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