[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:

CC @erichkeane 

`clang_builtin_alias` is the only attribute we prefix in that way; I don't think it's a good precedent. GNU attributes are a shared namespace, but we have plenty of other examples where we define a GNU attribute that GCC doesn't support (overloadable, noderef, preferred_name, etc).

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