[Bug c++/83739] error: range-based 'for' expression of type 'auto' has incomplete type

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83739

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
There's no way all that code is relevant to the problem.

https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction