llvm-project

c1d8d0aa - Reapply "[Clang][Sema] Diagnose function/variable templates that shadow their own template parameters (#78274)" (#79683)

Reapply "[Clang][Sema] Diagnose function/variable templates that shadow their own template parameters (#78274)" (#79683) Reapplies #78274 with the addition of a default-error warning (`strict-primary-template-shadow`) that is issued for instances of shadowing which were previously accepted prior to this patch. I couldn't find an established convention for naming diagnostics related to compatibility with previous versions of clang, so I just used the prefix `ext_compat_`.