compilerplugins/clang/rangedforcopy.cxx

   1
   2 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   3 /*
   4  * This file is part of the LibreOffice project.
   5  *
   6  * This Source Code Form is subject to the terms of the Mozilla Public
   7  * License, v. 2.0. If a copy of the MPL was not distributed with this
   8  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   9  */
  10 #ifndef LO_CLANG_SHARED_PLUGINS
  11
  12 #include <string>
  13 #include <iostream>
  14
  15 #include "plugin.hxx"
  16 #include "clang/AST/CXXInheritance.h"
  17
  18 // Check that we're not unnecessarily copying variables in a range based for loop
  19 // e.g. "for (OUString a: aList)" results in a copy of each string being made,
  20 // whereas "for (const OUString& a: aList)" does not.
  21
  22 namespace
  23 {
  24
  25 class RangedForCopy:
  26     public loplugin::FilteringPlugin<RangedForCopy>
  27 {
  28 public:
  29     explicit RangedForCopy(loplugin::InstantiationData const & data):
  30         FilteringPlugin(data) {}
  31
  32     virtual void run() override {
  33         if (preRun())
  34             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  35     }
  36
  37     bool VisitCXXForRangeStmt( const CXXForRangeStmt* stmt );
  38 };
  39
  40 bool RangedForCopy::VisitCXXForRangeStmt( const CXXForRangeStmt* stmt )
  41 {
  42     if (ignoreLocation( stmt ))
  43         return true;
  44
  45     const VarDecl* varDecl = stmt->getLoopVariable();
  46     if (!varDecl)
  47       return true;
  48
  49     const QualType type = varDecl->getType();
  50     if (type->isRecordType() && !type->isReferenceType() && !type->isPointerType())
  51     {
  52         std::string name = type.getAsString();
  53         report(
  54                DiagnosticsEngine::Warning,
  55                "Loop variable passed by value, pass by reference instead, e.g. 'const %0&'",
  56                compat::getBeginLoc(varDecl))
  57                << name << varDecl->getSourceRange();
  58     }
  59
  60     return true;
  61 }
  62
  63
  64 loplugin::Plugin::Registration< RangedForCopy > rangedforcopy("rangedforcopy");
  65
  66 } // namespace
  67
  68 #endif // LO_CLANG_SHARED_PLUGINS
  69
  70 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */