clang-tools  4.0.0
DefinitionsInHeadersCheck.cpp
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1 //===--- DefinitionsInHeadersCheck.cpp - clang-tidy------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace misc {
19 
20 namespace {
21 
22 AST_MATCHER_P(NamedDecl, usesHeaderFileExtension,
23  utils::HeaderFileExtensionsSet, HeaderFileExtensions) {
25  Node.getLocStart(), Finder->getASTContext().getSourceManager(),
26  HeaderFileExtensions);
27 }
28 
29 } // namespace
30 
31 DefinitionsInHeadersCheck::DefinitionsInHeadersCheck(StringRef Name,
33  : ClangTidyCheck(Name, Context),
34  UseHeaderFileExtension(Options.get("UseHeaderFileExtension", true)),
35  RawStringHeaderFileExtensions(
36  Options.getLocalOrGlobal("HeaderFileExtensions", ",h,hh,hpp,hxx")) {
37  if (!utils::parseHeaderFileExtensions(RawStringHeaderFileExtensions,
38  HeaderFileExtensions, ',')) {
39  // FIXME: Find a more suitable way to handle invalid configuration
40  // options.
41  llvm::errs() << "Invalid header file extension: "
42  << RawStringHeaderFileExtensions << "\n";
43  }
44 }
45 
48  Options.store(Opts, "UseHeaderFileExtension", UseHeaderFileExtension);
49  Options.store(Opts, "HeaderFileExtensions", RawStringHeaderFileExtensions);
50 }
51 
53  if (!getLangOpts().CPlusPlus)
54  return;
55  auto DefinitionMatcher =
56  anyOf(functionDecl(isDefinition(), unless(isDeleted())),
57  varDecl(isDefinition()));
58  if (UseHeaderFileExtension) {
59  Finder->addMatcher(namedDecl(DefinitionMatcher,
60  usesHeaderFileExtension(HeaderFileExtensions))
61  .bind("name-decl"),
62  this);
63  } else {
64  Finder->addMatcher(
65  namedDecl(DefinitionMatcher,
66  anyOf(usesHeaderFileExtension(HeaderFileExtensions),
67  unless(isExpansionInMainFile())))
68  .bind("name-decl"),
69  this);
70  }
71 }
72 
73 void DefinitionsInHeadersCheck::check(const MatchFinder::MatchResult &Result) {
74  // Don't run the check in failing TUs.
75  if (Result.Context->getDiagnostics().hasErrorOccurred())
76  return;
77 
78  // C++ [basic.def.odr] p6:
79  // There can be more than one definition of a class type, enumeration type,
80  // inline function with external linkage, class template, non-static function
81  // template, static data member of a class template, member function of a
82  // class template, or template specialization for which some template
83  // parameters are not specifiedin a program provided that each definition
84  // appears in a different translation unit, and provided the definitions
85  // satisfy the following requirements.
86  const auto *ND = Result.Nodes.getNodeAs<NamedDecl>("name-decl");
87  assert(ND);
88  if (ND->isInvalidDecl())
89  return;
90 
91  // Internal linkage variable definitions are ignored for now:
92  // const int a = 1;
93  // static int b = 1;
94  //
95  // Although these might also cause ODR violations, we can be less certain and
96  // should try to keep the false-positive rate down.
97  if (ND->getLinkageInternal() == InternalLinkage)
98  return;
99 
100  if (const auto *FD = dyn_cast<FunctionDecl>(ND)) {
101  // Inline functions are allowed.
102  if (FD->isInlined())
103  return;
104  // Function templates are allowed.
105  if (FD->getTemplatedKind() == FunctionDecl::TK_FunctionTemplate)
106  return;
107  // Function template full specialization is prohibited in header file.
108  if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
109  return;
110  // Member function of a class template and member function of a nested class
111  // in a class template are allowed.
112  if (const auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
113  const auto *DC = MD->getDeclContext();
114  while (DC->isRecord()) {
115  if (const auto *RD = dyn_cast<CXXRecordDecl>(DC)) {
116  if (isa<ClassTemplatePartialSpecializationDecl>(RD))
117  return;
118  if (RD->getDescribedClassTemplate())
119  return;
120  }
121  DC = DC->getParent();
122  }
123  }
124 
125  diag(FD->getLocation(),
126  "function %0 defined in a header file; "
127  "function definitions in header files can lead to ODR violations")
128  << FD << FixItHint::CreateInsertion(
129  FD->getReturnTypeSourceRange().getBegin(), "inline ");
130  } else if (const auto *VD = dyn_cast<VarDecl>(ND)) {
131  // Static data members of a class template are allowed.
132  if (VD->getDeclContext()->isDependentContext() && VD->isStaticDataMember())
133  return;
134  if (VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
135  return;
136  // Ignore variable definition within function scope.
137  if (VD->hasLocalStorage() || VD->isStaticLocal())
138  return;
139 
140  diag(VD->getLocation(),
141  "variable %0 defined in a header file; "
142  "variable definitions in header files can lead to ODR violations")
143  << VD;
144  }
145 }
146 
147 } // namespace misc
148 } // namespace tidy
149 } // namespace clang
const std::string Name
Definition: USRFinder.cpp:164
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
LangOptions getLangOpts() const
Returns the language options from the context.
Definition: ClangTidy.h:187
bool parseHeaderFileExtensions(StringRef AllHeaderFileExtensions, HeaderFileExtensionsSet &HeaderFileExtensions, char delimiter)
Parses header file extensions from a semicolon-separated list.
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:262
bool isExpansionLocInHeaderFile(SourceLocation Loc, const SourceManager &SM, const HeaderFileExtensionsSet &HeaderFileExtensions)
Checks whether expansion location of Loc is in header file.
AST_MATCHER_P(CXXForRangeStmt, hasRangeBeginEndStmt, ast_matchers::internal::Matcher< DeclStmt >, InnerMatcher)
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
Base class for all clang-tidy checks.
Definition: ClangTidy.h:127
llvm::SmallSet< llvm::StringRef, 5 > HeaderFileExtensionsSet
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
Definition: ClangTidy.cpp:436
std::map< std::string, std::string > OptionMap
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
ClangTidyContext & Context
Definition: ClangTidy.cpp:87
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidy.cpp:403
const NamedDecl * Result
Definition: USRFinder.cpp:162