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
  11 #include <string>
  12 #include <iostream>
  13
  14 #include "plugin.hxx"
  15 #include "clang/AST/CXXInheritance.h"
  16
  17 // Check that we're not unnecessarily copying variables in a range based for loop
  18 // e.g. "for (OUString a: aList)" results in a copy of each string being made,
  19 // whereas "for (const OUString& a: aList)" does not.
  20
  21 namespace
  22 {
  23
  24 class RangedForCopy:
  25     public loplugin::FilteringPlugin<RangedForCopy>
  26 {
  27 public:
  28     explicit RangedForCopy(loplugin::InstantiationData const & data):
  29         FilteringPlugin(data) {}
  30
  31     virtual void run() override {
  32         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  33     }
  34
  35     bool VisitCXXForRangeStmt( const CXXForRangeStmt* stmt );
  36 };
  37
  38 bool RangedForCopy::VisitCXXForRangeStmt( const CXXForRangeStmt* stmt )
  39 {
  40     if (ignoreLocation( stmt ))
  41         return true;
  42
  43     const VarDecl* varDecl = stmt->getLoopVariable();
  44     if (!varDecl)
  45       return true;
  46
  47     const QualType type = varDecl->getType();
  48     if (type->isRecordType() && !type->isReferenceType() && !type->isPointerType())
  49     {
  50         std::string name = type.getAsString();
  51         report(
  52                DiagnosticsEngine::Warning,
  53                "Loop variable passed by value, pass by reference instead, e.g. 'const %0&'",
  54                compat::getBeginLoc(varDecl))
  55                << name << varDecl->getSourceRange();
  56     }
  57
  58     return true;
  59 }
  60
  61
  62 loplugin::Plugin::Registration< RangedForCopy > X("rangedforcopy");
  63
  64 }
  65
  66 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */