[PATCH] D65256: [Sema][ObjC] Mark C union fields that have non-trivial ObjC ownership qualifications as unavailable if the union is declared in a system header

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak added inline comments.


================
Comment at: lib/Sema/SemaDecl.cpp:11144
+  // Ignore unavailable fields since they don't affect the triviality of the
+  // containing struct/union.
+  return FD->hasAttr<UnavailableAttr>();
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rjmccall wrote:
> The "since" clause here is circular: this function *defines* what affects the triviality.  The comment should talk about the motivations (e.g. fields that aren't available in particular language modes) and why this might be okay or is the best-available option (despite e.g. the potential for ABI incompatibility across language modes),
I commented on the ABI incompatibility issue in `ActOnFields` where the unavailable attribute is added to the field.


Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65256/new/

https://reviews.llvm.org/D65256