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/*
This file is part of the clazy static checker.
Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com
Author: Sérgio Martins <sergio.martins@kdab.com>
Copyright (C) 2015 Sergio Martins <smartins@kde.org>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include "unneeded-cast.h"
#include "Utils.h"
#include "QtUtils.h"
#include "TypeUtils.h"
#include "HierarchyUtils.h"
#include "ClazyContext.h"
#include <clang/AST/DeclCXX.h>
#include <clang/AST/ExprCXX.h>
using namespace llvm;
using namespace clang;
UnneededCast::UnneededCast(const std::string &name, ClazyContext *context)
: CheckBase(name, context, Option_CanIgnoreIncludes)
{
}
void UnneededCast::VisitStmt(clang::Stmt *stm)
{
if (handleNamedCast(dyn_cast<CXXNamedCastExpr>(stm)))
return;
handleQObjectCast(stm);
}
bool UnneededCast::handleNamedCast(CXXNamedCastExpr *namedCast)
{
if (!namedCast)
return false;
const bool isDynamicCast = isa<CXXDynamicCastExpr>(namedCast);
const bool isStaticCast = isDynamicCast ? false : isa<CXXStaticCastExpr>(namedCast);
if (!isDynamicCast && !isStaticCast)
return false;
if (getLocStart(namedCast).isMacroID())
return false;
CXXRecordDecl *castFrom = namedCast ? Utils::namedCastInnerDecl(namedCast) : nullptr;
if (!castFrom || !castFrom->hasDefinition() || std::distance(castFrom->bases_begin(), castFrom->bases_end()) > 1)
return false;
if (isStaticCast) {
if (auto implicitCast = dyn_cast<ImplicitCastExpr>(namedCast->getSubExpr())) {
if (implicitCast->getCastKind() == CK_NullToPointer) {
// static_cast<Foo*>(0) is OK, and sometimes needed
return false;
}
}
// static_cast to base is needed in ternary operators
if (clazy::getFirstParentOfType<ConditionalOperator>(m_context->parentMap, namedCast) != nullptr)
return false;
}
if (isDynamicCast && !isOptionSet("prefer-dynamic-cast-over-qobject") && clazy::isQObject(castFrom))
emitWarning(getLocStart(namedCast), "Use qobject_cast rather than dynamic_cast");
CXXRecordDecl *castTo = Utils::namedCastOuterDecl(namedCast);
if (!castTo)
return false;
return maybeWarn(namedCast, castFrom, castTo);
}
bool UnneededCast::handleQObjectCast(Stmt *stm)
{
CXXRecordDecl *castTo = nullptr;
CXXRecordDecl *castFrom = nullptr;
if (!clazy::is_qobject_cast(stm, &castTo, &castFrom))
return false;
return maybeWarn(stm, castFrom, castTo);
}
bool UnneededCast::maybeWarn(Stmt *stmt, CXXRecordDecl *castFrom, CXXRecordDecl *castTo)
{
castFrom = castFrom->getCanonicalDecl();
castTo = castTo->getCanonicalDecl();
if (castFrom == castTo) {
emitWarning(getLocStart(stmt), "Casting to itself");
return true;
} else if (TypeUtils::derivesFrom(/*child=*/castFrom, castTo)) {
emitWarning(getLocStart(stmt), "explicitly casting to base is unnecessary");
return true;
}
return false;
}
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