CopyConstructorInitCheck.cpp
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//===--- CopyConstructorInitCheck.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 "CopyConstructorInitCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace bugprone {
void CopyConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
if (!getLangOpts().CPlusPlus)
return;
// In the future this might be extended to move constructors?
Finder->addMatcher(
cxxConstructorDecl(
isCopyConstructor(),
hasAnyConstructorInitializer(cxxCtorInitializer(
isBaseInitializer(),
withInitializer(cxxConstructExpr(hasDeclaration(
cxxConstructorDecl(isDefaultConstructor())))))),
unless(isInstantiated()))
.bind("ctor"),
this);
}
void CopyConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
std::string ParamName = Ctor->getParamDecl(0)->getNameAsString();
// We want only one warning (and FixIt) for each ctor.
std::string FixItInitList;
bool HasRelevantBaseInit = false;
bool ShouldNotDoFixit = false;
bool HasWrittenInitializer = false;
SmallVector<FixItHint, 2> SafeFixIts;
for (const auto *Init : Ctor->inits()) {
bool CtorInitIsWritten = Init->isWritten();
HasWrittenInitializer = HasWrittenInitializer || CtorInitIsWritten;
if (!Init->isBaseInitializer())
continue;
const Type *BaseType = Init->getBaseClass();
// Do not do fixits if there is a type alias involved or one of the bases
// are explicitly initialized. In the latter case we not do fixits to avoid
// -Wreorder warnings.
if (const auto *TempSpecTy = dyn_cast<TemplateSpecializationType>(BaseType))
ShouldNotDoFixit = ShouldNotDoFixit || TempSpecTy->isTypeAlias();
ShouldNotDoFixit = ShouldNotDoFixit || isa<TypedefType>(BaseType);
ShouldNotDoFixit = ShouldNotDoFixit || CtorInitIsWritten;
const CXXRecordDecl *BaseClass =
BaseType->getAsCXXRecordDecl()->getDefinition();
if (BaseClass->field_empty() &&
BaseClass->forallBases(
[](const CXXRecordDecl *Class) { return Class->field_empty(); }))
continue;
bool NonCopyableBase = false;
for (const auto *Ctor : BaseClass->ctors()) {
if (Ctor->isCopyConstructor() &&
(Ctor->getAccess() == AS_private || Ctor->isDeleted())) {
NonCopyableBase = true;
break;
}
}
if (NonCopyableBase)
continue;
const auto *CExpr = dyn_cast<CXXConstructExpr>(Init->getInit());
if (!CExpr || !CExpr->getConstructor()->isDefaultConstructor())
continue;
HasRelevantBaseInit = true;
if (CtorInitIsWritten) {
if (!ParamName.empty())
SafeFixIts.push_back(
FixItHint::CreateInsertion(CExpr->getEndLoc(), ParamName));
} else {
if (Init->getSourceLocation().isMacroID() ||
Ctor->getLocation().isMacroID() || ShouldNotDoFixit)
break;
FixItInitList += BaseClass->getNameAsString();
FixItInitList += "(" + ParamName + "), ";
}
}
if (!HasRelevantBaseInit)
return;
auto Diag = diag(Ctor->getLocation(),
"calling a base constructor other than the copy constructor")
<< SafeFixIts;
if (FixItInitList.empty() || ParamName.empty() || ShouldNotDoFixit)
return;
std::string FixItMsg{FixItInitList.substr(0, FixItInitList.size() - 2)};
SourceLocation FixItLoc;
// There is no initialization list in this constructor.
if (!HasWrittenInitializer) {
FixItLoc = Ctor->getBody()->getBeginLoc();
FixItMsg = " : " + FixItMsg;
} else {
// We apply the missing ctors at the beginning of the initialization list.
FixItLoc = (*Ctor->init_begin())->getSourceLocation();
FixItMsg += ',';
}
FixItMsg += ' ';
Diag << FixItHint::CreateInsertion(FixItLoc, FixItMsg);
} // namespace misc
} // namespace misc
} // namespace tidy
} // namespace clang