UniqueptrResetReleaseCheck.cpp
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//===--- UniqueptrResetReleaseCheck.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 "UniqueptrResetReleaseCheck.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace misc {
void UniqueptrResetReleaseCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
cxxMemberCallExpr(
on(expr().bind("left")), callee(memberExpr().bind("reset_member")),
callee(
cxxMethodDecl(hasName("reset"),
ofClass(cxxRecordDecl(hasName("::std::unique_ptr"),
decl().bind("left_class"))))),
has(ignoringParenImpCasts(cxxMemberCallExpr(
on(expr().bind("right")),
callee(memberExpr().bind("release_member")),
callee(cxxMethodDecl(
hasName("release"),
ofClass(cxxRecordDecl(hasName("::std::unique_ptr"),
decl().bind("right_class")))))))))
.bind("reset_call"),
this);
}
namespace {
const Type *getDeleterForUniquePtr(const MatchFinder::MatchResult &Result,
StringRef ID) {
const auto *Class =
Result.Nodes.getNodeAs<ClassTemplateSpecializationDecl>(ID);
if (!Class)
return nullptr;
auto DeleterArgument = Class->getTemplateArgs()[1];
if (DeleterArgument.getKind() != TemplateArgument::Type)
return nullptr;
return DeleterArgument.getAsType().getTypePtr();
}
bool areDeletersCompatible(const MatchFinder::MatchResult &Result) {
const Type *LeftDeleterType = getDeleterForUniquePtr(Result, "left_class");
const Type *RightDeleterType = getDeleterForUniquePtr(Result, "right_class");
if (LeftDeleterType->getUnqualifiedDesugaredType() ==
RightDeleterType->getUnqualifiedDesugaredType()) {
// Same type. We assume they are compatible.
// This check handles the case where the deleters are function pointers.
return true;
}
const CXXRecordDecl *LeftDeleter = LeftDeleterType->getAsCXXRecordDecl();
const CXXRecordDecl *RightDeleter = RightDeleterType->getAsCXXRecordDecl();
if (!LeftDeleter || !RightDeleter)
return false;
if (LeftDeleter->getCanonicalDecl() == RightDeleter->getCanonicalDecl()) {
// Same class. We assume they are compatible.
return true;
}
const auto *LeftAsTemplate =
dyn_cast<ClassTemplateSpecializationDecl>(LeftDeleter);
const auto *RightAsTemplate =
dyn_cast<ClassTemplateSpecializationDecl>(RightDeleter);
if (LeftAsTemplate && RightAsTemplate &&
LeftAsTemplate->getSpecializedTemplate() ==
RightAsTemplate->getSpecializedTemplate()) {
// They are different instantiations of the same template. We assume they
// are compatible.
// This handles things like std::default_delete<Base> vs.
// std::default_delete<Derived>.
return true;
}
return false;
}
} // namespace
void UniqueptrResetReleaseCheck::check(const MatchFinder::MatchResult &Result) {
if (!areDeletersCompatible(Result))
return;
const auto *ResetMember = Result.Nodes.getNodeAs<MemberExpr>("reset_member");
const auto *ReleaseMember =
Result.Nodes.getNodeAs<MemberExpr>("release_member");
const auto *Right = Result.Nodes.getNodeAs<Expr>("right");
const auto *Left = Result.Nodes.getNodeAs<Expr>("left");
const auto *ResetCall =
Result.Nodes.getNodeAs<CXXMemberCallExpr>("reset_call");
std::string LeftText = std::string(clang::Lexer::getSourceText(
CharSourceRange::getTokenRange(Left->getSourceRange()),
*Result.SourceManager, getLangOpts()));
std::string RightText = std::string(clang::Lexer::getSourceText(
CharSourceRange::getTokenRange(Right->getSourceRange()),
*Result.SourceManager, getLangOpts()));
if (ResetMember->isArrow())
LeftText = "*" + LeftText;
if (ReleaseMember->isArrow())
RightText = "*" + RightText;
std::string DiagText;
// Even if x was rvalue, *x is not rvalue anymore.
if (!Right->isRValue() || ReleaseMember->isArrow()) {
RightText = "std::move(" + RightText + ")";
DiagText = "prefer ptr1 = std::move(ptr2) over ptr1.reset(ptr2.release())";
} else {
DiagText =
"prefer ptr = ReturnUnique() over ptr.reset(ReturnUnique().release())";
}
std::string NewText = LeftText + " = " + RightText;
diag(ResetMember->getExprLoc(), DiagText) << FixItHint::CreateReplacement(
CharSourceRange::getTokenRange(ResetCall->getSourceRange()), NewText);
}
} // namespace misc
} // namespace tidy
} // namespace clang