105 lines
3.3 KiB
C++
105 lines
3.3 KiB
C++
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/* -*- 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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#include "check.hxx"
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#include "plugin.hxx"
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// Find variable declarations at namespace scope that need not have external
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// linkage.
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namespace {
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// It looks like Clang wrongly implements DR 4
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// (<http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#4>) and treats
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// a variable declared in an 'extern "..." {...}'-style linkage-specification as
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// if it contained the 'extern' specifier:
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bool hasExternalLinkage(VarDecl const * decl) {
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if (decl->getLinkageAndVisibility().getLinkage() != ExternalLinkage) {
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return false;
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}
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for (auto ctx = decl->getLexicalDeclContext();
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ctx->getDeclKind() != Decl::TranslationUnit;
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ctx = ctx->getLexicalParent())
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{
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if (auto ls = dyn_cast<LinkageSpecDecl>(ctx)) {
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if (!ls->hasBraces()) {
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return true;
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}
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if (auto prev = decl->getPreviousDecl()) {
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return hasExternalLinkage(prev);
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}
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return !decl->isInAnonymousNamespace();
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}
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}
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return true;
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}
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class ExternVar: public RecursiveASTVisitor<ExternVar>, public loplugin::Plugin
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{
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public:
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explicit ExternVar(InstantiationData const & data): Plugin(data) {}
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void run() override
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{ TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
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bool VisitVarDecl(VarDecl const * decl) {
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if (ignoreLocation(decl)) {
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return true;
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}
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if (decl->isStaticDataMember()) {
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return true;
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}
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if (!(decl->isFirstDecl()
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&& compiler.getSourceManager().isInMainFile(decl->getLocation())
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&& hasExternalLinkage(decl)))
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{
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return true;
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}
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auto def = decl->getDefinition();
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if (def == nullptr) {
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// Code like
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//
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// namespace { extern int v; }
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// int f() { return sizeof(v); }
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//
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// is already handled by Clang itself with an error "variable 'v' is
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// not needed and will not be emitted"
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return true;
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}
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report(
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DiagnosticsEngine::Warning,
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"variable with external linkage not declared in an include file",
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def->getLocation())
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<< def->getSourceRange();
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report(
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DiagnosticsEngine::Note,
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("should either have internal linkage or be declared in an include"
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" file"),
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def->getLocation())
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<< def->getSourceRange();
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for (auto prev = def;;) {
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prev = prev->getPreviousDecl();
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if (prev == nullptr) {
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break;
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}
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report(
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DiagnosticsEngine::Note, "previously declared here",
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prev->getLocation())
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<< prev->getSourceRange();
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}
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return true;
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}
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};
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loplugin::Plugin::Registration<ExternVar> X("externvar");
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
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