MisplacedConstCheck.cpp
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//===--- MisplacedConstCheck.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 "MisplacedConstCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace misc {
void MisplacedConstCheck::registerMatchers(MatchFinder *Finder) {
auto NonConstAndNonFunctionPointerType = hasType(pointerType(unless(
pointee(anyOf(isConstQualified(), ignoringParens(functionType()))))));
Finder->addMatcher(
valueDecl(
hasType(isConstQualified()),
hasType(typedefType(hasDeclaration(anyOf(
typedefDecl(NonConstAndNonFunctionPointerType).bind("typedef"),
typeAliasDecl(NonConstAndNonFunctionPointerType)
.bind("typeAlias"))))))
.bind("decl"),
this);
}
static QualType guessAlternateQualification(ASTContext &Context, QualType QT) {
// We're given a QualType from a typedef where the qualifiers apply to the
// pointer instead of the pointee. Strip the const qualifier from the pointer
// type and add it to the pointee instead.
if (!QT->isPointerType())
return QT;
Qualifiers Quals = QT.getLocalQualifiers();
Quals.removeConst();
QualType NewQT = Context.getPointerType(
QualType(QT->getPointeeType().getTypePtr(), Qualifiers::Const));
return NewQT.withCVRQualifiers(Quals.getCVRQualifiers());
}
void MisplacedConstCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Var = Result.Nodes.getNodeAs<ValueDecl>("decl");
ASTContext &Ctx = *Result.Context;
QualType CanQT = Var->getType().getCanonicalType();
SourceLocation AliasLoc;
const char *AliasType;
if (const auto *Typedef = Result.Nodes.getNodeAs<TypedefDecl>("typedef")) {
AliasLoc = Typedef->getLocation();
AliasType = "typedef";
} else if (const auto *TypeAlias =
Result.Nodes.getNodeAs<TypeAliasDecl>("typeAlias")) {
AliasLoc = TypeAlias->getLocation();
AliasType = "type alias";
} else {
llvm_unreachable("registerMatchers has registered an unknown matcher,"
" code out of sync");
}
diag(Var->getLocation(), "%0 declared with a const-qualified %1; "
"results in the type being '%2' instead of '%3'")
<< Var << AliasType << CanQT.getAsString(Ctx.getPrintingPolicy())
<< guessAlternateQualification(Ctx, CanQT)
.getAsString(Ctx.getPrintingPolicy());
diag(AliasLoc, "%0 declared here", DiagnosticIDs::Note) << AliasType;
}
} // namespace misc
} // namespace tidy
} // namespace clang