| //===--- UnnecessaryCopyInitialization.cpp - clang-tidy--------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "UnnecessaryCopyInitialization.h" |
| |
| #include "../utils/LexerUtils.h" |
| #include "../utils/Matchers.h" |
| |
| namespace clang { |
| namespace tidy { |
| namespace performance { |
| |
| using namespace ::clang::ast_matchers; |
| |
| namespace { |
| AST_MATCHER(QualType, isPointerType) { return Node->isPointerType(); } |
| } // namespace |
| |
| void UnnecessaryCopyInitialization::registerMatchers( |
| ast_matchers::MatchFinder *Finder) { |
| auto ConstReference = referenceType(pointee(qualType(isConstQualified()))); |
| auto ConstOrConstReference = |
| allOf(anyOf(ConstReference, isConstQualified()), |
| unless(allOf(isPointerType(), unless(pointerType(pointee(qualType( |
| isConstQualified()))))))); |
| // Match method call expressions where the this argument is a const |
| // type or const reference. This returned const reference is highly likely to |
| // outlive the local const reference of the variable being declared. |
| // The assumption is that the const reference being returned either points |
| // to a global static variable or to a member of the called object. |
| auto ConstRefReturningMethodCallOfConstParam = cxxMemberCallExpr( |
| callee(cxxMethodDecl(returns(ConstReference))), |
| on(declRefExpr(to(varDecl(hasType(qualType(ConstOrConstReference))))))); |
| auto ConstRefReturningFunctionCall = |
| callExpr(callee(functionDecl(returns(ConstReference))), |
| unless(callee(cxxMethodDecl()))); |
| Finder->addMatcher( |
| varDecl( |
| hasLocalStorage(), hasType(isConstQualified()), |
| hasType(matchers::isExpensiveToCopy()), |
| hasInitializer(cxxConstructExpr( |
| hasDeclaration(cxxConstructorDecl(isCopyConstructor())), |
| hasArgument(0, anyOf(ConstRefReturningFunctionCall, |
| ConstRefReturningMethodCallOfConstParam))))) |
| .bind("varDecl"), |
| this); |
| } |
| |
| void UnnecessaryCopyInitialization::check( |
| const ast_matchers::MatchFinder::MatchResult &Result) { |
| const auto *Var = Result.Nodes.getNodeAs<VarDecl>("varDecl"); |
| SourceLocation AmpLocation = Var->getLocation(); |
| auto Token = lexer_utils::getPreviousNonCommentToken(*Result.Context, |
| Var->getLocation()); |
| if (!Token.is(tok::unknown)) { |
| AmpLocation = Token.getLocation().getLocWithOffset(Token.getLength()); |
| } |
| diag(Var->getLocation(), |
| "the const qualified variable '%0' is copy-constructed from a " |
| "const reference; consider making it a const reference") |
| << Var->getName() << FixItHint::CreateInsertion(AmpLocation, "&"); |
| } |
| |
| } // namespace performance |
| } // namespace tidy |
| } // namespace clang |