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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
// Find uses of dynamic_cast that cast between unrelated classes, which is suspicious and might
// indicate a bug. The heuristic used to consider two classes unrelated is that neither derives
// from the other (directly or indirectly) and they do not both virtually derive (directly or
// indirectly) from a common third class. Additionally, class definitions can be attributed with
// SAL_LOPLUGIN_ANNOTATE("crosscast") (from sal/types.h) to suppress false warnings about known-good
// cases casting from or to such a class.
#ifndef LO_CLANG_SHARED_PLUGINS
#include <cassert>
#include <set>
#include "compat.hxx"
#include "plugin.hxx"
namespace
{
void computeVirtualBases(CXXRecordDecl const* decl, std::set<CXXRecordDecl const*>* vbases)
{
assert(vbases != nullptr);
for (auto const& i : decl->bases())
{
auto const d = i.getType()->getAsCXXRecordDecl();
if (d == nullptr)
{
continue;
}
if (i.isVirtual())
{
if (!vbases->insert(d->getCanonicalDecl()).second)
{
// As we track the already computed virtual bases in vbases anyway, we can cheaply
// optimize the case where we see a virtual base again, even though we don't bother
// to optimize the case where we see a non-virtual base multiple times:
continue;
}
}
computeVirtualBases(d, vbases);
}
}
bool compareVirtualBases(CXXRecordDecl const* decl, std::set<CXXRecordDecl const*>& vbases)
{
for (auto const& i : decl->bases())
{
auto const d = i.getType()->getAsCXXRecordDecl();
if (d == nullptr)
{
continue;
}
if (i.isVirtual() && vbases.count(d->getCanonicalDecl()) == 1)
{
return true;
}
if (compareVirtualBases(d, vbases))
{
return true;
}
}
return false;
}
bool haveCommonVirtualBase(CXXRecordDecl const* decl1, CXXRecordDecl const* decl2)
{
std::set<CXXRecordDecl const*> vbases;
computeVirtualBases(decl1, &vbases);
return compareVirtualBases(decl2, vbases);
}
bool isAllowedInCrossCasts(CXXRecordDecl const* decl)
{
auto const def = decl->getDefinition();
if (def == nullptr)
{
return false;
}
for (auto const attr : def->specific_attrs<AnnotateAttr>())
{
if (attr->getAnnotation() == "loplugin:crosscast")
{
return true;
}
}
return false;
}
class CrossCast final : public loplugin::FilteringPlugin<CrossCast>
{
public:
explicit CrossCast(loplugin::InstantiationData const& data)
: FilteringPlugin(data)
{
}
bool preRun() override { return compiler.getLangOpts().CPlusPlus; }
void run() override
{
if (preRun())
{
TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
}
}
bool VisitCXXDynamicCastExpr(CXXDynamicCastExpr const* expr)
{
if (ignoreLocation(expr))
{
return true;
}
auto const t2 = expr->getTypeAsWritten();
if (t2->isVoidPointerType())
{
return true;
}
auto const d2 = t2->getPointeeCXXRecordDecl();
if (d2 == nullptr)
{
return true;
}
auto const t1 = compat::getSubExprAsWritten(expr)->getType();
auto t1a = t1;
if (auto const t = t1a->getAs<clang::PointerType>())
{
t1a = t->getPointeeType();
}
auto const d1 = t1a->getAsCXXRecordDecl();
if (d1 == nullptr)
{
return true;
}
if (d1->getCanonicalDecl() == d2->getCanonicalDecl() || d1->isDerivedFrom(d2)
|| d2->isDerivedFrom(d1) || haveCommonVirtualBase(d1, d2))
{
return true;
}
if (isAllowedInCrossCasts(d1) || isAllowedInCrossCasts(d2))
{
return true;
}
if (suppressWarningAt(expr->getBeginLoc()))
{
return true;
}
report(DiagnosticsEngine::Warning, "suspicious dynamic cross cast from %0 to %1",
expr->getExprLoc())
<< t1 << t2 << expr->getSourceRange();
return true;
}
};
loplugin::Plugin::Registration<CrossCast> crosscast("crosscast");
}
#endif
/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
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