[Bug c++/90462] Internal compiler error with deprecated-copy and json diagnostics

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90462

--- Comment #4 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
r271535 should fix the ICE on trunk, but it doesn't fix the missing "finish"
location for the warning described in comment #2.