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| //===--- ProTypeCstyleCastCheck.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 "ProTypeCstyleCastCheck.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 cppcoreguidelines {
static bool needsConstCast(QualType SourceType, QualType DestType) {
SourceType = SourceType.getNonReferenceType();
DestType = DestType.getNonReferenceType();
while (SourceType->isPointerType() && DestType->isPointerType()) {
SourceType = SourceType->getPointeeType();
DestType = DestType->getPointeeType();
if (SourceType.isConstQualified() && !DestType.isConstQualified())
return true;
}
return false;
}
void ProTypeCstyleCastCheck::registerMatchers(MatchFinder *Finder) {
if (!getLangOpts().CPlusPlus)
return;
Finder->addMatcher(
cStyleCastExpr(unless(isInTemplateInstantiation())).bind("cast"), this);
}
void ProTypeCstyleCastCheck::check(const MatchFinder::MatchResult &Result) {
const auto *MatchedCast = Result.Nodes.getNodeAs<CStyleCastExpr>("cast");
if (MatchedCast->getCastKind() == CK_BitCast ||
MatchedCast->getCastKind() == CK_LValueBitCast ||
MatchedCast->getCastKind() == CK_IntegralToPointer ||
MatchedCast->getCastKind() == CK_PointerToIntegral ||
MatchedCast->getCastKind() == CK_ReinterpretMemberPointer) {
diag(MatchedCast->getBeginLoc(),
"do not use C-style cast to convert between unrelated types");
return;
}
QualType SourceType = MatchedCast->getSubExpr()->getType();
if (MatchedCast->getCastKind() == CK_BaseToDerived) {
const auto *SourceDecl = SourceType->getPointeeCXXRecordDecl();
if (!SourceDecl) // The cast is from object to reference.
SourceDecl = SourceType->getAsCXXRecordDecl();
if (!SourceDecl)
return;
if (SourceDecl->isPolymorphic()) {
// Leave type spelling exactly as it was (unlike
// getTypeAsWritten().getAsString() which would spell enum types 'enum
// X').
StringRef DestTypeString = Lexer::getSourceText(
CharSourceRange::getTokenRange(
MatchedCast->getLParenLoc().getLocWithOffset(1),
MatchedCast->getRParenLoc().getLocWithOffset(-1)),
*Result.SourceManager, getLangOpts());
auto diag_builder = diag(
MatchedCast->getBeginLoc(),
"do not use C-style cast to downcast from a base to a derived class; "
"use dynamic_cast instead");
const Expr *SubExpr =
MatchedCast->getSubExprAsWritten()->IgnoreImpCasts();
std::string CastText = ("dynamic_cast<" + DestTypeString + ">").str();
if (!isa<ParenExpr>(SubExpr)) {
CastText.push_back('(');
diag_builder << FixItHint::CreateInsertion(
Lexer::getLocForEndOfToken(SubExpr->getEndLoc(), 0,
*Result.SourceManager, getLangOpts()),
")");
}
auto ParenRange = CharSourceRange::getTokenRange(
MatchedCast->getLParenLoc(), MatchedCast->getRParenLoc());
diag_builder << FixItHint::CreateReplacement(ParenRange, CastText);
} else {
diag(
MatchedCast->getBeginLoc(),
"do not use C-style cast to downcast from a base to a derived class");
}
return;
}
if (MatchedCast->getCastKind() == CK_NoOp &&
needsConstCast(SourceType, MatchedCast->getType())) {
diag(MatchedCast->getBeginLoc(),
"do not use C-style cast to cast away constness");
}
}
} // namespace cppcoreguidelines
} // namespace tidy
} // namespace clang
|