compilerplugins/clang/noexceptmove.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 // versions before 9.0 didn't have getExceptionSpecType
  10
  11 #include "check.hxx"
  12 #include "compat.hxx"
  13 #include "plugin.hxx"
  14
  15 #include "config_clang.h"
  16
  17 #include <string>
  18 #include <set>
  19
  20 /**
  21   Look for move constructors that can be noexcept.
  22 */
  23
  24 namespace
  25 {
  26 /// Look for the stuff that can be marked noexcept, but only if we also mark some of the callees noexcept.
  27 /// Off by default so as not too annoy people.
  28 constexpr bool bLookForStuffWeCanFix = false;
  29
  30 class NoExceptMove : public loplugin::FilteringPlugin<NoExceptMove>
  31 {
  32 public:
  33     explicit NoExceptMove(loplugin::InstantiationData const& data)
  34         : FilteringPlugin(data)
  35     {
  36     }
  37
  38     virtual void run() override
  39     {
  40         StringRef fn(handler.getMainFileName());
  41         // ONDXPagePtr::operator= calls ONDXPage::ReleaseRef which cannot be noexcept
  42         if (loplugin::isSamePathname(fn,
  43                                      SRCDIR "/connectivity/source/drivers/dbase/dindexnode.cxx"))
  44             return;
  45         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  46     }
  47
  48     bool shouldVisitImplicitCode() const { return true; }
  49
  50     bool TraverseCXXConstructorDecl(CXXConstructorDecl*);
  51     bool TraverseCXXMethodDecl(CXXMethodDecl*);
  52     bool VisitCallExpr(const CallExpr*);
  53     bool VisitCXXConstructExpr(const CXXConstructExpr*);
  54     bool VisitVarDecl(const VarDecl*);
  55
  56 private:
  57     compat::optional<bool> IsCallThrows(const CallExpr* callExpr);
  58     std::vector<bool> m_ConstructorThrows;
  59     std::vector<std::vector<const Decl*>> m_Exclusions;
  60     std::vector<bool> m_CannotFix;
  61 };
  62
  63 bool NoExceptMove::TraverseCXXConstructorDecl(CXXConstructorDecl* constructorDecl)
  64 {
  65     const bool isMove = constructorDecl->isMoveConstructor()
  66                         && constructorDecl->getExceptionSpecType() == EST_None
  67                         && !constructorDecl->isDefaulted() && !constructorDecl->isDeleted()
  68                         && !ignoreLocation(constructorDecl)
  69                         && constructorDecl->isThisDeclarationADefinition()
  70                         && constructorDecl->getBody() != nullptr;
  71     if (isMove)
  72     {
  73         m_ConstructorThrows.push_back(false);
  74         m_Exclusions.emplace_back();
  75         m_CannotFix.push_back(false);
  76     }
  77     bool rv = RecursiveASTVisitor::TraverseCXXConstructorDecl(constructorDecl);
  78     if (isMove)
  79     {
  80         if (!m_ConstructorThrows.back())
  81         {
  82             report(DiagnosticsEngine::Warning, "move constructor can be noexcept",
  83                    constructorDecl->getSourceRange().getBegin())
  84                 << constructorDecl->getSourceRange();
  85             auto canonicalDecl = constructorDecl->getCanonicalDecl();
  86             if (canonicalDecl != constructorDecl)
  87                 report(DiagnosticsEngine::Note, "declaration here",
  88                        canonicalDecl->getSourceRange().getBegin())
  89                     << canonicalDecl->getSourceRange();
  90         }
  91         else if (bLookForStuffWeCanFix && !m_CannotFix.back())
  92         {
  93             report(DiagnosticsEngine::Warning, "move constructor can be noexcept",
  94                    constructorDecl->getSourceRange().getBegin())
  95                 << constructorDecl->getSourceRange();
  96             auto canonicalDecl = constructorDecl->getCanonicalDecl();
  97             if (canonicalDecl != constructorDecl)
  98                 report(DiagnosticsEngine::Note, "declaration here",
  99                        canonicalDecl->getSourceRange().getBegin())
 100                     << canonicalDecl->getSourceRange();
 101             for (const Decl* callDecl : m_Exclusions.back())
 102                 report(DiagnosticsEngine::Warning, "but need to fix this to be noexcept",
 103                        callDecl->getSourceRange().getBegin())
 104                     << callDecl->getSourceRange();
 105         }
 106         m_ConstructorThrows.pop_back();
 107         m_Exclusions.pop_back();
 108         m_CannotFix.pop_back();
 109     }
 110     return rv;
 111 }
 112
 113 bool NoExceptMove::TraverseCXXMethodDecl(CXXMethodDecl* methodDecl)
 114 {
 115     bool isMove = methodDecl->isMoveAssignmentOperator()
 116                   && methodDecl->getExceptionSpecType() == EST_None && !methodDecl->isDefaulted()
 117                   && !methodDecl->isDeleted() && !ignoreLocation(methodDecl)
 118                   && methodDecl->isThisDeclarationADefinition() && methodDecl->getBody() != nullptr;
 119     if (isMove)
 120     {
 121         StringRef fn = getFilenameOfLocation(
 122             compiler.getSourceManager().getSpellingLoc(methodDecl->getBeginLoc()));
 123         // SfxObjectShellLock::operator= calls SotObject::OwnerLock which in turn calls stuff which cannot be noexcept
 124         if (loplugin::isSamePathname(fn, SRCDIR "/include/sfx2/objsh.hxx"))
 125             isMove = false;
 126     }
 127     if (isMove)
 128     {
 129         m_ConstructorThrows.push_back(false);
 130         m_Exclusions.emplace_back();
 131         m_CannotFix.push_back(false);
 132     }
 133     bool rv = RecursiveASTVisitor::TraverseCXXMethodDecl(methodDecl);
 134     if (isMove)
 135     {
 136         if (!m_ConstructorThrows.back())
 137         {
 138             report(DiagnosticsEngine::Warning, "move operator= can be noexcept",
 139                    methodDecl->getSourceRange().getBegin())
 140                 << methodDecl->getSourceRange();
 141             auto canonicalDecl = methodDecl->getCanonicalDecl();
 142             if (canonicalDecl != methodDecl)
 143                 report(DiagnosticsEngine::Note, "declaration here",
 144                        canonicalDecl->getSourceRange().getBegin())
 145                     << canonicalDecl->getSourceRange();
 146         }
 147         else if (bLookForStuffWeCanFix && !m_CannotFix.back())
 148         {
 149             report(DiagnosticsEngine::Warning, "move operator= can be noexcept",
 150                    methodDecl->getSourceRange().getBegin())
 151                 << methodDecl->getSourceRange();
 152             auto canonicalDecl = methodDecl->getCanonicalDecl();
 153             if (canonicalDecl != methodDecl)
 154                 report(DiagnosticsEngine::Note, "declaration here",
 155                        canonicalDecl->getSourceRange().getBegin())
 156                     << canonicalDecl->getSourceRange();
 157             for (const Decl* callDecl : m_Exclusions.back())
 158                 report(DiagnosticsEngine::Warning, "but need to fix this to be noexcept",
 159                        callDecl->getSourceRange().getBegin())
 160                     << callDecl->getSourceRange();
 161         }
 162         m_ConstructorThrows.pop_back();
 163         m_Exclusions.pop_back();
 164         m_CannotFix.pop_back();
 165     }
 166     return rv;
 167 }
 168
 169 bool NoExceptMove::VisitCallExpr(const CallExpr* callExpr)
 170 {
 171     if (ignoreLocation(callExpr))
 172         return true;
 173     if (m_ConstructorThrows.empty())
 174         return true;
 175     compat::optional<bool> bCallThrows = IsCallThrows(callExpr);
 176     if (!bCallThrows)
 177     {
 178         callExpr->dump();
 179         if (callExpr->getCalleeDecl())
 180             callExpr->getCalleeDecl()->dump();
 181         report(DiagnosticsEngine::Warning, "what's up doc?", callExpr->getSourceRange().getBegin())
 182             << callExpr->getSourceRange();
 183         m_ConstructorThrows.back() = true;
 184         return true;
 185     }
 186     if (*bCallThrows)
 187         m_ConstructorThrows.back() = true;
 188     return true;
 189 }
 190
 191 static bool IsCallThrowsSpec(clang::ExceptionSpecificationType est)
 192 {
 193     return !(est == EST_DynamicNone || est == EST_NoThrow || est == EST_BasicNoexcept
 194              || est == EST_NoexceptTrue);
 195 }
 196
 197 bool NoExceptMove::VisitCXXConstructExpr(const CXXConstructExpr* constructExpr)
 198 {
 199     if (ignoreLocation(constructExpr))
 200         return true;
 201     if (m_ConstructorThrows.empty())
 202         return true;
 203     auto constructorDecl = constructExpr->getConstructor();
 204     auto est = constructorDecl->getExceptionSpecType();
 205     if (constructorDecl->isDefaulted() && est == EST_None)
 206         ; // ok, non-throwing
 207     else if (IsCallThrowsSpec(est))
 208     {
 209         if (bLookForStuffWeCanFix)
 210         {
 211             if (est == EST_None && !ignoreLocation(constructorDecl))
 212                 m_Exclusions.back().push_back(constructorDecl);
 213             else
 214                 m_CannotFix.back() = true;
 215         }
 216         m_ConstructorThrows.back() = true;
 217     }
 218     return true;
 219 }
 220
 221 bool NoExceptMove::VisitVarDecl(const VarDecl* varDecl)
 222 {
 223     if (varDecl->getLocation().isValid() && ignoreLocation(varDecl))
 224         return true;
 225     if (m_ConstructorThrows.empty())
 226         return true;
 227     // The clang AST does not show me implicit calls to destructors at the end of a block,
 228     // so assume any local var decls of class type will call their destructor.
 229     if (!varDecl->getType()->isRecordType())
 230         return true;
 231     auto cxxRecordDecl = varDecl->getType()->getAsCXXRecordDecl();
 232     if (!cxxRecordDecl)
 233         return true;
 234     auto destructorDecl = cxxRecordDecl->getDestructor();
 235     if (!destructorDecl)
 236         return true;
 237     auto est = destructorDecl->getExceptionSpecType();
 238     if (destructorDecl->isDefaulted() && est == EST_None)
 239         ; // ok, non-throwing
 240     else if (IsCallThrowsSpec(est))
 241     {
 242         if (bLookForStuffWeCanFix)
 243         {
 244             if (est == EST_None && !ignoreLocation(destructorDecl))
 245                 m_Exclusions.back().push_back(destructorDecl);
 246             else
 247                 m_CannotFix.back() = true;
 248         }
 249         m_ConstructorThrows.back() = true;
 250     }
 251     return true;
 252 }
 253
 254 compat::optional<bool> NoExceptMove::IsCallThrows(const CallExpr* callExpr)
 255 {
 256     const FunctionDecl* calleeFunctionDecl = callExpr->getDirectCallee();
 257     if (calleeFunctionDecl)
 258     {
 259         auto est = calleeFunctionDecl->getExceptionSpecType();
 260         if (bLookForStuffWeCanFix)
 261         {
 262             if (est == EST_None && !ignoreLocation(calleeFunctionDecl))
 263                 m_Exclusions.back().push_back(calleeFunctionDecl);
 264             else
 265                 m_CannotFix.back() = true;
 266         }
 267         // Allowlist of functions that could be noexcept, but we can't change them because of backwards-compatibility reasons
 268         // css::uno::XInterface::acquire
 269         // css::uno::XInterface::release
 270         if (calleeFunctionDecl->getIdentifier())
 271         {
 272             auto name = calleeFunctionDecl->getName();
 273             if (auto cxxMethodDecl = dyn_cast<CXXMethodDecl>(calleeFunctionDecl))
 274                 if (loplugin::ContextCheck(cxxMethodDecl->getParent()->getDeclContext())
 275                         .Namespace("uno")
 276                         .Namespace("star")
 277                         .Namespace("sun")
 278                         .Namespace("com")
 279                         .GlobalNamespace()
 280                     && (name == "acquire" || name == "release"))
 281                     return false;
 282             if (name == "osl_releasePipe" || name == "osl_destroySocketAddr")
 283                 return false;
 284         }
 285         return IsCallThrowsSpec(est);
 286     }
 287
 288     auto calleeExpr = callExpr->getCallee();
 289     if (isa<CXXDependentScopeMemberExpr>(calleeExpr) || isa<UnresolvedLookupExpr>(calleeExpr))
 290     {
 291         m_CannotFix.back() = true;
 292         return true;
 293     }
 294
 295     // check for call via function-pointer
 296     clang::QualType calleeType;
 297     if (auto fieldDecl = dyn_cast_or_null<FieldDecl>(callExpr->getCalleeDecl()))
 298         calleeType = fieldDecl->getType();
 299     else if (auto varDecl = dyn_cast_or_null<VarDecl>(callExpr->getCalleeDecl()))
 300         calleeType = varDecl->getType();
 301     else
 302     {
 303         m_CannotFix.back() = true;
 304         return compat::optional<bool>();
 305     }
 306
 307     // allowlist of functions that could be noexcept, but we can't change them because of backwards-compatibility reasons
 308     if (auto typedefType = calleeType->getAs<TypedefType>())
 309         if (typedefType->getDecl()->getName() == "uno_ReleaseMappingFunc")
 310             return false;
 311
 312     if (calleeType->isPointerType())
 313         calleeType = calleeType->getPointeeType();
 314     auto funcProto = calleeType->getAs<FunctionProtoType>();
 315     if (!funcProto)
 316     {
 317         m_CannotFix.back() = true;
 318         return compat::optional<bool>();
 319     }
 320
 321     auto est = funcProto->getExceptionSpecType();
 322     if (bLookForStuffWeCanFix)
 323     {
 324         m_CannotFix.back() = true; // TODO, could improve
 325     }
 326     return IsCallThrowsSpec(est);
 327 }
 328
 329 loplugin::Plugin::Registration<NoExceptMove> noexceptmove("noexceptmove");
 330 }
 331
 332 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */