compilerplugins/clang/mapindex.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9 #ifndef LO_CLANG_SHARED_PLUGINS
  10
  11 #include <memory>
  12 #include <cassert>
  13 #include <string>
  14 #include <iostream>
  15 #include <fstream>
  16 #include <set>
  17
  18 #include "check.hxx"
  19 #include "plugin.hxx"
  20
  21 /**
  22   Look for places we are using map[idx] in a bool context, which allocates an entry in the map, which is sometimes a side-effect we don't want.
  23 */
  24
  25 namespace
  26 {
  27 class MapIndex : public loplugin::FilteringPlugin<MapIndex>
  28 {
  29 public:
  30     explicit MapIndex(loplugin::InstantiationData const& data)
  31         : FilteringPlugin(data)
  32     {
  33     }
  34
  35     virtual void run() override
  36     {
  37         if (preRun())
  38             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  39     }
  40
  41     bool VisitImplicitCastExpr(const ImplicitCastExpr*);
  42     bool VisitMemberExpr(const MemberExpr*);
  43 };
  44
  45 bool MapIndex::VisitMemberExpr(const MemberExpr* memberExpr)
  46 {
  47     if (ignoreLocation(memberExpr))
  48         return true;
  49     // operator bool conversion
  50     auto conversionDecl = dyn_cast<CXXConversionDecl>(memberExpr->getMemberDecl());
  51     if (!conversionDecl || !conversionDecl->getConversionType()->isBooleanType())
  52         return true;
  53     auto operatorCall = dyn_cast<CXXOperatorCallExpr>(memberExpr->getBase()->IgnoreCasts());
  54     if (!operatorCall)
  55         return true;
  56     if (operatorCall->getOperator() != OverloadedOperatorKind::OO_Subscript)
  57         return true;
  58     auto tc = loplugin::TypeCheck(operatorCall->getArg(0)->getType());
  59     if (!tc.Class("map") && !tc.Class("unordered_map"))
  60         return true;
  61     report(DiagnosticsEngine::Warning,
  62            "will create an empty entry in the map, you sure about that, rather use count()1",
  63            operatorCall->getExprLoc());
  64     return true;
  65 }
  66
  67 bool MapIndex::VisitImplicitCastExpr(const ImplicitCastExpr* implicitCastExpr)
  68 {
  69     if (ignoreLocation(implicitCastExpr))
  70     {
  71         return true;
  72     }
  73
  74     // first cast is some kind of "ToBoolean" cast
  75     auto ck = implicitCastExpr->getCastKind();
  76     if (ck != CK_MemberPointerToBoolean && ck != CK_PointerToBoolean && ck != CK_IntegralToBoolean
  77         && ck != CK_FloatingToBoolean && ck != CK_FloatingComplexToBoolean
  78         && ck != CK_IntegralComplexToBoolean)
  79         return true;
  80
  81     // second cast is LValueToRValue
  82     implicitCastExpr = dyn_cast<ImplicitCastExpr>(implicitCastExpr->getSubExpr());
  83     if (!implicitCastExpr)
  84         return true;
  85
  86     if (implicitCastExpr->getCastKind() != CK_LValueToRValue)
  87         return true;
  88     auto operatorCall = dyn_cast<CXXOperatorCallExpr>(implicitCastExpr->getSubExpr());
  89     if (!operatorCall)
  90         return true;
  91     if (operatorCall->getOperator() != OverloadedOperatorKind::OO_Subscript)
  92         return true;
  93     auto tc = loplugin::TypeCheck(operatorCall->getArg(0)->getType());
  94     if (!tc.Class("map") && !tc.Class("unordered_map"))
  95         return true;
  96     report(DiagnosticsEngine::Warning,
  97            "will create an empty entry in the map, you sure about that, rather use count()2",
  98            implicitCastExpr->getExprLoc());
  99     return true;
 100 }
 101
 102 loplugin::Plugin::Registration<MapIndex> mapindex("mapindex");
 103
 104 } // namespace
 105
 106 #endif // LO_CLANG_SHARED_PLUGINS
 107
 108 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */