https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106758
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Benjamin Brock from comment #0)
> The following concept is failing, saying that `bar({{12, 12}, 12})` is an
> invalid expression. I believe it is a valid expression, just with a
> narrowing conversion inside it.
In a list-initialization context a narrowing conversion is ill-formed. So it's
not a valid expression.
