1 //===--- UnusedLocalNonTrivialVariableCheck.cpp - clang-tidy --------------===// 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 #include "UnusedLocalNonTrivialVariableCheck.h" 10 #include "../utils/Matchers.h" 11 #include "../utils/OptionsUtils.h" 12 #include "clang/AST/ASTContext.h" 13 #include "clang/AST/ASTTypeTraits.h" 14 #include "clang/AST/Type.h" 15 #include "clang/ASTMatchers/ASTMatchFinder.h" 16 #include "clang/ASTMatchers/ASTMatchers.h" 17 #include "clang/ASTMatchers/ASTMatchersMacros.h" 18 #include "clang/Basic/LangOptions.h" 19 20 using namespace clang::ast_matchers; 21 using namespace clang::tidy::matchers; 22 23 namespace clang::tidy::bugprone { 24 25 namespace { 26 static constexpr StringRef DefaultIncludeTypeRegex = 27 "::std::.*mutex;::std::future;::std::basic_string;::std::basic_regex;" 28 "::std::basic_istringstream;::std::basic_stringstream;::std::bitset;" 29 "::std::filesystem::path"; 30 31 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); } 32 AST_MATCHER(VarDecl, isReferenced) { return Node.isReferenced(); } 33 AST_MATCHER(VarDecl, explicitMarkUnused) { 34 // Implementations should not emit a warning that a name-independent 35 // declaration is used or unused. 36 LangOptions const &LangOpts = Finder->getASTContext().getLangOpts(); 37 return Node.hasAttr<UnusedAttr>() || 38 (LangOpts.CPlusPlus26 && Node.isPlaceholderVar(LangOpts)); 39 } 40 AST_MATCHER(Type, isReferenceType) { return Node.isReferenceType(); } 41 AST_MATCHER(QualType, isTrivial) { 42 return Node.isTrivialType(Finder->getASTContext()) || 43 Node.isTriviallyCopyableType(Finder->getASTContext()); 44 } 45 } // namespace 46 47 UnusedLocalNonTrivialVariableCheck::UnusedLocalNonTrivialVariableCheck( 48 StringRef Name, ClangTidyContext *Context) 49 : ClangTidyCheck(Name, Context), 50 IncludeTypes(utils::options::parseStringList( 51 Options.get("IncludeTypes", DefaultIncludeTypeRegex))), 52 ExcludeTypes( 53 utils::options::parseStringList(Options.get("ExcludeTypes", ""))) {} 54 55 void UnusedLocalNonTrivialVariableCheck::storeOptions( 56 ClangTidyOptions::OptionMap &Opts) { 57 Options.store(Opts, "IncludeTypes", 58 utils::options::serializeStringList(IncludeTypes)); 59 Options.store(Opts, "ExcludeTypes", 60 utils::options::serializeStringList(ExcludeTypes)); 61 } 62 63 void UnusedLocalNonTrivialVariableCheck::registerMatchers(MatchFinder *Finder) { 64 if (IncludeTypes.empty()) 65 return; 66 67 Finder->addMatcher( 68 varDecl(isLocalVarDecl(), unless(isReferenced()), 69 unless(isExceptionVariable()), hasLocalStorage(), isDefinition(), 70 unless(hasType(isReferenceType())), unless(hasType(isTrivial())), 71 unless(explicitMarkUnused()), 72 hasType(hasUnqualifiedDesugaredType( 73 anyOf(recordType(hasDeclaration(namedDecl( 74 matchesAnyListedName(IncludeTypes), 75 unless(matchesAnyListedName(ExcludeTypes))))), 76 templateSpecializationType(hasDeclaration(namedDecl( 77 matchesAnyListedName(IncludeTypes), 78 unless(matchesAnyListedName(ExcludeTypes))))))))) 79 .bind("var"), 80 this); 81 } 82 83 void UnusedLocalNonTrivialVariableCheck::check( 84 const MatchFinder::MatchResult &Result) { 85 const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("var"); 86 diag(MatchedDecl->getLocation(), "unused local variable %0 of type %1") 87 << MatchedDecl << MatchedDecl->getType(); 88 } 89 90 bool UnusedLocalNonTrivialVariableCheck::isLanguageVersionSupported( 91 const LangOptions &LangOpts) const { 92 return LangOpts.CPlusPlus; 93 } 94 95 std::optional<TraversalKind> 96 UnusedLocalNonTrivialVariableCheck::getCheckTraversalKind() const { 97 return TK_IgnoreUnlessSpelledInSource; 98 } 99 100 } // namespace clang::tidy::bugprone 101