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//===--- MoveConstructorInitCheck.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 "MoveConstructorInitCheck.h"
#include "../utils/Matchers.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/Lexer.h"
#include "clang/Lex/Preprocessor.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace misc {
namespace {
unsigned int
parmVarDeclRefExprOccurences(const ParmVarDecl &MovableParam,
const CXXConstructorDecl &ConstructorDecl,
ASTContext &Context) {
unsigned int Occurrences = 0;
auto AllDeclRefs =
findAll(declRefExpr(to(parmVarDecl(equalsNode(&MovableParam)))));
Occurrences += match(AllDeclRefs, *ConstructorDecl.getBody(), Context).size();
for (const auto *Initializer : ConstructorDecl.inits()) {
Occurrences += match(AllDeclRefs, *Initializer->getInit(), Context).size();
}
return Occurrences;
}
} // namespace
MoveConstructorInitCheck::MoveConstructorInitCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
IncludeStyle(utils::IncludeSorter::parseIncludeStyle(
Options.get("IncludeStyle", "llvm"))),
UseCERTSemantics(Options.get("UseCERTSemantics", 0) != 0) {}
void MoveConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
// Only register the matchers for C++11; the functionality currently does not
// provide any benefit to other languages, despite being benign.
if (!getLangOpts().CPlusPlus11)
return;
Finder->addMatcher(
cxxConstructorDecl(
unless(isImplicit()),
allOf(isMoveConstructor(),
hasAnyConstructorInitializer(
cxxCtorInitializer(
withInitializer(cxxConstructExpr(hasDeclaration(
cxxConstructorDecl(isCopyConstructor())
.bind("ctor")))))
.bind("move-init")))),
this);
auto NonConstValueMovableAndExpensiveToCopy =
qualType(allOf(unless(pointerType()), unless(isConstQualified()),
hasDeclaration(cxxRecordDecl(hasMethod(cxxConstructorDecl(
isMoveConstructor(), unless(isDeleted()))))),
matchers::isExpensiveToCopy()));
// This checker is also used to implement cert-oop11-cpp, but when using that
// form of the checker, we do not want to diagnose movable parameters.
if (!UseCERTSemantics) {
Finder->addMatcher(
cxxConstructorDecl(
allOf(
unless(isMoveConstructor()),
hasAnyConstructorInitializer(withInitializer(cxxConstructExpr(
hasDeclaration(cxxConstructorDecl(isCopyConstructor())),
hasArgument(
0,
declRefExpr(
to(parmVarDecl(
hasType(
NonConstValueMovableAndExpensiveToCopy))
.bind("movable-param")))
.bind("init-arg")))))))
.bind("ctor-decl"),
this);
}
}
void MoveConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
if (Result.Nodes.getNodeAs<CXXCtorInitializer>("move-init") != nullptr)
handleMoveConstructor(Result);
if (Result.Nodes.getNodeAs<ParmVarDecl>("movable-param") != nullptr)
handleParamNotMoved(Result);
}
void MoveConstructorInitCheck::handleParamNotMoved(
const MatchFinder::MatchResult &Result) {
const auto *MovableParam =
Result.Nodes.getNodeAs<ParmVarDecl>("movable-param");
const auto *ConstructorDecl =
Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor-decl");
const auto *InitArg = Result.Nodes.getNodeAs<DeclRefExpr>("init-arg");
// If the parameter is referenced more than once it is not safe to move it.
if (parmVarDeclRefExprOccurences(*MovableParam, *ConstructorDecl,
*Result.Context) > 1)
return;
auto DiagOut = diag(InitArg->getLocStart(),
"value argument %0 can be moved to avoid copy")
<< MovableParam;
DiagOut << FixItHint::CreateReplacement(
InitArg->getSourceRange(),
(Twine("std::move(") + MovableParam->getName() + ")").str());
if (auto IncludeFixit = Inserter->CreateIncludeInsertion(
Result.SourceManager->getFileID(InitArg->getLocStart()), "utility",
/*IsAngled=*/true)) {
DiagOut << *IncludeFixit;
}
}
void MoveConstructorInitCheck::handleMoveConstructor(
const MatchFinder::MatchResult &Result) {
const auto *CopyCtor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
const auto *Initializer = Result.Nodes.getNodeAs<CXXCtorInitializer>("move-init");
// Do not diagnose if the expression used to perform the initialization is a
// trivially-copyable type.
QualType QT = Initializer->getInit()->getType();
if (QT.isTriviallyCopyableType(*Result.Context))
return;
const auto *RD = QT->getAsCXXRecordDecl();
if (RD && RD->isTriviallyCopyable())
return;
// Diagnose when the class type has a move constructor available, but the
// ctor-initializer uses the copy constructor instead.
const CXXConstructorDecl *Candidate = nullptr;
for (const auto *Ctor : CopyCtor->getParent()->ctors()) {
if (Ctor->isMoveConstructor() && Ctor->getAccess() <= AS_protected &&
!Ctor->isDeleted()) {
// The type has a move constructor that is at least accessible to the
// initializer.
//
// FIXME: Determine whether the move constructor is a viable candidate
// for the ctor-initializer, perhaps provide a fixit that suggests
// using std::move().
Candidate = Ctor;
break;
}
}
if (Candidate) {
// There's a move constructor candidate that the caller probably intended
// to call instead.
diag(Initializer->getSourceLocation(),
"move constructor initializes %0 by calling a copy constructor")
<< (Initializer->isBaseInitializer() ? "base class" : "class member");
diag(CopyCtor->getLocation(), "copy constructor being called",
DiagnosticIDs::Note);
diag(Candidate->getLocation(), "candidate move constructor here",
DiagnosticIDs::Note);
}
}
void MoveConstructorInitCheck::registerPPCallbacks(CompilerInstance &Compiler) {
Inserter.reset(new utils::IncludeInserter(
Compiler.getSourceManager(), Compiler.getLangOpts(), IncludeStyle));
Compiler.getPreprocessor().addPPCallbacks(Inserter->CreatePPCallbacks());
}
void MoveConstructorInitCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "IncludeStyle",
utils::IncludeSorter::toString(IncludeStyle));
Options.store(Opts, "UseCERTSemantics", UseCERTSemantics ? 1 : 0);
}
} // namespace misc
} // namespace tidy
} // namespace clang
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