123 lines
4.1 KiB
C++
123 lines
4.1 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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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 <string>
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#include <set>
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#include <iostream>
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#include <fstream>
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#include "plugin.hxx"
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#include "compat.hxx"
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#include "check.hxx"
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/**
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Look for & and operator& expressions where the result is always zero.
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Generally a mistake when people meant to use | or operator|
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*/
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namespace {
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static bool startswith(const std::string& rStr, const char* pSubStr) {
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return rStr.compare(0, strlen(pSubStr), pSubStr) == 0;
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}
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class ExpressionAlwaysZero:
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public RecursiveASTVisitor<ExpressionAlwaysZero>, public loplugin::Plugin
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{
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public:
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explicit ExpressionAlwaysZero(loplugin::InstantiationData const & data): Plugin(data) {}
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virtual void run() override
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{
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std::string fn( compiler.getSourceManager().getFileEntryForID(
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compiler.getSourceManager().getMainFileID())->getName() );
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loplugin::normalizeDotDotInFilePath(fn);
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// encoding of constant value for binary file format
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if (startswith(fn, SRCDIR "/package/source/zipapi/ZipFile.cxx"))
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return;
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TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
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}
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bool VisitBinaryOperator(BinaryOperator const *);
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bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr const *);
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bool TraverseStaticAssertDecl(StaticAssertDecl *);
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private:
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// note, abusing std::unique_ptr as a std::optional lookalike
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std::unique_ptr<APSInt> getExprValue(const Expr* arg);
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};
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bool ExpressionAlwaysZero::VisitBinaryOperator( BinaryOperator const * binaryOperator )
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{
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if (ignoreLocation(binaryOperator))
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return true;
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if (binaryOperator->getLocStart().isMacroID())
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return true;
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if (binaryOperator->getOpcode() != BO_And)
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return true;
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auto lhsValue = getExprValue(binaryOperator->getLHS());
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auto rhsValue = getExprValue(binaryOperator->getRHS());
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if (!lhsValue || !rhsValue || (lhsValue->getExtValue() & rhsValue->getExtValue()) != 0)
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return true;
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report(
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DiagnosticsEngine::Warning, "expression always evaluates to zero, lhs=%0 rhs=%1",
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binaryOperator->getLocStart())
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<< lhsValue->toString(10)
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<< rhsValue->toString(10)
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<< binaryOperator->getSourceRange();
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return true;
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}
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bool ExpressionAlwaysZero::VisitCXXOperatorCallExpr( CXXOperatorCallExpr const * cxxOperatorCallExpr )
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{
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if (ignoreLocation(cxxOperatorCallExpr))
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return true;
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if (cxxOperatorCallExpr->getLocStart().isMacroID())
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return true;
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if (cxxOperatorCallExpr->getOperator() != clang::OverloadedOperatorKind::OO_Amp)
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return true;
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if (cxxOperatorCallExpr->getNumArgs() != 2)
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return true;
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auto lhsValue = getExprValue(cxxOperatorCallExpr->getArg(0));
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auto rhsValue = getExprValue(cxxOperatorCallExpr->getArg(1));
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if (!lhsValue || !rhsValue || (lhsValue->getExtValue() & rhsValue->getExtValue()) != 0)
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return true;
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report(
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DiagnosticsEngine::Warning, "expression always evaluates to zero, lhs=%0 rhs=%1",
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cxxOperatorCallExpr->getLocStart())
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<< lhsValue->toString(10)
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<< rhsValue->toString(10)
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<< cxxOperatorCallExpr->getSourceRange();
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return true;
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}
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std::unique_ptr<APSInt> ExpressionAlwaysZero::getExprValue(Expr const * expr)
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{
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expr = expr->IgnoreParenCasts();
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// ignore this, it seems to trigger an infinite recursion
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if (isa<UnaryExprOrTypeTraitExpr>(expr)) {
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return std::unique_ptr<APSInt>();
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}
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APSInt x1;
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if (expr->EvaluateAsInt(x1, compiler.getASTContext()))
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return std::unique_ptr<APSInt>(new APSInt(x1));
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return std::unique_ptr<APSInt>();
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}
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// these will often evaluate to zero harmlessly
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bool ExpressionAlwaysZero::TraverseStaticAssertDecl( StaticAssertDecl * )
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{
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return true;
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}
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loplugin::Plugin::Registration< ExpressionAlwaysZero > X("expressionalwayszero");
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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