[Parser] Avoid spurious 'missing template' error in presence of typos

[hokein]

Summary

Suppress those diagnostics if lhs of a member expression contains
errors. Typo correction produces dependent expressions even in
non-template code, that led to spurious diagnostics before.

Also includes a small refactoring to improve code calling
ParseUnqualifiedId and ParseOptionalCXXScopeSpecifier in the common case
when ObjectType is null. This allows to avoid boiler plate required to
propagate whether lhs of a member expression had any errors in the
common code path.

previous:

/tmp/t.cpp:6:17: error: use 'template' keyword to treat 'f' as a dependent template name
auto a = bilder.f<int>();
                ^
                template
/tmp/t.cpp:6:10: error: use of undeclared identifier 'bilder'; did you mean 'builder'?
auto a = bilder.f<int>();
         ^~~~~~
         builder

vs now:

/tmp/t.cpp:6:10: error: use of undeclared identifier 'bilder'; did you mean 'builder'?
auto a = bilder.f<int>();
         ^~~~~~
         builder

[hokein]

• rebase to master
• update some comments

[hokein]

remove an accident change.

[hokein]

rebase to master.

[sammccall]

Nice!

I don't love adding those overloads, but not clear there's something better.

clang/lib/Parse/ParseExprCXX.cpp

2973

I'd consider inlining these convenience overloads

clang/lib/Parse/ParseTemplate.cpp

685

nit: ObjectHadErrors=

685

this can use the simple overload, ParsedType() is the same as nullptr

[hokein]

address review comments, remove the overload.

clang/include/clang/Parse/Parser.h

private:
 
   bool areTokensAdjacent(const Token &A, const Token &B);
 
   void CheckForTemplateAndDigraph(Token &Next, ParsedType ObjectTypePtr,
                                   bool EnteringContext, IdentifierInfo &II,
                                   CXXScopeSpec &SS);
 
   bool ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS, ParsedType ObjectType,
+                                      bool ObjectHasErrors,
+                                      bool EnteringContext,
+                                      bool *MayBePseudoDestructor = nullptr,
+                                      bool IsTypename = false,
+                                      IdentifierInfo **LastII = nullptr,
+                                      bool OnlyNamespace = false,
+                                      bool InUsingDeclaration = false);
+  /// An overload for the common case of non-member expressions, i.e. when
+  /// ObjectType is null.
+  bool ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
                                       bool EnteringContext,
                                       bool *MayBePseudoDestructor = nullptr,
                                       bool IsTypename = false,
                                       IdentifierInfo **LastII = nullptr,
                                       bool OnlyNamespace = false,
                                       bool InUsingDeclaration = false);
 
   //===--------------------------------------------------------------------===//
private:
 
   //===--------------------------------------------------------------------===//
   //  C++ : Microsoft __uuidof Expression
   ExprResult ParseCXXUuidof();
 
   //===--------------------------------------------------------------------===//
   // C++ 5.2.4: C++ Pseudo-Destructor Expressions
   ExprResult ParseCXXPseudoDestructor(Expr *Base, SourceLocation OpLoc,
-                                            tok::TokenKind OpKind,
-                                            CXXScopeSpec &SS,
-                                            ParsedType ObjectType);
+                                      tok::TokenKind OpKind, CXXScopeSpec &SS,
 
   //===--------------------------------------------------------------------===//
   // C++ 9.3.2: C++ 'this' pointer
   ExprResult ParseCXXThis();
 
   //===--------------------------------------------------------------------===//
   // C++ 15: C++ Throw Expression
   ExprResult ParseThrowExpression();
private:
   //===--------------------------------------------------------------------===//
   // C++ 10: Derived classes [class.derived]
   TypeResult ParseBaseTypeSpecifier(SourceLocation &BaseLoc,
                                     SourceLocation &EndLocation);
   void ParseBaseClause(Decl *ClassDecl);
   BaseResult ParseBaseSpecifier(Decl *ClassDecl);
   AccessSpecifier getAccessSpecifierIfPresent() const;
 
-  bool ParseUnqualifiedIdTemplateId(CXXScopeSpec &SS,
+  bool ParseUnqualifiedIdTemplateId(CXXScopeSpec &SS, ParsedType ObjectType,
+                                    bool ObjectHadErrors,
                                     SourceLocation TemplateKWLoc,
                                     IdentifierInfo *Name,
                                     SourceLocation NameLoc,
-                                    bool EnteringContext,
-                                    ParsedType ObjectType,
-                                    UnqualifiedId &Id,
+                                    bool EnteringContext, UnqualifiedId &Id,
                                     bool AssumeTemplateId);
   bool ParseUnqualifiedIdOperator(CXXScopeSpec &SS, bool EnteringContext,
                                   ParsedType ObjectType,
                                   UnqualifiedId &Result);
 
   //===--------------------------------------------------------------------===//
   // OpenMP: Directives and clauses.
   /// Parse clauses for '#pragma omp declare simd'.
struct OpenMPVarListDataTy {
     bool IsMapTypeImplicit = false;
     SourceLocation DepLinMapLastLoc;
   };
 
   /// Parses clauses with list.
   bool ParseOpenMPVarList(OpenMPDirectiveKind DKind, OpenMPClauseKind Kind,
                           SmallVectorImpl<Expr *> &Vars,
                           OpenMPVarListDataTy &Data);
+  bool ParseUnqualifiedId(CXXScopeSpec &SS, ParsedType ObjectType,
+                          bool ObjectHadErrors, bool EnteringContext,
+                          bool AllowDestructorName, bool AllowConstructorName,
+                          bool AllowDeductionGuide,
+                          SourceLocation *TemplateKWLoc, UnqualifiedId &Result);
+  /// A convenient overload for the common case of non-member expressions,
+  /// i.e. when ObjectType is null.
   bool ParseUnqualifiedId(CXXScopeSpec &SS, bool EnteringContext,
-                          bool AllowDestructorName,
-                          bool AllowConstructorName,
+                          bool AllowDestructorName, bool AllowConstructorName,
                           bool AllowDeductionGuide,
-                          ParsedType ObjectType,
-                          SourceLocation *TemplateKWLoc,
-                          UnqualifiedId &Result);
+                          SourceLocation *TemplateKWLoc, UnqualifiedId &Result);
   /// Parses the mapper modifier in map, to, and from clauses.
   bool parseMapperModifier(OpenMPVarListDataTy &Data);
   /// Parses map-type-modifiers in map clause.
   /// map([ [map-type-modifier[,] [map-type-modifier[,] ...] map-type : ] list)
   /// where, map-type-modifier ::= always | close | mapper(mapper-identifier)
   bool parseMapTypeModifiers(OpenMPVarListDataTy &Data);
 
 private:

clang/include/clang/Sema/Sema.h

enum class AssumedTemplateKind {
     FoundFunctions,
   };
   bool LookupTemplateName(LookupResult &R, Scope *S, CXXScopeSpec &SS,
                           QualType ObjectType, bool EnteringContext,
                           bool &MemberOfUnknownSpecialization,
                           SourceLocation TemplateKWLoc = SourceLocation(),
                           AssumedTemplateKind *ATK = nullptr);
 
-  TemplateNameKind isTemplateName(Scope *S,
-                                  CXXScopeSpec &SS,
+  TemplateNameKind isTemplateName(Scope *S, CXXScopeSpec &SS,
                                   bool hasTemplateKeyword,
                                   const UnqualifiedId &Name,
-                                  ParsedType ObjectType,
-                                  bool EnteringContext,
+                                  ParsedType ObjectType, bool EnteringContext,
                                   TemplateTy &Template,
                                   bool &MemberOfUnknownSpecialization);
 
   /// Try to resolve an undeclared template name as a type template.
   ///
   /// Sets II to the identifier corresponding to the template name, and updates
   /// Name to a corresponding (typo-corrected) type template name and TNK to
   /// the corresponding kind, if possible.

clang/lib/Parse/ParseDecl.cpp

void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
 
   CXXScopeSpec &SS = DS.getTypeSpecScope();
   if (getLangOpts().CPlusPlus) {
     // "enum foo : bar;" is not a potential typo for "enum foo::bar;"
     // if a fixed underlying type is allowed.
     ColonProtectionRAIIObject X(*this, AllowDeclaration);
 
     CXXScopeSpec Spec;
-    if (ParseOptionalCXXScopeSpecifier(Spec, nullptr,
-                                       /*EnteringContext=*/true))
+    if (ParseOptionalCXXScopeSpecifier(Spec, /*EnteringContext=*/true))
       return;
 
     if (Spec.isSet() && Tok.isNot(tok::identifier)) {
       Diag(Tok, diag::err_expected) << tok::identifier;
       if (Tok.isNot(tok::l_brace)) {
         // Has no name and is not a definition.
         // Skip the rest of this declarator, up until the comma or semicolon.
         SkipUntil(tok::comma, StopAtSemi);
#include "clang/Basic/OpenCLImageTypes.def"
   }
 }
 
 bool Parser::isConstructorDeclarator(bool IsUnqualified, bool DeductionGuide) {
   TentativeParsingAction TPA(*this);
 
   // Parse the C++ scope specifier.
   CXXScopeSpec SS;
-  if (ParseOptionalCXXScopeSpecifier(SS, nullptr,
-                                     /*EnteringContext=*/true)) {
+  if (ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/true)) {
     TPA.Revert();
     return false;
   }
 
   // Parse the constructor name.
   if (Tok.is(tok::identifier)) {
     // We already know that we have a constructor name; just consume
     // the token.
if (getLangOpts().CPlusPlus &&
       (Tok.is(tok::coloncolon) || Tok.is(tok::kw_decltype) ||
        (Tok.is(tok::identifier) &&
         (NextToken().is(tok::coloncolon) || NextToken().is(tok::less))) ||
        Tok.is(tok::annot_cxxscope))) {
     bool EnteringContext =
         D.getContext() == DeclaratorContext::FileContext ||
         D.getContext() == DeclaratorContext::MemberContext;
     CXXScopeSpec SS;
-    ParseOptionalCXXScopeSpecifier(SS, nullptr, EnteringContext);
+    ParseOptionalCXXScopeSpecifier(SS, EnteringContext);
 
     if (SS.isNotEmpty()) {
       if (Tok.isNot(tok::star)) {
         // The scope spec really belongs to the direct-declarator.
         if (D.mayHaveIdentifier())
           D.getCXXScopeSpec() = SS;
         else
           AnnotateScopeToken(SS, true);
ColonProtectionRAIIObject X(
                    (D.getContext() == DeclaratorContext::ForContext &&
                     getLangOpts().CPlusPlus11));
 
     // ParseDeclaratorInternal might already have parsed the scope.
     if (D.getCXXScopeSpec().isEmpty()) {
       bool EnteringContext =
           D.getContext() == DeclaratorContext::FileContext ||
           D.getContext() == DeclaratorContext::MemberContext;
-      ParseOptionalCXXScopeSpecifier(D.getCXXScopeSpec(), nullptr,
-                                     EnteringContext);
+      ParseOptionalCXXScopeSpecifier(D.getCXXScopeSpec(), EnteringContext);
     }
 
     if (D.getCXXScopeSpec().isValid()) {
       if (Actions.ShouldEnterDeclaratorScope(getCurScope(),
                                              D.getCXXScopeSpec()))
         // Change the declaration context for name lookup, until this function
         // is exited (and the declarator has been parsed).
         DeclScopeObj.EnterDeclaratorScope();
if (Tok.isOneOf(tok::identifier, tok::kw_operator, tok::annot_template_id,
           (D.getContext() == DeclaratorContext::FileContext ||
            D.getContext() == DeclaratorContext::MemberContext);
       }
 
       bool HadScope = D.getCXXScopeSpec().isValid();
       if (ParseUnqualifiedId(D.getCXXScopeSpec(),
                              /*EnteringContext=*/true,
                              /*AllowDestructorName=*/true, AllowConstructorName,
-                             AllowDeductionGuide, nullptr, nullptr,
-                             D.getName()) ||
+                             AllowDeductionGuide, nullptr, D.getName()) ||
           // Once we're past the identifier, if the scope was bad, mark the
           // whole declarator bad.
           D.getCXXScopeSpec().isInvalid()) {
         D.SetIdentifier(nullptr, Tok.getLocation());
         D.setInvalidType(true);
       } else {
         // ParseUnqualifiedId might have parsed a scope specifier during error
         // recovery. If it did so, enter that scope.

clang/lib/Parse/ParseDeclCXX.cpp

Decl *Parser::ParseNamespaceAlias(SourceLocation NamespaceLoc,
   if (Tok.is(tok::code_completion)) {
     Actions.CodeCompleteNamespaceAliasDecl(getCurScope());
     cutOffParsing();
     return nullptr;
   }
 
   CXXScopeSpec SS;
   // Parse (optional) nested-name-specifier.
-  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false,
+  ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false,
                                  /*MayBePseudoDestructor=*/nullptr,
                                  /*IsTypename=*/false,
                                  /*LastII=*/nullptr,
                                  /*OnlyNamespace=*/true);
 
   if (Tok.isNot(tok::identifier)) {
     Diag(Tok, diag::err_expected_namespace_name);
     // Skip to end of the definition and eat the ';'.
Decl *Parser::ParseUsingDirective(DeclaratorContext Context,
   if (Tok.is(tok::code_completion)) {
     Actions.CodeCompleteUsingDirective(getCurScope());
     cutOffParsing();
     return nullptr;
   }
 
   CXXScopeSpec SS;
   // Parse (optional) nested-name-specifier.
-  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false,
+  ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false,
                                  /*MayBePseudoDestructor=*/nullptr,
                                  /*IsTypename=*/false,
                                  /*LastII=*/nullptr,
                                  /*OnlyNamespace=*/true);
 
   IdentifierInfo *NamespcName = nullptr;
   SourceLocation IdentLoc = SourceLocation();
 
bool Parser::ParseUsingDeclarator(DeclaratorContext Context,
 
   if (Tok.is(tok::kw___super)) {
     Diag(Tok.getLocation(), diag::err_super_in_using_declaration);
     return true;
   }
 
   // Parse nested-name-specifier.
   IdentifierInfo *LastII = nullptr;
-  if (ParseOptionalCXXScopeSpecifier(D.SS, nullptr, /*EnteringContext=*/false,
+  if (ParseOptionalCXXScopeSpecifier(D.SS, /*EnteringContext=*/false,
                                      /*MayBePseudoDtor=*/nullptr,
                                      /*IsTypename=*/false,
                                      /*LastII=*/&LastII,
                                      /*OnlyNamespace=*/false,
                                      /*InUsingDeclaration=*/true))
 
     return true;
   if (D.SS.isInvalid())
if (getLangOpts().CPlusPlus11 &&
     SourceLocation IdLoc = ConsumeToken();
     ParsedType Type =
         Actions.getInheritingConstructorName(D.SS, IdLoc, *LastII);
     D.Name.setConstructorName(Type, IdLoc, IdLoc);
   } else {
     if (ParseUnqualifiedId(
             D.SS, /*EnteringContext=*/false,
             /*AllowDestructorName=*/true,
-            /*AllowConstructorName=*/!(Tok.is(tok::identifier) &&
-                                       NextToken().is(tok::equal)),
-            /*AllowDeductionGuide=*/false,
-            nullptr, nullptr, D.Name))
+            /*AllowConstructorName=*/
+            !(Tok.is(tok::identifier) && NextToken().is(tok::equal)),
+            /*AllowDeductionGuide=*/false, nullptr, D.Name))
       return true;
   }
 
   if (TryConsumeToken(tok::ellipsis, D.EllipsisLoc))
     Diag(Tok.getLocation(), getLangOpts().CPlusPlus17 ?
          diag::warn_cxx17_compat_using_declaration_pack :
          diag::ext_using_declaration_pack);
 
TypeResult Parser::ParseBaseTypeSpecifier(SourceLocation &BaseLoc,
   if (Tok.is(tok::kw_typename)) {
     Diag(Tok, diag::err_expected_class_name_not_template)
       << FixItHint::CreateRemoval(Tok.getLocation());
     ConsumeToken();
   }
 
   // Parse optional nested-name-specifier
   CXXScopeSpec SS;
-  if (ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false))
+  if (ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false))
     return true;
 
   BaseLoc = Tok.getLocation();
 
   // Parse decltype-specifier
   // tok == kw_decltype is just error recovery, it can only happen when SS
   // isn't empty
   if (Tok.isOneOf(tok::kw_decltype, tok::annot_decltype)) {
void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   CXXScopeSpec &SS = DS.getTypeSpecScope();
   if (getLangOpts().CPlusPlus) {
     // "FOO : BAR" is not a potential typo for "FOO::BAR".  In this context it
     // is a base-specifier-list.
     ColonProtectionRAIIObject X(*this);
 
     CXXScopeSpec Spec;
     bool HasValidSpec = true;
-    if (ParseOptionalCXXScopeSpecifier(Spec, nullptr, EnteringContext)) {
+    if (ParseOptionalCXXScopeSpecifier(Spec, EnteringContext)) {
       DS.SetTypeSpecError();
       HasValidSpec = false;
     }
     if (Spec.isSet())
       if (Tok.isNot(tok::identifier) && Tok.isNot(tok::annot_template_id)) {
         Diag(Tok, diag::err_expected) << tok::identifier;
         HasValidSpec = false;
       }
if (!TemplateInfo.Kind &&
     else if (NextToken().is(tok::identifier))
       isAccessDecl = GetLookAheadToken(2).is(tok::semi);
     else
       isAccessDecl = NextToken().is(tok::kw_operator);
 
     if (isAccessDecl) {
       // Collect the scope specifier token we annotated earlier.
       CXXScopeSpec SS;
-      ParseOptionalCXXScopeSpecifier(SS, nullptr,
-                                     /*EnteringContext=*/false);
+      ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false);
 
       if (SS.isInvalid()) {
         SkipUntil(tok::semi);
         return nullptr;
       }
 
       // Try to parse an unqualified-id.
       SourceLocation TemplateKWLoc;
       UnqualifiedId Name;
-      if (ParseUnqualifiedId(SS, false, true, true, false, nullptr,
-                             &TemplateKWLoc, Name)) {
+      if (ParseUnqualifiedId(SS, false, true, true, false, &TemplateKWLoc,
+                             Name)) {
         SkipUntil(tok::semi);
         return nullptr;
       }
 
       // TODO: recover from mistakenly-qualified operator declarations.
       if (ExpectAndConsume(tok::semi, diag::err_expected_after,
                            "access declaration")) {
         SkipUntil(tok::semi);

 /// [C++0x] mem-initializer-id braced-init-list
 ///
 /// [C++] mem-initializer-id:
 ///         '::'[opt] nested-name-specifier[opt] class-name
 ///         identifier
 MemInitResult Parser::ParseMemInitializer(Decl *ConstructorDecl) {
   // parse '::'[opt] nested-name-specifier[opt]
   CXXScopeSpec SS;
-  if (ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false))
+  if (ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false))
     return true;
 
   // : identifier
   IdentifierInfo *II = nullptr;
   SourceLocation IdLoc = Tok.getLocation();
   // : declype(...)
   DeclSpec DS(AttrFactory);
   // : template_name<...>

clang/lib/Parse/ParseExpr.cpp

case tok::annot_cxxscope: { // [C++] id-expression: qualified-id
     Token Next = NextToken();
     if (Next.is(tok::annot_template_id)) {
       TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Next);
       if (TemplateId->Kind == TNK_Type_template) {
         // We have a qualified template-id that we know refers to a
         // type, translate it into a type and continue parsing as a
         // cast expression.
         CXXScopeSpec SS;
-        ParseOptionalCXXScopeSpecifier(SS, nullptr,
-                                       /*EnteringContext=*/false);
+        ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false);
         AnnotateTemplateIdTokenAsType(SS);
         return ParseCastExpression(ParseKind, isAddressOfOperand, NotCastExpr,
                                    isTypeCast, isVectorLiteral,
                                    NotPrimaryExpression);
       }
     }
 
     // Parse as an id-expression.
case tok::period: {
         }
 
         LHS = Actions.ActOnStartCXXMemberReference(getCurScope(), Base,
                                                    OpLoc, OpKind, ObjectType,
                                                    MayBePseudoDestructor);
         if (LHS.isInvalid())
           break;
 
-        ParseOptionalCXXScopeSpecifier(SS, ObjectType,
-                                       /*EnteringContext=*/false,
-                                       &MayBePseudoDestructor);
+        ParseOptionalCXXScopeSpecifier(
+            SS, ObjectType, LHS.get() && LHS.get()->containsErrors(),
+            /*EnteringContext=*/false, &MayBePseudoDestructor);
         if (SS.isNotEmpty())
           ObjectType = nullptr;
       }
 
       if (Tok.is(tok::code_completion)) {
         tok::TokenKind CorrectedOpKind =
             OpKind == tok::arrow ? tok::period : tok::arrow;
         ExprResult CorrectedLHS(/*Invalid=*/true);
case tok::period: {
         //   'class' as if it were an identifier.
         //
         // This hack allows property access to the 'class' method because it is
         // such a common method name. For other C++ keywords that are
         // Objective-C method names, one must use the message send syntax.
         IdentifierInfo *Id = Tok.getIdentifierInfo();
         SourceLocation Loc = ConsumeToken();
         Name.setIdentifier(Id, Loc);
-      } else if (ParseUnqualifiedId(SS,
-                                    /*EnteringContext=*/false,
-                                    /*AllowDestructorName=*/true,
-                                    /*AllowConstructorName=*/
-                                    getLangOpts().MicrosoftExt &&
-                                        SS.isNotEmpty(),
-                                    /*AllowDeductionGuide=*/false,
-                                    ObjectType, &TemplateKWLoc, Name)) {
+      } else if (ParseUnqualifiedId(
+                     SS, ObjectType, LHS.get() && LHS.get()->containsErrors(),
+                     getLangOpts().MicrosoftExt && SS.isNotEmpty(),
+                     /*AllowDeductionGuide=*/false, &TemplateKWLoc, Name)) {
         (void)Actions.CorrectDelayedTyposInExpr(LHS);
         LHS = ExprError();
       }
 
       if (!LHS.isInvalid())
         LHS = Actions.ActOnMemberAccessExpr(getCurScope(), LHS.get(), OpLoc,
                                             OpKind, SS, TemplateKWLoc, Name,
                                  CurParsedObjCImpl ? CurParsedObjCImpl->Dcl

clang/lib/Parse/ParseExprCXX.cpp

 ///
 /// \param SS the scope specifier that will be set to the parsed
 /// nested-name-specifier (or empty)
 ///
 /// \param ObjectType if this nested-name-specifier is being parsed following
 /// the "." or "->" of a member access expression, this parameter provides the
 /// type of the object whose members are being accessed.
 ///
+/// \param ObjectHadErrors if this unqualified-id occurs within a member access
+/// expression, indicates whether the original subexpressions had any errors.
+/// When true, diagnostics for missing 'template' keyword will be supressed.
+///
 /// \param EnteringContext whether we will be entering into the context of
 /// the nested-name-specifier after parsing it.
 ///
 /// \param MayBePseudoDestructor When non-NULL, points to a flag that
 /// indicates whether this nested-name-specifier may be part of a
 /// pseudo-destructor name. In this case, the flag will be set false
 /// if we don't actually end up parsing a destructor name. Moreorover,
 /// if we do end up determining that we are parsing a destructor name,
 /// the last component of the nested-name-specifier is not parsed as
 /// part of the scope specifier.
 ///
 /// \param IsTypename If \c true, this nested-name-specifier is known to be
 /// part of a type name. This is used to improve error recovery.
 ///
 /// \param LastII When non-NULL, points to an IdentifierInfo* that will be
 /// filled in with the leading identifier in the last component of the
 /// nested-name-specifier, if any.
 ///
 /// \param OnlyNamespace If true, only considers namespaces in lookup.
 ///
 ///
 /// \returns true if there was an error parsing a scope specifier
-bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
-                                            ParsedType ObjectType,
-                                            bool EnteringContext,
-                                            bool *MayBePseudoDestructor,
-                                            bool IsTypename,
-                                            IdentifierInfo **LastII,
-                                            bool OnlyNamespace,
-                                            bool InUsingDeclaration) {
+bool Parser::ParseOptionalCXXScopeSpecifier(
+    CXXScopeSpec &SS, ParsedType ObjectType, bool ObjectHadErrors,
+    bool EnteringContext, bool *MayBePseudoDestructor, bool IsTypename,
+    IdentifierInfo **LastII, bool OnlyNamespace, bool InUsingDeclaration) {
   assert(getLangOpts().CPlusPlus &&
          "Call sites of this function should be guarded by checking for C++");
 
   if (Tok.is(tok::annot_cxxscope)) {
     assert(!LastII && "want last identifier but have already annotated scope");
     assert(!MayBePseudoDestructor && "unexpected annot_cxxscope");
     Actions.RestoreNestedNameSpecifierAnnotation(Tok.getAnnotationValue(),
                                                  Tok.getAnnotationRange(),
if (Next.is(tok::less)) {
         if (AnnotateTemplateIdToken(Template, TNK, SS, SourceLocation(),
                                     TemplateName, false))
           return true;
         continue;
       }
 
       if (MemberOfUnknownSpecialization && (ObjectType || SS.isSet()) &&
           (IsTypename || isTemplateArgumentList(1) == TPResult::True)) {
+        // If we had errors before, ObjectType can be dependent even without any
+        // templates, do not report missing template keyword in that case.
+        if (!ObjectHadErrors) {
           // We have something like t::getAs<T>, where getAs is a
           // member of an unknown specialization. However, this will only
           // parse correctly as a template, so suggest the keyword 'template'
           // before 'getAs' and treat this as a dependent template name.
           unsigned DiagID = diag::err_missing_dependent_template_keyword;
           if (getLangOpts().MicrosoftExt)
             DiagID = diag::warn_missing_dependent_template_keyword;
 
           Diag(Tok.getLocation(), DiagID)
               << II.getName()
               << FixItHint::CreateInsertion(Tok.getLocation(), "template ");
+        }
 
         if (TemplateNameKind TNK = Actions.ActOnDependentTemplateName(
                 getCurScope(), SS, Tok.getLocation(), TemplateName, ObjectType,
                 EnteringContext, Template, /*AllowInjectedClassName*/ true)) {
           // Consume the identifier.
           ConsumeToken();
           if (AnnotateTemplateIdToken(Template, TNK, SS, SourceLocation(),
                                       TemplateName, false))
bool Parser::ParseOptionalCXXScopeSpecifier(
   // still check whether there is a tilde in this position, which
   // indicates a potential pseudo-destructor.
   if (CheckForDestructor && !HasScopeSpecifier && Tok.is(tok::tilde))
     *MayBePseudoDestructor = true;
 
   return false;
 }
 
+bool Parser::ParseOptionalCXXScopeSpecifier(
+    CXXScopeSpec &SS, bool EnteringContext, bool *MayBePseudoDestructor,
+    bool IsTypename, IdentifierInfo **LastII, bool OnlyNamespace,
+    bool IsUsingDeclaration) {
+  return ParseOptionalCXXScopeSpecifier(
+      SS, /*ObjectType=*/nullptr,
+      /*ObjectHadErrors=*/false, EnteringContext, MayBePseudoDestructor,
+      IsTypename, LastII, OnlyNamespace, IsUsingDeclaration);
+}
+
 ExprResult Parser::tryParseCXXIdExpression(CXXScopeSpec &SS,
                                            bool isAddressOfOperand,
                                            Token &Replacement) {
   ExprResult E;
 
   // We may have already annotated this id-expression.
   switch (Tok.getKind()) {
   case tok::annot_non_type: {
ExprResult Parser::tryParseCXXIdExpression(CXXScopeSpec &SS,
 
   default:
     SourceLocation TemplateKWLoc;
     UnqualifiedId Name;
     if (ParseUnqualifiedId(SS,
                            /*EnteringContext=*/false,
                            /*AllowDestructorName=*/false,
                            /*AllowConstructorName=*/false,
-                           /*AllowDeductionGuide=*/false,
-                           /*ObjectType=*/nullptr, &TemplateKWLoc, Name))
+                           /*AllowDeductionGuide=*/false, &TemplateKWLoc, Name))
       return ExprError();
 
     // This is only the direct operand of an & operator if it is not
     // followed by a postfix-expression suffix.
     if (isAddressOfOperand && isPostfixExpressionSuffixStart())
       isAddressOfOperand = false;
 
     E = Actions.ActOnIdExpression(

 /// appear.
 ///
 ExprResult Parser::ParseCXXIdExpression(bool isAddressOfOperand) {
   // qualified-id:
   //   '::'[opt] nested-name-specifier 'template'[opt] unqualified-id
   //   '::' unqualified-id
   //
   CXXScopeSpec SS;
-  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false);
+  ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false);
 
   Token Replacement;
   ExprResult Result =
       tryParseCXXIdExpression(SS, isAddressOfOperand, Replacement);
   if (Result.isUnset()) {
     // If the ExprResult is valid but null, then typo correction suggested a
     // keyword replacement that needs to be reparsed.
     UnconsumeToken(Replacement);
Parser::ParseCXXPseudoDestructor(Expr *Base, SourceLocation OpLoc,
   UnqualifiedId SecondTypeName;
   IdentifierInfo *Name = Tok.getIdentifierInfo();
   SourceLocation NameLoc = ConsumeToken();
   SecondTypeName.setIdentifier(Name, NameLoc);
 
   // If there is a '<', the second type name is a template-id. Parse
   // it as such.
   if (Tok.is(tok::less) &&
-      ParseUnqualifiedIdTemplateId(SS, SourceLocation(),
-                                   Name, NameLoc,
-                                   false, ObjectType, SecondTypeName,
-                                   /*AssumeTemplateId=*/true))
+      ParseUnqualifiedIdTemplateId(
+          SS, ObjectType, Base && Base->containsErrors(), SourceLocation(),
+          Name, NameLoc, false, SecondTypeName,
     return ExprError();
 
   return Actions.ActOnPseudoDestructorExpr(getCurScope(), Base, OpLoc, OpKind,
                                            SS, FirstTypeName, CCLoc, TildeLoc,
                                            SecondTypeName);
 }
 
 /// ParseCXXBoolLiteral - This handles the C++ Boolean literals.

 /// operator-function-id is parsed by \c ParseUnqualifiedId() to determine
 /// whether the unqualified-id is actually a template-id. This routine will
 /// then parse the template arguments and form the appropriate template-id to
 /// return to the caller.
 ///
 /// \param SS the nested-name-specifier that precedes this template-id, if
 /// we're actually parsing a qualified-id.
 ///
+/// \param ObjectType if this unqualified-id occurs within a member access
+/// expression, the type of the base object whose member is being accessed.
+///
+/// \param ObjectHadErrors this unqualified-id occurs within a member access
+/// expression, indicates whether the original subexpressions had any errors.
+///
 /// \param Name for constructor and destructor names, this is the actual
 /// identifier that may be a template-name.
 ///
 /// \param NameLoc the location of the class-name in a constructor or
 /// destructor.
 ///
 /// \param EnteringContext whether we're entering the scope of the
 /// nested-name-specifier.
 ///
-/// \param ObjectType if this unqualified-id occurs within a member access
-/// expression, the type of the base object whose member is being accessed.
-///
 /// \param Id as input, describes the template-name or operator-function-id
 /// that precedes the '<'. If template arguments were parsed successfully,
 /// will be updated with the template-id.
 ///
 /// \param AssumeTemplateId When true, this routine will assume that the name
 /// refers to a template without performing name lookup to verify.
 ///
 /// \returns true if a parse error occurred, false otherwise.
-bool Parser::ParseUnqualifiedIdTemplateId(CXXScopeSpec &SS,
-                                          SourceLocation TemplateKWLoc,
-                                          IdentifierInfo *Name,
-                                          SourceLocation NameLoc,
-                                          bool EnteringContext,
-                                          ParsedType ObjectType,
-                                          UnqualifiedId &Id,
-                                          bool AssumeTemplateId) {
+bool Parser::ParseUnqualifiedIdTemplateId(
+    CXXScopeSpec &SS, ParsedType ObjectType, bool ObjectHadErrors,
+    SourceLocation TemplateKWLoc, IdentifierInfo *Name, SourceLocation NameLoc,
+    bool EnteringContext, UnqualifiedId &Id, bool AssumeTemplateId) {
   assert(Tok.is(tok::less) && "Expected '<' to finish parsing a template-id");
 
   TemplateTy Template;
   TemplateNameKind TNK = TNK_Non_template;
   switch (Id.getKind()) {
   case UnqualifiedIdKind::IK_Identifier:
   case UnqualifiedIdKind::IK_OperatorFunctionId:
   case UnqualifiedIdKind::IK_LiteralOperatorId:
if (AssumeTemplateId) {
       // name, double-check that makes sense syntactically before committing
       // to it.
       if (TNK == TNK_Undeclared_template &&
           isTemplateArgumentList(0) == TPResult::False)
         return false;
 
       if (TNK == TNK_Non_template && MemberOfUnknownSpecialization &&
           ObjectType && isTemplateArgumentList(0) == TPResult::True) {
+        // If we had errors before, ObjectType can be dependent even without any
+        // templates, do not report missing template keyword in that case.
+        if (!ObjectHadErrors) {
           // We have something like t->getAs<T>(), where getAs is a
           // member of an unknown specialization. However, this will only
           // parse correctly as a template, so suggest the keyword 'template'
           // before 'getAs' and treat this as a dependent template name.
           std::string Name;
           if (Id.getKind() == UnqualifiedIdKind::IK_Identifier)
             Name = std::string(Id.Identifier->getName());
           else {
             Name = "operator ";
             if (Id.getKind() == UnqualifiedIdKind::IK_OperatorFunctionId)
               Name += getOperatorSpelling(Id.OperatorFunctionId.Operator);
             else
               Name += Id.Identifier->getName();
           }
           Diag(Id.StartLocation, diag::err_missing_dependent_template_keyword)
               << Name
               << FixItHint::CreateInsertion(Id.StartLocation, "template ");
+        }
         TNK = Actions.ActOnDependentTemplateName(
             getCurScope(), SS, TemplateKWLoc, Id, ObjectType, EnteringContext,
             Template, /*AllowInjectedClassName*/ true);
         if (TNK == TNK_Non_template)
           return true;
       }
     }
     break;

 ///         ~ class-name
 ///         template-id
 ///
 /// \endcode
 ///
 /// \param SS The nested-name-specifier that preceded this unqualified-id. If
 /// non-empty, then we are parsing the unqualified-id of a qualified-id.
 ///
+/// \param ObjectType if this unqualified-id occurs within a member access
+/// expression, the type of the base object whose member is being accessed.
+///
+/// \param ObjectHadErrors if this unqualified-id occurs within a member access
+/// expression, indicates whether the original subexpressions had any errors.
+/// When true, diagnostics for missing 'template' keyword will be supressed.
+///
 /// \param EnteringContext whether we are entering the scope of the
 /// nested-name-specifier.
 ///
 /// \param AllowDestructorName whether we allow parsing of a destructor name.
 ///
 /// \param AllowConstructorName whether we allow parsing a constructor name.
 ///
 /// \param AllowDeductionGuide whether we allow parsing a deduction guide name.
 ///
-/// \param ObjectType if this unqualified-id occurs within a member access
-/// expression, the type of the base object whose member is being accessed.
-///
 /// \param Result on a successful parse, contains the parsed unqualified-id.
 ///
 /// \returns true if parsing fails, false otherwise.
-bool Parser::ParseUnqualifiedId(CXXScopeSpec &SS, bool EnteringContext,
+bool Parser::ParseUnqualifiedId(CXXScopeSpec &SS, ParsedType ObjectType,
+                                bool ObjectHadErrors, bool EnteringContext,
                                 bool AllowDestructorName,
                                 bool AllowConstructorName,
                                 bool AllowDeductionGuide,
-                                ParsedType ObjectType,
                                 SourceLocation *TemplateKWLoc,
                                 UnqualifiedId &Result) {
   if (TemplateKWLoc)
     *TemplateKWLoc = SourceLocation();
 
   // Handle 'A::template B'. This is for template-ids which have not
   // already been annotated by ParseOptionalCXXScopeSpecifier().
   bool TemplateSpecified = false;
if (AllowConstructorName &&
       // We have parsed an identifier.
       Result.setIdentifier(Id, IdLoc);
     }
 
     // If the next token is a '<', we may have a template.
     TemplateTy Template;
     if (Tok.is(tok::less))
       return ParseUnqualifiedIdTemplateId(
-          SS, TemplateKWLoc ? *TemplateKWLoc : SourceLocation(), Id, IdLoc,
-          EnteringContext, ObjectType, Result, TemplateSpecified);
+          SS, ObjectType, ObjectHadErrors,
+          TemplateKWLoc ? *TemplateKWLoc : SourceLocation(), Id, IdLoc,
+          EnteringContext, Result, TemplateSpecified);
     else if (TemplateSpecified &&
              Actions.ActOnDependentTemplateName(
                  getCurScope(), SS, *TemplateKWLoc, Result, ObjectType,
                  EnteringContext, Template,
                  /*AllowInjectedClassName*/ true) == TNK_Non_template)
       return true;
 
     return false;
if (Tok.is(tok::kw_operator)) {
     //
     //   template-id:
     //     operator-function-id < template-argument-list[opt] >
     TemplateTy Template;
     if ((Result.getKind() == UnqualifiedIdKind::IK_OperatorFunctionId ||
          Result.getKind() == UnqualifiedIdKind::IK_LiteralOperatorId) &&
         Tok.is(tok::less))
       return ParseUnqualifiedIdTemplateId(
-          SS, TemplateKWLoc ? *TemplateKWLoc : SourceLocation(), nullptr,
-          SourceLocation(), EnteringContext, ObjectType, Result,
-          TemplateSpecified);
+          SS, ObjectType, ObjectHadErrors,
+          TemplateKWLoc ? *TemplateKWLoc : SourceLocation(), nullptr,
+          SourceLocation(), EnteringContext, Result, TemplateSpecified);
     else if (TemplateSpecified &&
              Actions.ActOnDependentTemplateName(
                  getCurScope(), SS, *TemplateKWLoc, Result, ObjectType,
                  EnteringContext, Template,
                  /*AllowInjectedClassName*/ true) == TNK_Non_template)
       return true;
 
     return false;
if (!TemplateSpecified && NextToken().is(tok::coloncolon)) {
       // `int A; struct { ~A::A(); };` to `int A; struct { ~A:A(); };`,
       // it will confuse this recovery logic.
       ColonProtectionRAIIObject ColonRAII(*this, false);
 
       if (SS.isSet()) {
         AnnotateScopeToken(SS, /*NewAnnotation*/true);
         SS.clear();
       }
-      if (ParseOptionalCXXScopeSpecifier(SS, ObjectType, EnteringContext))
+      if (ParseOptionalCXXScopeSpecifier(SS, ObjectType, ObjectHadErrors,
+                                         EnteringContext))
         return true;
       if (SS.isNotEmpty())
         ObjectType = nullptr;
       if (Tok.isNot(tok::identifier) || NextToken().is(tok::coloncolon) ||
           !SS.isSet()) {
         Diag(TildeLoc, diag::err_destructor_tilde_scope);
         return true;
       }
if (getLangOpts().CPlusPlus &&
 
     // Parse the class-name (or template-name in a simple-template-id).
     IdentifierInfo *ClassName = Tok.getIdentifierInfo();
     SourceLocation ClassNameLoc = ConsumeToken();
 
     if (Tok.is(tok::less)) {
       Result.setDestructorName(TildeLoc, nullptr, ClassNameLoc);
       return ParseUnqualifiedIdTemplateId(
-          SS, TemplateKWLoc ? *TemplateKWLoc : SourceLocation(), ClassName,
-          ClassNameLoc, EnteringContext, ObjectType, Result, TemplateSpecified);
+          SS, ObjectType, ObjectHadErrors,
+          TemplateKWLoc ? *TemplateKWLoc : SourceLocation(), ClassName,
+          ClassNameLoc, EnteringContext, Result, TemplateSpecified);
     }
 
     // Note that this is a destructor name.
     ParsedType Ty = Actions.getDestructorName(TildeLoc, *ClassName,
                                               ClassNameLoc, getCurScope(),
                                               SS, ObjectType,
                                               EnteringContext);
     if (!Ty)
       return true;
 
     Result.setDestructorName(TildeLoc, Ty, ClassNameLoc);
     return false;
   }
 
   Diag(Tok, diag::err_expected_unqualified_id)
     << getLangOpts().CPlusPlus;
   return true;
 }
 
+bool Parser::ParseUnqualifiedId(CXXScopeSpec &SS, bool EnteringContext,
+                                bool AllowDestructorName,
+                                bool AllowConstructorName,
+                                bool AllowDeductionGuide,
+                                SourceLocation *TemplateKWLoc,
+                                UnqualifiedId &Result) {
+  return ParseUnqualifiedId(SS, /*ObjectType=*/nullptr,
+                            /*ObjectHadErrors=*/false, EnteringContext,
+                            AllowDestructorName, AllowConstructorName,
+                            AllowDeductionGuide, TemplateKWLoc, Result);
+}
+
 /// ParseCXXNewExpression - Parse a C++ new-expression. New is used to allocate
 /// memory in a typesafe manner and call constructors.
 ///
 /// This method is called to parse the new expression after the optional :: has
 /// been already parsed.  If the :: was present, "UseGlobal" is true and "Start"
 /// is its location.  Otherwise, "Start" is the location of the 'new' token.
 ///
 ///        new-expression:

clang/lib/Parse/ParseOpenMP.cpp

bool Parser::ParseOpenMPSimpleVarList(
   while (Tok.isNot(tok::r_paren) && Tok.isNot(tok::annot_pragma_openmp_end)) {
     CXXScopeSpec SS;
     UnqualifiedId Name;
     // Read var name.
     Token PrevTok = Tok;
     NoIdentIsFound = false;
 
     if (AllowScopeSpecifier && getLangOpts().CPlusPlus &&
-        ParseOptionalCXXScopeSpecifier(SS, nullptr, false)) {
+        ParseOptionalCXXScopeSpecifier(SS, false)) {
       IsCorrect = false;
       SkipUntil(tok::comma, tok::r_paren, tok::annot_pragma_openmp_end,
                 StopBeforeMatch);
     } else if (ParseUnqualifiedId(SS, false, false, false, false, nullptr,
-                                  nullptr, Name)) {
+                                  Name)) {
       IsCorrect = false;
       SkipUntil(tok::comma, tok::r_paren, tok::annot_pragma_openmp_end,
                 StopBeforeMatch);
     } else if (Tok.isNot(tok::comma) && Tok.isNot(tok::r_paren) &&
                Tok.isNot(tok::annot_pragma_openmp_end)) {
       IsCorrect = false;
       SkipUntil(tok::comma, tok::r_paren, tok::annot_pragma_openmp_end,
                 StopBeforeMatch);
if (OOK != OO_None) {
       SourceLocation SymbolLocations[] = {OpLoc, OpLoc, SourceLocation()};
       ReductionId.setOperatorFunctionId(OpLoc, OOK, SymbolLocations);
       return false;
     }
   }
   return P.ParseUnqualifiedId(ReductionIdScopeSpec, /*EnteringContext*/ false,
                               /*AllowDestructorName*/ false,
                               /*AllowConstructorName*/ false,
-                              /*AllowDeductionGuide*/ false,
-                              nullptr, nullptr, ReductionId);
+                              /*AllowDeductionGuide*/ false, nullptr,
+                              ReductionId);
 }
 
 /// Checks if the token is a valid map-type-modifier.
 static OpenMPMapModifierKind isMapModifier(Parser &P) {
   Token Tok = P.getCurToken();
   if (!Tok.is(tok::identifier))
     return OMPC_MAP_MODIFIER_unknown;
 
bool Parser::parseMapperModifier(OpenMPVarListDataTy &Data) {
   if (T.expectAndConsume(diag::err_expected_lparen_after, "mapper")) {
     SkipUntil(tok::colon, tok::r_paren, tok::annot_pragma_openmp_end,
               StopBeforeMatch);
     return true;
   }
   // Parse mapper-identifier
   if (getLangOpts().CPlusPlus)
     ParseOptionalCXXScopeSpecifier(Data.ReductionOrMapperIdScopeSpec,
-                                   /*ObjectType=*/nullptr,
                                    /*EnteringContext=*/false);
   if (Tok.isNot(tok::identifier) && Tok.isNot(tok::kw_default)) {
     Diag(Tok.getLocation(), diag::err_omp_mapper_illegal_identifier);
     SkipUntil(tok::colon, tok::r_paren, tok::annot_pragma_openmp_end,
               StopBeforeMatch);
     return true;
   }
   auto &DeclNames = Actions.getASTContext().DeclarationNames;
bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
   BalancedDelimiterTracker LinearT(*this, tok::l_paren,
                                   tok::annot_pragma_openmp_end);
   // Handle reduction-identifier for reduction clause.
   if (Kind == OMPC_reduction || Kind == OMPC_task_reduction ||
       Kind == OMPC_in_reduction) {
     ColonProtectionRAIIObject ColonRAII(*this);
     if (getLangOpts().CPlusPlus)
       ParseOptionalCXXScopeSpecifier(Data.ReductionOrMapperIdScopeSpec,
-                                     /*ObjectType=*/nullptr,
                                      /*EnteringContext=*/false);
     InvalidReductionId = ParseReductionId(
         *this, Data.ReductionOrMapperIdScopeSpec, UnqualifiedReductionId);
     if (InvalidReductionId) {
       SkipUntil(tok::colon, tok::r_paren, tok::annot_pragma_openmp_end,
                 StopBeforeMatch);
     }
     if (Tok.is(tok::colon))

clang/lib/Parse/ParseStmtAsm.cpp

ExprResult Parser::ParseMSAsmIdentifier(llvm::SmallVectorImpl<Token> &LineToks,
   PP.EnterTokenStream(LineToks, /*DisableMacroExpansions*/ true,
                       /*IsReinject*/ true);
 
   // Clear the current token and advance to the first token in LineToks.
   ConsumeAnyToken();
 
   // Parse an optional scope-specifier if we're in C++.
   CXXScopeSpec SS;
-  if (getLangOpts().CPlusPlus) {
-    ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false);
-  }
+  if (getLangOpts().CPlusPlus)
+    ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false);
 
   // Require an identifier here.
   SourceLocation TemplateKWLoc;
   UnqualifiedId Id;
   bool Invalid = true;
   ExprResult Result;
   if (Tok.is(tok::kw_this)) {
     Result = ParseCXXThis();
     Invalid = false;
   } else {
-    Invalid = ParseUnqualifiedId(SS,
-                                 /*EnteringContext=*/false,
-                                 /*AllowDestructorName=*/false,
-                                 /*AllowConstructorName=*/false,
-                                 /*AllowDeductionGuide=*/false,
-                                 /*ObjectType=*/nullptr, &TemplateKWLoc, Id);
+    Invalid =
+        ParseUnqualifiedId(SS,
+                           /*AllowDeductionGuide=*/false, &TemplateKWLoc, Id);
     // Perform the lookup.
     Result = Actions.LookupInlineAsmIdentifier(SS, TemplateKWLoc, Id,
                                                IsUnevaluatedContext);
   }
   // While the next two tokens are 'period' 'identifier', repeatedly parse it as
   // a field access. We have to avoid consuming assembler directives that look
   // like '.' 'else'.
   while (Result.isUsable() && Tok.is(tok::period)) {

clang/lib/Parse/ParseTemplate.cpp

Parser::ParseConceptDefinition(const ParsedTemplateInfo &TemplateInfo,
   SourceLocation BoolKWLoc;
   if (TryConsumeToken(tok::kw_bool, BoolKWLoc))
     Diag(Tok.getLocation(), diag::ext_concept_legacy_bool_keyword) <<
         FixItHint::CreateRemoval(SourceLocation(BoolKWLoc));
 
   DiagnoseAndSkipCXX11Attributes();
 
   CXXScopeSpec SS;
-  if (ParseOptionalCXXScopeSpecifier(SS, ParsedType(),
-      /*EnteringContext=*/false, /*MayBePseudoDestructor=*/nullptr,
+  if (ParseOptionalCXXScopeSpecifier(
+          SS, /*EnteringContext=*/false, /*MayBePseudoDestructor=*/nullptr,
           /*IsTypename=*/false, /*LastII=*/nullptr, /*OnlyNamespace=*/true) ||
       SS.isInvalid()) {
     SkipUntil(tok::semi);
     return nullptr;
   }
 
   if (SS.isNotEmpty())
     Diag(SS.getBeginLoc(),
          diag::err_concept_definition_not_identifier);
 
   UnqualifiedId Result;
   if (ParseUnqualifiedId(SS, /*EnteringContext=*/false,
                          /*AllowDestructorName=*/false,
                          /*AllowConstructorName=*/false,
                          /*AllowDeductionGuide=*/false,
-                         /*ObjectType=*/ParsedType(), /*TemplateKWLoc=*/nullptr,
-                         Result)) {
+                         /*TemplateKWLoc=*/nullptr, Result)) {
     SkipUntil(tok::semi);
     return nullptr;
   }
 
   if (Result.getKind() != UnqualifiedIdKind::IK_Identifier) {
     Diag(Result.getBeginLoc(), diag::err_concept_definition_not_identifier);
     SkipUntil(tok::semi);
     return nullptr;

 ///
 /// \returns true if an error occurred, and false otherwise.
 bool Parser::TryAnnotateTypeConstraint() {
   if (!getLangOpts().CPlusPlus2a)
     return false;
   CXXScopeSpec SS;
   bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
   if (ParseOptionalCXXScopeSpecifier(
-          SS, ParsedType(),
+          SS, ParsedType(), /*ObjectHadErrors*/false,
           /*EnteringContext=*/false,
           /*MayBePseudoDestructor=*/nullptr,
           // If this is not a type-constraint, then
           // this scope-spec is part of the typename
           // of a non-type template parameter
           /*IsTypename=*/true, /*LastII=*/nullptr,
           // We won't find concepts in
           // non-namespaces anyway, so might as well
assert((Tok.isOneOf(tok::kw_class, tok::kw_typename) ||
           isTypeConstraintAnnotation()) &&
          "A type-parameter starts with 'class', 'typename' or a "
          "type-constraint");
 
   CXXScopeSpec TypeConstraintSS;
   TemplateIdAnnotation *TypeConstraint = nullptr;
   bool TypenameKeyword = false;
   SourceLocation KeyLoc;
-  ParseOptionalCXXScopeSpecifier(TypeConstraintSS, nullptr,
+  ParseOptionalCXXScopeSpecifier(TypeConstraintSS,
                                  /*EnteringContext*/ false);
   if (Tok.is(tok::annot_template_id)) {
     // Consume the 'type-constraint'.
     TypeConstraint =
         static_cast<TemplateIdAnnotation *>(Tok.getAnnotationValue());
     assert(TypeConstraint->Kind == TNK_Concept_template &&
            "stray non-concept template-id annotation");
     KeyLoc = ConsumeAnnotationToken();
ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
   // We parse an id-expression that refers to a class template or alias
   // template. The grammar we parse is:
   //
   //   nested-name-specifier[opt] template[opt] identifier ...[opt]
   //
   // followed by a token that terminates a template argument, such as ',',
   // '>', or (in some cases) '>>'.
   CXXScopeSpec SS; // nested-name-specifier, if present
-  ParseOptionalCXXScopeSpecifier(SS, nullptr,
-                                 /*EnteringContext=*/false);
+  ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false);
 
   ParsedTemplateArgument Result;
   SourceLocation EllipsisLoc;
   if (SS.isSet() && Tok.is(tok::kw_template)) {
     // Parse the optional 'template' keyword following the
     // nested-name-specifier.
     SourceLocation TemplateKWLoc = ConsumeToken();
 

clang/lib/Parse/Parser.cpp

 Parser::TryAnnotateName(CorrectionCandidateCallback *CCC) {
   assert(Tok.is(tok::identifier) || Tok.is(tok::annot_cxxscope));
 
   const bool EnteringContext = false;
   const bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
 
   CXXScopeSpec SS;
   if (getLangOpts().CPlusPlus &&
-      ParseOptionalCXXScopeSpecifier(SS, nullptr, EnteringContext))
+      ParseOptionalCXXScopeSpecifier(SS, EnteringContext))
     return ANK_Error;
 
   if (Tok.isNot(tok::identifier) || SS.isInvalid()) {
     if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation))
       return ANK_Error;
     return ANK_Unresolved;
   }
 
if (Tok.is(tok::kw_typename)) {
     // Parse a C++ typename-specifier, e.g., "typename T::type".
     //
     //   typename-specifier:
     //     'typename' '::' [opt] nested-name-specifier identifier
     //     'typename' '::' [opt] nested-name-specifier template [opt]
     //            simple-template-id
     SourceLocation TypenameLoc = ConsumeToken();
     CXXScopeSpec SS;
-    if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
-                                       /*EnteringContext=*/false, nullptr,
+    if (ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext=*/false, nullptr,
                                        /*IsTypename*/ true))
       return true;
     if (SS.isEmpty()) {
       if (Tok.is(tok::identifier) || Tok.is(tok::annot_template_id) ||
           Tok.is(tok::annot_decltype)) {
         // Attempt to recover by skipping the invalid 'typename'
         if (Tok.is(tok::annot_decltype) ||
             (!TryAnnotateTypeOrScopeToken() && Tok.isAnnotation())) {
if (Tok.is(tok::kw_typename)) {
     return false;
   }
 
   // Remembers whether the token was originally a scope annotation.
   bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
 
   CXXScopeSpec SS;
   if (getLangOpts().CPlusPlus)
-    if (ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext*/false))
+    if (ParseOptionalCXXScopeSpecifier(SS, /*EnteringContext*/ false))
       return true;
 
   return TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation);
 }
 
 /// Try to annotate a type or scope token, having already parsed an
 /// optional scope specifier. \p IsNewScope should be \c true unless the scope
 /// specifier was extracted from an existing tok::annot_cxxscope annotation.

 /// Note that this routine emits an error if you call it with ::new or ::delete
 /// as the current tokens, so only call it in contexts where these are invalid.
 bool Parser::TryAnnotateCXXScopeToken(bool EnteringContext) {
   assert(getLangOpts().CPlusPlus &&
          "Call sites of this function should be guarded by checking for C++");
   assert(MightBeCXXScopeToken() && "Cannot be a type or scope token!");
 
   CXXScopeSpec SS;
-  if (ParseOptionalCXXScopeSpecifier(SS, nullptr, EnteringContext))
+  if (ParseOptionalCXXScopeSpecifier(SS, EnteringContext))
     return true;
   if (SS.isEmpty())
     return false;
 
   AnnotateScopeToken(SS, true);
   return false;
 }
 
bool Parser::ParseMicrosoftIfExistsCondition(IfExistsCondition& Result) {
   if (T.consumeOpen()) {
     Diag(Tok, diag::err_expected_lparen_after)
       << (Result.IsIfExists? "__if_exists" : "__if_not_exists");
     return true;
   }
 
   // Parse nested-name-specifier.
   if (getLangOpts().CPlusPlus)
-    ParseOptionalCXXScopeSpecifier(Result.SS, nullptr,
-                                   /*EnteringContext=*/false);
+    ParseOptionalCXXScopeSpecifier(Result.SS, /*EnteringContext=*/false);
 
   // Check nested-name specifier.
   if (Result.SS.isInvalid()) {
     T.skipToEnd();
     return true;
   }
 
   // Parse the unqualified-id.
   SourceLocation TemplateKWLoc; // FIXME: parsed, but unused.
   if (ParseUnqualifiedId(
-          Result.SS, /*EnteringContext*/false, /*AllowDestructorName*/true,
-          /*AllowConstructorName*/true, /*AllowDeductionGuide*/false, nullptr,
+          Result.SS, /*EnteringContext*/ false, /*AllowDestructorName*/ true,
+          /*AllowConstructorName*/ true, /*AllowDeductionGuide*/ false,
           &TemplateKWLoc, Result.Name)) {
     T.skipToEnd();
     return true;
   }
 
   if (T.consumeClose())
     return true;
 

clang/lib/Sema/SemaTemplate.cpp

for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
     if (AllowNonTemplateFunctions &&
         isa<FunctionDecl>((*I)->getUnderlyingDecl()))
       return true;
   }
 
   return false;
 }
 
-TemplateNameKind Sema::isTemplateName(Scope *S,
-                                      CXXScopeSpec &SS,
-                                      bool hasTemplateKeyword,
-                                      const UnqualifiedId &Name,
-                                      ParsedType ObjectTypePtr,
-                                      bool EnteringContext,
-                                      TemplateTy &TemplateResult,
-                                      bool &MemberOfUnknownSpecialization) {
+TemplateNameKind
+Sema::isTemplateName(Scope *S, CXXScopeSpec &SS, bool hasTemplateKeyword,
+                     const UnqualifiedId &Name, ParsedType ObjectTypePtr,
+                     bool EnteringContext, TemplateTy &TemplateResult,
   assert(getLangOpts().CPlusPlus && "No template names in C!");
 
   DeclarationName TName;
   MemberOfUnknownSpecialization = false;
 
   switch (Name.getKind()) {
   case UnqualifiedIdKind::IK_Identifier:
     TName = DeclarationName(Name.Identifier);

clang/test/SemaTemplate/dependent-typos-recovery.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// There should be no extra errors about missing 'template' keywords.
+struct B {
+  template <typename T>
+  int f(){};
+} builder;                // expected-note 2{{'builder' declared here}}
+
+auto a = bilder.f<int>(); // expected-error{{undeclared identifier 'bilder'; did you mean}}
+auto b = (*(&bilder+0)).f<int>(); // expected-error{{undeclared identifier 'bilder'; did you mean}}