[libcxx-commits] [libcxx] [libcxxabi] [libc++][libc++abi] Minor follow-up changes after ptrauth upstreaming (PR #87481)

[Daniil Kovalev via libcxx-commits]

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@@ -275,13 +275,15 @@ struct __type_info_implementations {
           __impl;
 };
 
-#    if defined(__arm64__) && __has_cpp_attribute(clang::ptrauth_vtable_pointer)
-#      if __has_feature(ptrauth_type_info_discriminated_vtable_pointer)
+#    if __has_cpp_attribute(_Clang::__ptrauth_vtable_pointer__) && __has_feature(__ptrauth_calls__)
+#      if __has_feature(__ptrauth_vtable_address_discrimination__) ||                                                  \
+          __has_feature(__ptrauth_vtable_type_discrimination__)
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kovdan01 wrote:

@ldionne @ahmedbougacha @asl
**Update.** My preference is the following:
1. Do not check arm64/aarch64. If in future we have ptrauth support on non-arm64, for example, via soft pointer auth, the conditions will remain the same. Since we don't have different logic for ptrauth+non-arm64, no need for additional check.
2. Do not check against `ptrauth_calls`. The `[[clang::ptrauth_vtable_pointer]]` attribute has no effect w/o `ptrauth_calls` enabled.
3. If we want to introduce `__has_feature(ptrauth_type_info_discriminated_vtable_pointer)`, @ahmedbougacha please update your branch to include changes allowing such discrimination - now there is no support on clang side.

https://github.com/llvm/llvm-project/pull/87481