llvm-project/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp

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4.1 KiB
C++

//===--- UseEmplaceCheck.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 "UseEmplaceCheck.h"
#include "../utils/Matchers.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace modernize {
void UseEmplaceCheck::registerMatchers(MatchFinder *Finder) {
if (!getLangOpts().CPlusPlus11)
return;
// FIXME: Bunch of functionality that could be easily added:
// + add handling of `push_front` for std::forward_list, std::list
// and std::deque.
// + add handling of `push` for std::stack, std::queue, std::priority_queue
// + add handling of `insert` for stl associative container, but be careful
// because this requires special treatment (it could cause performance
// regression)
// + match for emplace calls that should be replaced with insertion
// + match for make_pair calls.
auto callPushBack = cxxMemberCallExpr(
hasDeclaration(functionDecl(hasName("push_back"))),
on(hasType(cxxRecordDecl(hasAnyName("std::vector", "llvm::SmallVector",
"std::list", "std::deque")))));
// We can't replace push_backs of smart pointer because
// if emplacement fails (f.e. bad_alloc in vector) we will have leak of
// passed pointer because smart pointer won't be constructed
// (and destructed) as in push_back case.
auto isCtorOfSmartPtr = hasDeclaration(cxxConstructorDecl(
ofClass(hasAnyName("std::shared_ptr", "std::unique_ptr", "std::auto_ptr",
"std::weak_ptr"))));
// Bitfields binds only to consts and emplace_back take it by universal ref.
auto bitFieldAsArgument = hasAnyArgument(ignoringParenImpCasts(
memberExpr(hasDeclaration(fieldDecl(matchers::isBitfield())))));
// We could have leak of resource.
auto newExprAsArgument = hasAnyArgument(ignoringParenImpCasts(cxxNewExpr()));
auto constructingDerived =
hasParent(implicitCastExpr(hasCastKind(CastKind::CK_DerivedToBase)));
auto hasInitList = has(ignoringParenImpCasts(initListExpr()));
auto soughtConstructExpr =
cxxConstructExpr(
unless(anyOf(isCtorOfSmartPtr, hasInitList, bitFieldAsArgument,
newExprAsArgument, constructingDerived,
has(materializeTemporaryExpr(hasInitList)))))
.bind("ctor");
auto hasConstructExpr = has(ignoringParenImpCasts(soughtConstructExpr));
auto ctorAsArgument = materializeTemporaryExpr(
anyOf(hasConstructExpr, has(cxxFunctionalCastExpr(hasConstructExpr))));
Finder->addMatcher(
cxxMemberCallExpr(callPushBack, has(ctorAsArgument)).bind("call"), this);
}
void UseEmplaceCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Call = Result.Nodes.getNodeAs<CXXMemberCallExpr>("call");
const auto *InnerCtorCall = Result.Nodes.getNodeAs<CXXConstructExpr>("ctor");
auto FunctionNameSourceRange = CharSourceRange::getCharRange(
Call->getExprLoc(), Call->getArg(0)->getExprLoc());
auto Diag = diag(Call->getExprLoc(), "use emplace_back instead of push_back");
if (FunctionNameSourceRange.getBegin().isMacroID())
return;
Diag << FixItHint::CreateReplacement(FunctionNameSourceRange,
"emplace_back(");
auto CallParensRange = InnerCtorCall->getParenOrBraceRange();
// Finish if there is no explicit constructor call.
if (CallParensRange.getBegin().isInvalid())
return;
// Range for constructor name and opening brace.
auto CtorCallSourceRange = CharSourceRange::getCharRange(
InnerCtorCall->getExprLoc(),
CallParensRange.getBegin().getLocWithOffset(1));
Diag << FixItHint::CreateRemoval(CtorCallSourceRange)
<< FixItHint::CreateRemoval(CharSourceRange::getCharRange(
CallParensRange.getEnd(),
CallParensRange.getEnd().getLocWithOffset(1)));
}
} // namespace modernize
} // namespace tidy
} // namespace clang