https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85977
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Seems like deducing the template parameter N fails because of the type
mismatch; parm is long int (element type of the array), while arg is int
(element type of {1, 2, 3}):
21789 /* We have already checked cv-qualification at the top of the
21790 function. */
21791 if (!same_type_ignoring_top_level_qualifiers_p (arg, parm))
21792 return unify_type_mismatch (explain_p, parm, arg);
I guess here's where [over.ics.list]/6 applies so we should try an implicit
conversion sequence from int to long.
