8f4fdb405a
...to complement and improve upon GCC's -Wclass-memaccess. See the comment at the head of compilerplugins/clang/classmemaccess.cxx for details. (It is not yet clear to me whether we would want to get this upstreamed into Clang.) 35d21e4bf6f66b3bbc7a44fcf184cb721b524a94 "Remove redundant memsets" was a case that benefited from looking through toplevel casts to void*. (Though the code in include/basic/sbxvar.hxx needs a slightly more verbose way to deliberately silence the warning now.) d03041e19215592f21ba1222d3cfa29e1f94260a "Drop bogus memsets" is one example of various cases that GCC -Wclass-memaccess failed to catch due to the use of array instead of pointer types. Change-Id: I6a9bfc34e3536834af35fdf4fb7ceeb31f31f8c0 Reviewed-on: https://gerrit.libreoffice.org/80421 Tested-by: Jenkins Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
134 lines
4.3 KiB
C++
134 lines
4.3 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#ifndef LO_CLANG_SHARED_PLUGINS
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#include "check.hxx"
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#include "plugin.hxx"
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// Similar to GCC "warning: ‘void* memset(void*, int, size_t)’ writing to an object of non-trivial
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// type ‘...’; use assignment instead [-Wclass-memaccess]", but looking through toplevel cast to
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// void* and taking arrays into account in addition to pointers. (Clang has
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// -Wdynamic-class-memaccess, but that only warns about memset overwriting a vtable pointer. GCC
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// deliberately does not warn when there is a toplevel cast to void*, see
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// <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81327> "[8 Regression] cast to void* does not
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// suppress -Wclass-memaccess".)
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namespace
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{
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class ClassMemAccess final : public loplugin::FilteringPlugin<ClassMemAccess>
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{
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public:
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explicit ClassMemAccess(loplugin::InstantiationData const& data)
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: FilteringPlugin(data)
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{
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}
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bool VisitCallExpr(CallExpr* expr)
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{
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if (ignoreLocation(expr))
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{
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return true;
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}
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auto const fdecl = expr->getDirectCallee();
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if (fdecl == nullptr)
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{
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return true;
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}
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auto dc = loplugin::DeclCheck(fdecl).Function("memset");
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if (!(dc.GlobalNamespace() || dc.StdNamespace()))
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{
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return true;
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}
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if (expr->getNumArgs() != 3)
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{
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if (isDebugMode())
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{
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report(DiagnosticsEngine::Fatal,
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"unexpected call to %0 with %1 instead of 3 arguments", expr->getExprLoc())
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<< fdecl << expr->getNumArgs() << expr->getSourceRange();
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report(DiagnosticsEngine::Note, "%0 declared here", fdecl->getLocation())
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<< fdecl << fdecl->getSourceRange();
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}
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return true;
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}
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auto e = expr->getArg(0)->IgnoreParenImpCasts();
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while (auto const cast = dyn_cast<ExplicitCastExpr>(e))
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{
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if (!loplugin::TypeCheck(cast->getTypeAsWritten()).Pointer().Void())
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{
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break;
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}
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e = cast->getSubExprAsWritten()->IgnoreParenImpCasts();
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}
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QualType t;
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if (auto const t1 = e->getType()->getAs<clang::PointerType>())
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{
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t = t1->getPointeeType();
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}
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else if (e->getType()->isArrayType())
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{
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t = e->getType();
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while (auto const t2 = t->getAsArrayTypeUnsafe())
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{
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t = t2->getElementType();
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}
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}
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else
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{
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if (isDebugMode())
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{
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report(DiagnosticsEngine::Fatal,
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"unexpected call to %0 with first argument of non-pointer type %1",
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expr->getExprLoc())
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<< fdecl << e->getType() << expr->getSourceRange();
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report(DiagnosticsEngine::Note, "%0 declared here", fdecl->getLocation())
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<< fdecl << fdecl->getSourceRange();
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}
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return true;
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}
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auto const decl = t->getAsCXXRecordDecl();
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if (decl == nullptr)
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{
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return true;
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}
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if (!decl->isCompleteDefinition())
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{
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return true; // conservatively assume it may be trivial
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}
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if (decl->isTrivial())
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{
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return true;
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}
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report(DiagnosticsEngine::Warning,
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"%0 writing to an object of non-trivial type %1; use assignment instead",
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expr->getExprLoc())
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<< fdecl << decl << expr->getSourceRange();
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return true;
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}
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bool preRun() override { return compiler.getLangOpts().CPlusPlus; }
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private:
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void run() override
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{
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if (preRun())
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{
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TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
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}
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}
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};
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loplugin::Plugin::Registration<ClassMemAccess> classmemaccess("classmemaccess");
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}
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#endif
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/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
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