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 #include <cassert>
  11 #include <string>
  12 #include <iostream>
  13 #include <fstream>
  14 #include <set>
  15
  16 #include <clang/AST/CXXInheritance.h>
  17 #include "compat.hxx"
  18 #include "plugin.hxx"
  19
  20 /**
  21 look for unnecessary blocks that just catch and rethrow:
  22     try {
  23        stuff
  24     } catch (exception const &) {
  25       throw;
  26     }
  27 */
  28
  29 namespace {
  30
  31 class UnnecessaryCatchThrow:
  32     public loplugin::FilteringPlugin<UnnecessaryCatchThrow>
  33 {
  34 public:
  35     explicit UnnecessaryCatchThrow(loplugin::InstantiationData const & data): FilteringPlugin(data) {}
  36
  37     virtual void run() override
  38     {
  39         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  40     }
  41
  42     bool VisitCXXTryStmt(CXXTryStmt const *);
  43 };
  44
  45 bool UnnecessaryCatchThrow::VisitCXXTryStmt(CXXTryStmt const * tryStmt)
  46 {
  47     if (ignoreLocation(tryStmt))
  48         return true;
  49     if (tryStmt->getNumHandlers() != 1)
  50         return true;
  51     auto catchStmt = tryStmt->getHandler(0);
  52     auto compoundStmt = dyn_cast<CompoundStmt>(catchStmt->getHandlerBlock());
  53     if (!compoundStmt || compoundStmt->size() != 1)
  54         return true;
  55     auto throwExpr = dyn_cast<CXXThrowExpr>(compoundStmt->body_front());
  56     if (!throwExpr)
  57         return true;
  58     auto subExpr = throwExpr->getSubExpr();
  59     if (subExpr)
  60     {
  61         if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(subExpr)) {
  62             if (!cxxConstructExpr->getConstructor()->isCopyConstructor())
  63                 return true;
  64             if (!cxxConstructExpr->getConstructor()->getParent()->hasAttr<FinalAttr>())
  65                 return true;
  66             if (cxxConstructExpr->getNumArgs() != 1)
  67                 return true;
  68             subExpr = cxxConstructExpr->getArg(0);
  69         }
  70         auto declRefExpr = dyn_cast<DeclRefExpr>(subExpr->IgnoreImpCasts());
  71         if (!declRefExpr)
  72             return true;
  73         if (declRefExpr->getDecl() != catchStmt->getExceptionDecl())
  74             return true;
  75     }
  76
  77     report( DiagnosticsEngine::Warning, "unnecessary catch and throw",
  78             compat::getBeginLoc(catchStmt))
  79             << catchStmt->getSourceRange();
  80     return true;
  81 }
  82
  83
  84 loplugin::Plugin::Registration< UnnecessaryCatchThrow > X("unnecessarycatchthrow");
  85
  86 }
  87
  88 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */