compilerplugins/clang/dynexcspec.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
   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 <algorithm>
  12 #include <functional>
  13
  14 #include "clang/AST/Comment.h"
  15
  16 #include "plugin.hxx"
  17
  18 // Remove dynamic exception specifications.  See the mail thread starting at
  19 // <https://lists.freedesktop.org/archives/libreoffice/2017-January/076665.html>
  20 // "Dynamic Exception Specifications" for details.
  21
  22 namespace {
  23
  24 bool isOverriding(FunctionDecl const * decl) {
  25     if (decl->hasAttr<OverrideAttr>()) {
  26         return true;
  27     }
  28     auto m = dyn_cast<CXXMethodDecl>(decl);
  29     return m != nullptr
  30         && m->begin_overridden_methods() != m->end_overridden_methods();
  31 }
  32
  33 bool isDtorOrDealloc(FunctionDecl const * decl) {
  34     if (isa<CXXDestructorDecl>(decl)) {
  35         return true;
  36     }
  37     switch (decl->getOverloadedOperator()) {
  38     case OO_Delete:
  39     case OO_Array_Delete:
  40         return true;
  41     default:
  42         return false;
  43     }
  44 }
  45
  46 class DynExcSpec:
  47     public loplugin::FilteringRewritePlugin<DynExcSpec>
  48 {
  49 public:
  50     explicit DynExcSpec(loplugin::InstantiationData const & data):
  51         FilteringRewritePlugin(data) {}
  52
  53     bool preRun() override {
  54         return compiler.getLangOpts().CPlusPlus;
  55     }
  56
  57     void run() override {
  58         if (preRun()) {
  59             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  60         }
  61     }
  62
  63     bool VisitFunctionDecl(FunctionDecl const * decl) {
  64         if (ignoreLocation(decl)) {
  65             return true;
  66         }
  67         auto proto = decl->getType()->getAs<FunctionProtoType>();
  68         if (proto == nullptr || proto->getExceptionSpecType() != EST_Dynamic) {
  69             return true;
  70         }
  71         if (decl->isCanonicalDecl() && !isOverriding(decl)
  72             && !anyRedeclHasThrowsDocumentation(decl))
  73         {
  74             report(
  75                 DiagnosticsEngine::Warning,
  76                 ("function declaration has dynamic exception specification but"
  77                  " no corresponding documentation comment"),
  78                 decl->getLocation())
  79                 << decl->getSourceRange();
  80         }
  81         if (rewriter != nullptr) {
  82             if (!(decl->isDefined() || decl->isPure())) {
  83                 return true;
  84             }
  85             if (auto m = dyn_cast<CXXMethodDecl>(decl)) {
  86                 for (auto i = m->begin_overridden_methods();
  87                      i != m->end_overridden_methods(); ++i)
  88                 {
  89                     auto proto2 = (*i)->getType()->getAs<FunctionProtoType>();
  90                     assert(proto2 != nullptr);
  91                     if (proto2->getExceptionSpecType() == EST_Dynamic) {
  92                         return true;
  93                     }
  94                 }
  95             }
  96         }
  97         bool dtorOrDealloc = isDtorOrDealloc(decl);
  98         auto const source = decl->getExceptionSpecSourceRange();
  99         if (rewriter != nullptr && source.isValid()) {
 100             if (dtorOrDealloc) {
 101                 if (replaceText(source, "noexcept(false)")) {
 102                     return true;
 103                 }
 104             } else {
 105                 auto beg = source.getBegin();
 106                 if (beg.isFileID()) {
 107                     for (;;) {
 108                         auto prev = Lexer::GetBeginningOfToken(
 109                             beg.getLocWithOffset(-1),
 110                             compiler.getSourceManager(),
 111                             compiler.getLangOpts());
 112                         auto n = Lexer::MeasureTokenLength(
 113                             prev, compiler.getSourceManager(),
 114                             compiler.getLangOpts());
 115                         auto s = StringRef(
 116                             compiler.getSourceManager().getCharacterData(prev),
 117                             n);
 118                         while (s.startswith("\\\n")) {
 119                             s = s.drop_front(2);
 120                             while (!s.empty()
 121                                    && (s.front() == ' ' || s.front() == '\t'
 122                                        || s.front() == '\n' || s.front() == '\v'
 123                                        || s.front() == '\f'))
 124                             {
 125                                 s = s.drop_front(1);
 126                             }
 127                         }
 128                         if (!s.empty() && s != "\\") {
 129                             if (s.startswith("//")) {
 130                                 beg = source.getBegin();
 131                             }
 132                             break;
 133                         }
 134                         beg = prev;
 135                     }
 136                 }
 137                 if (removeText(SourceRange(beg, source.getEnd()))) {
 138                     return true;
 139                 }
 140             }
 141         }
 142         report(
 143             DiagnosticsEngine::Warning,
 144             (dtorOrDealloc
 145              ? "replace dynamic exception specification with 'noexcept(false)'"
 146              : "remove dynamic exception specification"),
 147             source.isValid() ? source.getBegin() : decl->getLocation())
 148             << (source.isValid() ? source : decl->getSourceRange());
 149         return true;
 150     }
 151
 152 private:
 153     bool hasThrowsDocumentation(FunctionDecl const * decl) {
 154         if (auto cmt = compiler.getASTContext().getCommentForDecl(
 155             decl, &compiler.getPreprocessor()))
 156         {
 157             for (auto i = cmt->child_begin(); i != cmt->child_end(); ++i) {
 158                 if (auto bcc = dyn_cast<comments::BlockCommandComment>(*i)) {
 159                     if (compiler.getASTContext().getCommentCommandTraits()
 160                         .getCommandInfo(bcc->getCommandID())->IsThrowsCommand)
 161                     {
 162                         return true;
 163                     }
 164                 }
 165             }
 166         }
 167         return false;
 168     }
 169
 170     bool anyRedeclHasThrowsDocumentation(FunctionDecl const * decl) {
 171         return std::any_of(
 172             decl->redecls_begin(), decl->redecls_end(),
 173             [this](FunctionDecl * d) { return hasThrowsDocumentation(d); });
 174             // std::bind(
 175             //     &DynExcSpec::hasThrowsDocumentation, this,
 176             //     std::placeholders::_1));
 177     }
 178 };
 179
 180 loplugin::Plugin::Registration<DynExcSpec> dynexcspec("dynexcspec");
 181
 182 } // namespace
 183
 184 #endif // LO_CLANG_SHARED_PLUGINS
 185
 186 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */