compilerplugins/clang/doubleconvert.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
   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
  10 #include "check.hxx"
  11 #include "compat.hxx"
  12 #include "plugin.hxx"
  13
  14 /**
  15  * Look for places where we are converting from type A through a conversion operator and back to type A,
  16  * which is redundant. At the moment only look for Color, to aid my ColorData->Color conversion
  17  */
  18 namespace
  19 {
  20 class DoubleConvert final : public RecursiveASTVisitor<DoubleConvert>, public loplugin::Plugin
  21 {
  22 public:
  23     explicit DoubleConvert(loplugin::InstantiationData const& data)
  24         : Plugin(data)
  25     {
  26     }
  27     void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
  28
  29     bool VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr const*);
  30 };
  31
  32 /**
  33  The AST looks like:
  34
  35  CXXOperatorCallExpr 0x8e5b840 'class Color' lvalue
  36 |-ImplicitCastExpr 0x8e5b828 'class Color &(*)(class Color &&) noexcept' <FunctionToPointerDecay>
  37 | `-DeclRefExpr 0x8e5b800 'class Color &(class Color &&) noexcept' lvalue CXXMethod 0x8e59a08 'operator=' 'class Color &(class Color &&) noexcept'
  38 |-DeclRefExpr 0x8e5b678 'class Color' lvalue Var 0x8e5b5d0 'col2' 'class Color'
  39 `-MaterializeTemporaryExpr 0x8e5b7e8 'class Color' xvalue
  40   `-CXXConstructExpr 0x8e5b7b0 'class Color' 'void (ColorData)'
  41     `-ImplicitCastExpr 0x8e5b798 'ColorData':'unsigned int' <IntegralCast>
  42       `-CXXFunctionalCastExpr 0x8e5b770 'sal_Int32':'int' functional cast to sal_Int32 <NoOp>
  43         `-ImplicitCastExpr 0x8e5b758 'sal_Int32':'int' <UserDefinedConversion>
  44           `-CXXMemberCallExpr 0x8e5b730 'sal_Int32':'int'
  45             `-MemberExpr 0x8e5b6f8 '<bound member function type>' .operator int 0x8e51048
  46               `-ImplicitCastExpr 0x8e5b6e0 'const class Color' lvalue <NoOp>
  47                 `-DeclRefExpr 0x8e5b6b0 'class Color' lvalue Var 0x8e5b518 'col1' 'class Color'
  48 */
  49 bool DoubleConvert::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr const* materializetemp)
  50 {
  51     if (ignoreLocation(materializetemp))
  52         return true;
  53     auto cxxConstruct
  54         = dyn_cast<CXXConstructExpr>(materializetemp->GetTemporaryExpr()->IgnoreParenCasts());
  55     if (!cxxConstruct)
  56         return true;
  57     if (cxxConstruct->getNumArgs() == 0)
  58         return true;
  59     auto cxxMemberCallExpr
  60         = dyn_cast<CXXMemberCallExpr>(cxxConstruct->getArg(0)->IgnoreParenCasts());
  61     if (!cxxMemberCallExpr)
  62         return true;
  63     if (!isa<CXXConversionDecl>(cxxMemberCallExpr->getMethodDecl()))
  64         return true;
  65     if (materializetemp->getType().getCanonicalType().getTypePtr()
  66         != cxxMemberCallExpr->getImplicitObjectArgument()
  67                ->getType()
  68                .getCanonicalType()
  69                .getTypePtr())
  70         return true;
  71     if (!loplugin::TypeCheck(materializetemp->getType().getCanonicalType())
  72              .Class("Color")
  73              .GlobalNamespace())
  74         return true;
  75
  76     report(DiagnosticsEngine::Warning, "redundant double conversion", materializetemp->getExprLoc())
  77         << materializetemp->getSourceRange();
  78     return true;
  79 }
  80
  81 static loplugin::Plugin::Registration<DoubleConvert> reg("doubleconvert");
  82 }
  83
  84 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */