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