https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89537
--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
loc is UNKNOWN_LOCATION:
(gdb) up
#1 0x0000000000b98003 in invalid_nonstatic_memfn_p (loc=0, expr=<function_decl
0x7fffeaaf8000 keys>,
complain=3) at /home/mpolacek/src/gcc/gcc/cp/typeck.c:1896
1896 error_at (loc, "invalid use of non-static member function
%qD",
(gdb) p loc
$1 = 0
