[Bug c/88727] Diagnostics improvement: Detection of undefined behaviour. Incomplete type in tenative definition with internal linkage.

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88727

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot 
com> ---
This was the case mentioned in bug 26581 comment 4, but without a separate 
bug filed for it at the time.