[clang] [PAC] Implement authentication for C++ member function pointers (PR #99576)

[Oliver Hunt via cfe-commits]

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@@ -71,6 +71,15 @@ void has_ptrauth_vtable_pointer_type_discrimination() {}
 void no_ptrauth_vtable_pointer_type_discrimination() {}
 #endif
 
+// This is always enabled when ptrauth_calls is enabled, on new enough clangs.
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ojhunt wrote:

Weird mismerge I guess?

- [ ] fix the merge

https://github.com/llvm/llvm-project/pull/99576