[PATCH] D31697: Check for null before using TUScope

[Kim Gräsman via Phabricator via cfe-commits]

kimgr added a comment.

For some context, the backtrace when this happens is:

         include-what-you-use.exe!clang::Scope::getEntity() Line 313	C++
  	include-what-you-use.exe!clang::Sema::PushOnScopeChains(clang::NamedDecl * D=0x07ed05b0, clang::Scope * S=0x00000000, bool AddToContext=true) Line 1302	C++
  	include-what-you-use.exe!clang::Sema::LazilyCreateBuiltin(clang::IdentifierInfo * II=0x008087f0, unsigned int ID=0x00000114, clang::Scope * S=0x00000000, bool ForRedeclaration=false, clang::SourceLocation Loc={...}) Line 1910	C++
  	include-what-you-use.exe!LookupBuiltin(clang::Sema & S={...}, clang::LookupResult & R={...}) Line 699	C++
  	include-what-you-use.exe!LookupDirect(clang::Sema & S={...}, clang::LookupResult & R={...}, const clang::DeclContext * DC=0x007c1a14) Line 850	C++
  	include-what-you-use.exe!CppNamespaceLookup(clang::Sema & S={...}, clang::LookupResult & R={...}, clang::ASTContext & Context={...}, clang::DeclContext * NS=0x007c1a14, `anonymous-namespace'::UnqualUsingDirectiveSet & UDirs={...}) Line 931	C++
  	include-what-you-use.exe!clang::Sema::CppLookupName(clang::LookupResult & R={...}, clang::Scope * S=0x0078c870) Line 1310	C++
  	include-what-you-use.exe!clang::Sema::LookupName(clang::LookupResult & R={...}, clang::Scope * S=0x079fcd10, bool AllowBuiltinCreation=false) Line 1798	C++
  	include-what-you-use.exe!clang::Sema::getTypeName(const clang::IdentifierInfo & II={...}, clang::SourceLocation NameLoc={...}, clang::Scope * S=0x079fcd10, clang::CXXScopeSpec * SS=0x0449db94, bool isClassName=false, bool HasTrailingDot=false, clang::OpaquePtr<clang::QualType> ObjectTypePtr={...}, bool IsCtorOrDtorName=false, bool WantNontrivialTypeSourceInfo=true, bool IsClassTemplateDeductionContext=true, clang::IdentifierInfo * * CorrectedII=0x00000000) Line 331	C++
  	include-what-you-use.exe!clang::Parser::TryAnnotateTypeOrScopeTokenAfterScopeSpec(clang::CXXScopeSpec & SS={...}, bool IsNewScope=true) Line 1727	C++
  	include-what-you-use.exe!clang::Parser::TryAnnotateTypeOrScopeToken() Line 1717	C++
  	include-what-you-use.exe!clang::Parser::ParseCastExpression(bool isUnaryExpression=false, bool isAddressOfOperand=false, bool & NotCastExpr=false, clang::Parser::TypeCastState isTypeCast=NotTypeCast, bool isVectorLiteral=false) Line 876	C++
  	include-what-you-use.exe!clang::Parser::ParseCastExpression(bool isUnaryExpression=false, bool isAddressOfOperand=false, clang::Parser::TypeCastState isTypeCast=NotTypeCast, bool isVectorLiteral=false) Line 484	C++
  	include-what-you-use.exe!clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState isTypeCast=NotTypeCast) Line 171	C++
  	include-what-you-use.exe!clang::Parser::ParseExpression(clang::Parser::TypeCastState isTypeCast=NotTypeCast) Line 121	C++
  	include-what-you-use.exe!clang::Parser::ParseReturnStatement() Line 1905	C++
  	include-what-you-use.exe!clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt *,32> & Stmts={...}, clang::Parser::AllowedConstructsKind Allowed=ACK_Any, clang::SourceLocation * TrailingElseLoc=0x00000000, clang::Parser::ParsedAttributesWithRange & Attrs={...}) Line 265	C++
  	include-what-you-use.exe!clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt *,32> & Stmts={...}, clang::Parser::AllowedConstructsKind Allowed=ACK_Any, clang::SourceLocation * TrailingElseLoc=0x00000000) Line 113	C++
  	include-what-you-use.exe!clang::Parser::ParseCompoundStatementBody(bool isStmtExpr=false) Line 996	C++
  	include-what-you-use.exe!clang::Parser::ParseFunctionStatementBody(clang::Decl * Decl=0x07e84ce0, clang::Parser::ParseScope & BodyScope={...}) Line 1965	C++
  	include-what-you-use.exe!clang::Parser::ParseLateTemplatedFuncDef(clang::LateParsedTemplate & LPT={...}) Line 1418	C++
  	include-what-you-use.exe!clang::Parser::LateTemplateParserCallback(void * P=0x0077d438, clang::LateParsedTemplate & LPT={...}) Line 1339	C++
  	include-what-you-use.exe!include_what_you_use::IwyuAstConsumer::ParseFunctionTemplates(clang::TranslationUnitDecl * decl=0x007c1a00) Line 3558	C++
  	include-what-you-use.exe!include_what_you_use::IwyuAstConsumer::HandleTranslationUnit(clang::ASTContext & context={...}) Line 3503	C++
  	include-what-you-use.exe!clang::ParseAST(clang::Sema & S={...}, bool PrintStats=false, bool SkipFunctionBodies=false) Line 159	C++
  	include-what-you-use.exe!clang::ASTFrontendAction::ExecuteAction() Line 611	C++
  	include-what-you-use.exe!clang::FrontendAction::Execute() Line 512	C++
  	include-what-you-use.exe!clang::CompilerInstance::ExecuteAction(clang::FrontendAction & Act={...}) Line 970	C++

This is triggered when we invoke a hacky hook in Sema to force instantiation of late-parsed function templates:

  void ParseFunctionTemplates(TranslationUnitDecl* decl) {
    set<FunctionDecl*> late_parsed_decls = GetLateParsedFunctionDecls(decl);
    clang::Sema& sema = compiler()->getSema();
  
    // If we have any late-parsed functions, make sure the
    // -fdelayed-template-parsing flag is on. Otherwise we don't know where
    // they came from.
    CHECK_((compiler()->getLangOpts().DelayedTemplateParsing ||
            late_parsed_decls.empty()) &&
           "Should not have late-parsed decls without "
           "-fdelayed-template-parsing.");
  
    for (const FunctionDecl* fd : late_parsed_decls) {
      CHECK_(fd->isLateTemplateParsed());
  
      if (CanIgnoreLocation(GetLocation(fd)))
        continue;
  
      // Force parsing and AST building of the yet-uninstantiated function
      // template body.
      clang::LateParsedTemplate* lpt = sema.LateParsedTemplateMap[fd].get();
      sema.LateTemplateParser(sema.OpaqueParser, *lpt);
    }
  }

That `LateTemplateParser` call is a little crazy, of course, but it's the only way as far as I know to force-instantiate under `-fdelayed-template-parsing`.

Maybe this gives some context to judge whether the null-check is the right fix for the crash.


https://reviews.llvm.org/D31697