[Bug c++/100629] Regression from 10 symbol mismatch between class definition and use with optimization

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100629

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I suspect that one file only sees a forward declaration of complement_names
(without the abi_tag) and the other file sees the definition (with the
abi_tag). The question is why the tag is on that type at all, but without
preprocessed sources we can only guess.