[PATCH] D67028: Use musttail for variadic method thunks when possible

[Eli Friedman via Phabricator via cfe-commits]

efriedma added a comment.

> In the MS ABI, deriving a new class may require the creation of new thunks for methods that were not overridden, so we can't use the same trick.

Yes.  MSVC emits an error message "covariant returns with multiple or virtual inheritance not supported for varargs functions" in cases like the following.   It looks like the equivalent isn't implemented in clang?  (Is that the llvm_unreachable in this patch?)


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https://reviews.llvm.org/D67028