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