[clang] [clang]Implement the c23 stdc bit builtins (PR #185978)

[Erich Keane via cfe-commits]

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@@ -2345,6 +2345,47 @@ static bool BuiltinPopcountg(Sema &S, CallExpr *TheCall) {
   return false;
 }
 
+/// Checks stdc bit-utility builtins (__builtin_stdc_*):
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erichkeane wrote:

Can we not do the list?  That  has the amazing ability to get out of sync one day :) 

Perhaps just say the 'set of __builtin_stdc_ builtins that take a single unsigned integer and return either int, bool, or argument type'.

https://github.com/llvm/llvm-project/pull/185978