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

[Erick Velez 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
     // name a class template.
     // FIXME: What about alias templates?
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evelez7 wrote:

The use of 'template' before an alias template is [deprecated](https://eel.is/c++draft/depr.template.template), along with before a class template. I wasn't sure how to interpret this for clang, they aren't errors yet?

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