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