compilerplugins/clang/sequenceloop.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   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 #ifndef LO_CLANG_SHARED_PLUGINS
  10
  11 #include <cassert>
  12 #include <string>
  13 #include <iostream>
  14 #include <fstream>
  15 #include <set>
  16
  17 #include <clang/AST/CXXInheritance.h>
  18 #include "plugin.hxx"
  19 #include "check.hxx"
  20
  21 /**
  22   When used in "for" loops, css::uno::Sequence objects tend to end up calling the non-const begin()/end(),
  23   which is considerably more expensive than the const variants because it forces a local copy
  24   of the internal ref-counted impl object.
  25 */
  26
  27 namespace
  28 {
  29 class SequenceLoop : public loplugin::FilteringPlugin<SequenceLoop>
  30 {
  31 public:
  32     explicit SequenceLoop(loplugin::InstantiationData const& data)
  33         : FilteringPlugin(data)
  34     {
  35     }
  36
  37     virtual void run() override
  38     {
  39         if (preRun())
  40             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  41     }
  42
  43     bool VisitCXXForRangeStmt(CXXForRangeStmt const*);
  44 };
  45
  46 bool SequenceLoop::VisitCXXForRangeStmt(CXXForRangeStmt const* forStmt)
  47 {
  48     if (ignoreLocation(forStmt))
  49         return true;
  50
  51     auto tc = loplugin::TypeCheck(forStmt->getRangeInit()->getType());
  52     if (tc.Const())
  53         return true;
  54     if (!tc.Class("Sequence")
  55              .Namespace("uno")
  56              .Namespace("star")
  57              .Namespace("sun")
  58              .Namespace("com")
  59              .GlobalNamespace())
  60         return true;
  61     const VarDecl* varDecl = forStmt->getLoopVariable();
  62     auto tc2 = loplugin::TypeCheck(varDecl->getType());
  63     if (!tc2.LvalueReference().Const())
  64         return true;
  65
  66     report(DiagnosticsEngine::Warning,
  67            ("use std::as_const, or otherwise make the for-range-initializer expression const, to"
  68             " avoid creating a copy of the Sequence"),
  69            compat::getBeginLoc(forStmt->getRangeInit()))
  70         << forStmt->getSourceRange();
  71     return true;
  72 }
  73
  74 loplugin::Plugin::Registration<SequenceLoop> sequenceloop("sequenceloop");
  75
  76 } // namespace
  77
  78 #endif // LO_CLANG_SHARED_PLUGINS
  79
  80 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */