compilerplugins/clang/unnecessarycatchthrow.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
  18 #include <clang/AST/CXXInheritance.h>
  19 #include "plugin.hxx"
  20
  21 /**
  22 look for unnecessary blocks that just catch and rethrow:
  23     try {
  24        stuff
  25     } catch (exception const &) {
  26       throw;
  27     }
  28 */
  29
  30 namespace {
  31
  32 class UnnecessaryCatchThrow:
  33     public loplugin::FilteringPlugin<UnnecessaryCatchThrow>
  34 {
  35 public:
  36     explicit UnnecessaryCatchThrow(loplugin::InstantiationData const & data): FilteringPlugin(data) {}
  37
  38     virtual void run() override
  39     {
  40         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  41     }
  42
  43     bool VisitCXXTryStmt(CXXTryStmt const *);
  44 };
  45
  46 bool UnnecessaryCatchThrow::VisitCXXTryStmt(CXXTryStmt const * tryStmt)
  47 {
  48     if (ignoreLocation(tryStmt))
  49         return true;
  50     if (tryStmt->getNumHandlers() != 1)
  51         return true;
  52     auto catchStmt = tryStmt->getHandler(0);
  53     auto compoundStmt = dyn_cast<CompoundStmt>(catchStmt->getHandlerBlock());
  54     if (!compoundStmt || compoundStmt->size() != 1)
  55         return true;
  56     auto throwExpr = dyn_cast<CXXThrowExpr>(compoundStmt->body_front());
  57     if (!throwExpr)
  58         return true;
  59     auto subExpr = throwExpr->getSubExpr();
  60     if (subExpr)
  61     {
  62         if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(subExpr)) {
  63             if (!cxxConstructExpr->getConstructor()->isCopyConstructor())
  64                 return true;
  65             if (!cxxConstructExpr->getConstructor()->getParent()->hasAttr<FinalAttr>())
  66                 return true;
  67             if (cxxConstructExpr->getNumArgs() != 1)
  68                 return true;
  69             subExpr = cxxConstructExpr->getArg(0);
  70         }
  71         auto declRefExpr = dyn_cast<DeclRefExpr>(subExpr->IgnoreImpCasts());
  72         if (!declRefExpr)
  73             return true;
  74         if (declRefExpr->getDecl() != catchStmt->getExceptionDecl())
  75             return true;
  76     }
  77
  78     report( DiagnosticsEngine::Warning, "unnecessary catch and throw",
  79             catchStmt->getBeginLoc())
  80             << catchStmt->getSourceRange();
  81     return true;
  82 }
  83
  84
  85 loplugin::Plugin::Registration< UnnecessaryCatchThrow > unnecessarycatchthrow("unnecessarycatchthrow");
  86
  87 } // namespace
  88
  89 #endif // LO_CLANG_SHARED_PLUGINS
  90
  91 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */