[clang] [clang] require template arg list after template kw (PR #80801)

[Vlad Serebrennikov via cfe-commits]

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@@ -1414,7 +1414,7 @@ namespace dr96 { // dr96: no
     // FIXME: This is ill-formed, because 'f' is not a template-id and does not
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Endilll wrote:

@opensdh Thank you for the clarification. I guess I read [N1528](https://wg21.link/n1528)
Would it be a correct statement to make that you deprecated the following case described in that paper?
> Consequently, the recommendation of this paper is: If the template keyword is followed by a name that does not have a template-argument-list, the name must refer to a class template and be used in a context in which a class template is valid, otherwise the program is ill-formed. 

https://github.com/llvm/llvm-project/pull/80801