compilerplugins/clang/emptyif.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
  10 #ifndef LO_CLANG_SHARED_PLUGINS
  11
  12 #include <cassert>
  13 #include <string>
  14 #include <iostream>
  15 #include <fstream>
  16 #include <set>
  17 #include "plugin.hxx"
  18
  19 /**
  20   Check for places where we do
  21    if (xxx) ;
  22   or
  23    if (xxx) {}
  24  */
  25 namespace
  26 {
  27 class EmptyIf : public loplugin::FilteringRewritePlugin<EmptyIf>
  28 {
  29 public:
  30     explicit EmptyIf(loplugin::InstantiationData const& data)
  31         : FilteringRewritePlugin(data)
  32     {
  33     }
  34
  35     virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
  36
  37     bool VisitIfStmt(IfStmt const*);
  38
  39 private:
  40     bool ContainsComment(Stmt const*);
  41 };
  42
  43 static bool empty(Stmt const* stmt)
  44 {
  45     if (isa<NullStmt>(stmt))
  46         return true;
  47     auto compoundStmt = dyn_cast<CompoundStmt>(stmt);
  48     if (!compoundStmt)
  49         return false;
  50     return compoundStmt->size() == 0;
  51 }
  52
  53 bool EmptyIf::ContainsComment(Stmt const* stmt)
  54 {
  55     auto range = stmt->getSourceRange();
  56     SourceManager& SM = compiler.getSourceManager();
  57     SourceLocation startLoc = range.getBegin();
  58     SourceLocation endLoc = range.getEnd();
  59     char const* p1 = SM.getCharacterData(startLoc);
  60     char const* p2 = SM.getCharacterData(endLoc);
  61     p2 += Lexer::MeasureTokenLength(endLoc, SM, compiler.getLangOpts());
  62     auto s = llvm::StringRef(p1, p2 - p1);
  63     return s.find("//") != llvm::StringRef::npos || s.find("/*") != llvm::StringRef::npos
  64            || s.find("#if") != llvm::StringRef::npos;
  65 }
  66
  67 bool EmptyIf::VisitIfStmt(IfStmt const* ifStmt)
  68 {
  69     if (ignoreLocation(ifStmt))
  70         return true;
  71
  72     if (ifStmt->getElse() && empty(ifStmt->getElse()) && !ContainsComment(ifStmt->getElse()))
  73     {
  74         report(DiagnosticsEngine::Warning, "empty else body", ifStmt->getElse()->getBeginLoc())
  75             << ifStmt->getElse()->getSourceRange();
  76         return true;
  77     }
  78
  79     if (!ifStmt->getElse() && empty(ifStmt->getThen()) && !ContainsComment(ifStmt->getThen()))
  80     {
  81         report(DiagnosticsEngine::Warning, "empty if body", ifStmt->getBeginLoc())
  82             << ifStmt->getSourceRange();
  83     }
  84
  85     return true;
  86 }
  87
  88 loplugin::Plugin::Registration<EmptyIf> emptyif("emptyif", true);
  89 }
  90
  91 #endif // LO_CLANG_SHARED_PLUGINS
  92
  93 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */