[clang] [Clang] Add [[clang::diagnose_specializations]] (PR #101469)

[Aaron Ballman via cfe-commits]

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@@ -3327,6 +3330,15 @@ def DiagnoseIf : InheritableAttr {
   let Documentation = [DiagnoseIfDocs];
 }
 
+def DiagnoseSpecializations : InheritableAttr {
+  let Spellings = [Clang<"diagnose_specializations", /*AllowInC*/0>];
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AaronBallman wrote:

Should this be named `diagnose_explicit_specializations` given: https://eel.is/c++draft/temp.spec#general-4.sentence-2

https://github.com/llvm/llvm-project/pull/101469