[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>];
+  let Args = [StringArgument<"Message", 1>];
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AaronBallman wrote:

Do we want to allow the user to decide between warning vs error like we do for `diagnose_if`?

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