[clang-tools-extra] [clang] [Attributes][HLSL] Teach EnumArgument to refer to an external enum (PR #70835)

[Aaron Ballman via cfe-commits]

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@@ -279,12 +279,13 @@ class DefaultIntArgument<string name, int default> : IntArgument<name, 1> {
 
 // This argument is more complex, it includes the enumerator type name,
 // a list of strings to accept, and a list of enumerators to map them to.
-class EnumArgument<string name, string type, list<string> values,
+class EnumArgument<string name, string type, bit ext, list<string> values,
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AaronBallman wrote:

> > Should we also consider updating https://clang.llvm.org/docs/InternalsManual.html#arguments to explain this particular argument in more detail given that it's a pretty complicated argument already?
> 
> Looks like this doesn't go into detail about the types of arguments at all currently. I'll put a note on my todo list to update this separately if you don't mind.

Yeah, I never documented the argument types because they used to be rather self-documenting in a lot of ways. We should have started updating these docs a while ago though. Doing it in a follow-up is fine by me (and even if you only do `EnumArgument`; I'm not asking you to sign up to document them all unless you want to).

https://github.com/llvm/llvm-project/pull/70835