[clang] [Parser][ObjC] Add -Wobjc-prefix-length warning option. (PR #97597)

[Jon Roelofs via cfe-commits]

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@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 %s -Wobjc-prefixes=NS,NSCF,NSURL -fsyntax-only -verify
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jroelofs wrote:

is it worth adding a `-Wobjc-forbidden-prefixes=NS`, so you can e.g. forbid things outside of Foundation from defining things with the `NS` prefix?

https://github.com/llvm/llvm-project/pull/97597