[clang] nonblocking/nonallocating attributes (was: nolock/noalloc) (PR #84983)

[Aaron Ballman via cfe-commits]

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@@ -1435,6 +1435,38 @@ def CXX11NoReturn : InheritableAttr {
   let Documentation = [CXX11NoReturnDocs];
 }
 
+def NonBlocking : TypeAttr {
+  let Spellings = [CXX11<"clang", "nonblocking">,
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AaronBallman wrote:

Yeah, Present Aaron regrets Past Aaron's caution there (there was a concern that `builtin_alias` really was plausibly going to be used by GCC but with a potentially different syntax, but that's the case with all attributes in the shared namespace, so I really shouldn't have asked for that prefix. Mea culpa!).

https://github.com/llvm/llvm-project/pull/84983