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//===--- ReferenceToConstructedTemporaryCheck.cpp - clang-tidy
//--------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ReferenceToConstructedTemporaryCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang::tidy::readability {
namespace {
// Predicate structure to check if lifetime of temporary is not extended by
// ValueDecl pointed out by ID
struct NotExtendedByDeclBoundToPredicate {
bool operator()(const internal::BoundNodesMap &Nodes) const {
const auto *Other = Nodes.getNodeAs<ValueDecl>(ID);
if (!Other)
return true;
const auto *Self = Node.get<MaterializeTemporaryExpr>();
if (!Self)
return true;
return Self->getExtendingDecl() != Other;
}
StringRef ID;
::clang::DynTypedNode Node;
};
AST_MATCHER_P(MaterializeTemporaryExpr, isExtendedByDeclBoundTo, StringRef,
ID) {
NotExtendedByDeclBoundToPredicate Predicate{
ID, ::clang::DynTypedNode::create(Node)};
return Builder->removeBindings(Predicate);
}
} // namespace
bool ReferenceToConstructedTemporaryCheck::isLanguageVersionSupported(
const LangOptions &LangOpts) const {
return LangOpts.CPlusPlus;
}
std::optional<TraversalKind>
ReferenceToConstructedTemporaryCheck::getCheckTraversalKind() const {
return TK_AsIs;
}
void ReferenceToConstructedTemporaryCheck::registerMatchers(
MatchFinder *Finder) {
Finder->addMatcher(
varDecl(unless(isExpansionInSystemHeader()),
hasType(qualType(references(qualType().bind("type")))),
decl().bind("var"),
hasInitializer(expr(hasDescendant(
materializeTemporaryExpr(
isExtendedByDeclBoundTo("var"),
has(expr(anyOf(cxxTemporaryObjectExpr(), initListExpr(),
cxxConstructExpr()),
hasType(qualType(equalsBoundNode("type"))))))
.bind("temporary"))))),
this);
}
void ReferenceToConstructedTemporaryCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("var");
const auto *MatchedTemporary = Result.Nodes.getNodeAs<Expr>("temporary");
diag(MatchedDecl->getLocation(),
"reference variable %0 extends the lifetime of a just-constructed "
"temporary object %1, consider changing reference to value")
<< MatchedDecl << MatchedTemporary->getType();
}
} // namespace clang::tidy::readability
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