https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96673
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |11.0
Summary|[8/9/10/11 Regression] |[8/9/10 Regression] Friend
|Friend class with templates |class with templates and
|and default constructor not |default constructor not
|recognized in C++14 or |recognized in C++14 or
|later |later
--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 11 so far.