[Bug c++/120287] [12/13/14/15/16 Regression] internal compiler error: tree check: expected class 'type', have 'exceptional' (error_mark) in is_std_substitution, at cp/mangle.cc:507

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120287

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I guess it depends on what approach is used to fix this.
If just handling error_mark_node gracefully during the mangling (emit something
in that case, what exactly doesn't matter much) and/or somehow figure out that
the to be mangled entity (whether variable template or function template etc.)
is somehow erroneous and don't try to mangle it at all.
If the former, then it is the same bug...