https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90102
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-04-16
Ever confirmed|0 |1
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It's definitely a library bug. The problem is shown by the diagnostic messages.
A DEBUG::debug vector can be constructed from a NORMAL::vector, because it has
an extra constructor. Your conversion operator allows your type to convert to
either DEBUG::vector or NORMAL::vector. Both of those types can convert to
DEBUG::vector, so there are two equally good conversion sequences, which is
ambiguous.
