, LookupOrdinaryName);
bool Found = StdSpace && LookupQualifiedName(Result, StdSpace);

if (!Found) {
  // The goggles, we found nothing!
  Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
      << "std::coroutine_traits";
  return nullptr;
}

// coroutine_traits is required to be a class template.
StdCoroutineTraitsCache = Result.getAsSingle<ClassTemplateDecl>();
if (!StdCoroutineTraitsCache) {
  Result.suppressDiagnostics();
  NamedDecl *Found = *Result.begin();
  Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
  return nullptr;
}

return StdCoroutineTraitsCache;
1942}