[Bug c++/125711] [14/15/16/17 Regression] internal compiler error: tree check: expected class 'expression', have 'declaration' (var_decl) in tree_operand_check, at tree.h:4349

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125711

--- Comment #4 from Drea Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Iain Sandoe from comment #3)
> hmm .. the reduced case involves neither coroutines nor contracts;  I will
> try to repo. locally and take an initial look.

I was suspecting that patch because it touches the gimplifier. 
There is one change which looks suspect:
- if (!gimple_seq_empty_p (n) && !gimple_seq_empty_p (e))
+ if (!gimple_seq_empty_p (n) || !gimple_seq_empty_p (e))