[clang] [clang][Parser] "Better" error messages for invalid template template (PR #95726)

[via cfe-commits]

================
@@ -787,6 +787,20 @@ NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
                                                   unsigned Position) {
   assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");
 
+  if (Token ahead = GetLookAheadToken(1); ahead.isNot(tok::less)) {
----------------
Sirraide wrote:

Ah yes, you can tell I don’t review parser code too often because I probably should have noticed that haha.

https://github.com/llvm/llvm-project/pull/95726