[Bug fortran/98141] Segmentation fault with empty string sourced allocation

[davidhneill at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98141

--- Comment #1 from David Neill Asanza <davidhneill at gmail dot com> ---
Here are even shorter examples:

$ cat short01.f90

program short01
  class(*), allocatable :: a, b, c
  character(len=0) :: s
  allocate(a, source=s)  !! No problem
  allocate(character(len=0)::b)
  allocate(c, source=b)  !! Segfault
end program

$ cat short02.f90

program short02
  class(*), allocatable :: a, b
  allocate(a, source='')  !! No problem
  allocate(b, source=a)   !! Segfault
end program


So it seems the underlying issue is the sourced allocation from a 0-length
unlimited polymorphic type.