1 files changed, 60 insertions, 25 deletions

diff --git a/clang/lib/Parse/ParseTemplate.cpp b/clang/lib/Parse/ParseTemplate.cpp
index 9a04bf2..0277dfb 100644
--- a/clang/lib/Parse/ParseTemplate.cpp
+++ b/clang/lib/Parse/ParseTemplate.cpp
@@ -711,41 +711,61 @@ NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
     }
   }
 
-  // Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
-  // Generate a meaningful error if the user forgot to put class before the
-  // identifier, comma, or greater. Provide a fixit if the identifier, comma,
-  // or greater appear immediately or after 'struct'. In the latter case,
-  // replace the keyword with 'class'.
+  TemplateNameKind Kind = TemplateNameKind::TNK_Non_template;
+  SourceLocation NameLoc;
+  IdentifierInfo *ParamName = nullptr;
+  SourceLocation EllipsisLoc;
   bool TypenameKeyword = false;
-  if (!TryConsumeToken(tok::kw_class)) {
+
+  if (TryConsumeToken(tok::kw_class)) {
+    Kind = TemplateNameKind::TNK_Type_template;
+  } else {
+
+    // Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
+    // Generate a meaningful error if the user forgot to put class before the
+    // identifier, comma, or greater. Provide a fixit if the identifier, comma,
+    // or greater appear immediately or after 'struct'. In the latter case,
+    // replace the keyword with 'class'.
     bool Replace = Tok.isOneOf(tok::kw_typename, tok::kw_struct);
     const Token &Next = Tok.is(tok::kw_struct) ? NextToken() : Tok;
     if (Tok.is(tok::kw_typename)) {
       TypenameKeyword = true;
+      Kind = TemplateNameKind::TNK_Type_template;
       Diag(Tok.getLocation(),
            getLangOpts().CPlusPlus17
                ? diag::warn_cxx14_compat_template_template_param_typename
                : diag::ext_template_template_param_typename)
-        << (!getLangOpts().CPlusPlus17
-                ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
-                : FixItHint());
+          << (!getLangOpts().CPlusPlus17
+                  ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
+                  : FixItHint());
+      Kind = TemplateNameKind::TNK_Type_template;
+    } else if (TryConsumeToken(tok::kw_concept)) {
+      Kind = TemplateNameKind::TNK_Concept_template;
+    } else if (TryConsumeToken(tok::kw_auto)) {
+      Kind = TemplateNameKind::TNK_Var_template;
     } else if (Next.isOneOf(tok::identifier, tok::comma, tok::greater,
                             tok::greatergreater, tok::ellipsis)) {
+      // Provide a fixit if the identifier, comma,
+      // or greater appear immediately or after 'struct'. In the latter case,
+      // replace the keyword with 'class'.
       Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
           << getLangOpts().CPlusPlus17
           << (Replace
                   ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
                   : FixItHint::CreateInsertion(Tok.getLocation(), "class "));
-    } else
-      Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
-          << getLangOpts().CPlusPlus17;
-
+    }
     if (Replace)
       ConsumeToken();
   }
 
+  if (!getLangOpts().CPlusPlus26 &&
+      (Kind == TemplateNameKind::TNK_Concept_template ||
+       Kind == TemplateNameKind::TNK_Var_template)) {
+    Diag(PrevTokLocation, diag::err_cxx26_template_template_params)
+        << (Kind == TemplateNameKind::TNK_Concept_template);
+  }
+
   // Parse the ellipsis, if given.
-  SourceLocation EllipsisLoc;
   if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
     Diag(EllipsisLoc,
          getLangOpts().CPlusPlus11
@@ -753,8 +773,7 @@ NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
            : diag::ext_variadic_templates);
 
   // Get the identifier, if given.
-  SourceLocation NameLoc = Tok.getLocation();
-  IdentifierInfo *ParamName = nullptr;
+  NameLoc = Tok.getLocation();
   if (Tok.is(tok::identifier)) {
     ParamName = Tok.getIdentifierInfo();
     ConsumeToken();
@@ -792,7 +811,7 @@ NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
   }
 
   return Actions.ActOnTemplateTemplateParameter(
-      getCurScope(), TemplateLoc, ParamList, TypenameKeyword, EllipsisLoc,
+      getCurScope(), TemplateLoc, Kind, TypenameKeyword, ParamList, EllipsisLoc,
       ParamName, NameLoc, Depth, Position, EqualLoc, DefaultArg);
 }
 
@@ -1201,7 +1220,8 @@ static bool isEndOfTemplateArgument(Token Tok) {
 
 ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
   if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
-      !Tok.is(tok::annot_cxxscope))
+      !Tok.is(tok::annot_cxxscope) && !Tok.is(tok::annot_template_id) &&
+      !Tok.is(tok::annot_non_type))
     return ParsedTemplateArgument();
 
   // C++0x [temp.arg.template]p1:
@@ -1245,12 +1265,27 @@ ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
                                     /*EnteringContext=*/false, Template))
         Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
     }
-  } else if (Tok.is(tok::identifier)) {
+  } else if (Tok.is(tok::identifier) || Tok.is(tok::annot_template_id) ||
+             Tok.is(tok::annot_non_type)) {
     // We may have a (non-dependent) template name.
     TemplateTy Template;
     UnqualifiedId Name;
-    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
-    ConsumeToken(); // the identifier
+    if (Tok.is(tok::annot_non_type)) {
+      NamedDecl *ND = getNonTypeAnnotation(Tok);
+      if (!isa<VarTemplateDecl>(ND))
+        return Result;
+      Name.setIdentifier(ND->getIdentifier(), Tok.getLocation());
+      ConsumeAnnotationToken();
+    } else if (Tok.is(tok::annot_template_id)) {
+      TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
+      if (TemplateId->LAngleLoc.isValid())
+        return Result;
+      Name.setIdentifier(TemplateId->Name, Tok.getLocation());
+      ConsumeAnnotationToken();
+    } else {
+      Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
+      ConsumeToken(); // the identifier
+    }
 
     TryConsumeToken(tok::ellipsis, EllipsisLoc);
 
@@ -1261,7 +1296,8 @@ ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
           /*hasTemplateKeyword=*/false, Name,
           /*ObjectType=*/nullptr,
           /*EnteringContext=*/false, Template, MemberOfUnknownSpecialization);
-      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
+      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template ||
+          TNK == TNK_Var_template || TNK == TNK_Concept_template) {
         // We have an id-expression that refers to a class template or
         // (C++0x) alias template.
         Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
@@ -1301,13 +1337,12 @@ ParsedTemplateArgument Parser::ParseTemplateArgument() {
   {
     TentativeParsingAction TPA(*this);
 
-    ParsedTemplateArgument TemplateTemplateArgument
-      = ParseTemplateTemplateArgument();
+    ParsedTemplateArgument TemplateTemplateArgument =
+        ParseTemplateTemplateArgument();
     if (!TemplateTemplateArgument.isInvalid()) {
       TPA.Commit();
       return TemplateTemplateArgument;
     }
-
     // Revert this tentative parse to parse a non-type template argument.
     TPA.Revert();
   }