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