https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110421
--- Comment #1 from Dominik Gronkiewicz <gronki at gmail dot com> ---
Actually the minimal example can be cut down even further, to not introduce
confusion:
program main
implicit none
type :: typ1
end type
type, extends(typ1) :: typ1a
end type
type :: typ2
class(typ1), allocatable :: t1
end type
type(typ2) :: t2
! works
t2 = typ2(t1=typ1())
! crash
t2 = typ2(t1=typ1a())
end program
