[Bug fortran/66545] ICE on using undefined parameter/variable values

["gerhard dot steinmetz dot fortran at t-online dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66545

--- Comment #1 from Gerhard Steinmetz <gerhard.steinmetz.fortran@t-online.de> ---
Trivially, the following cases behave similar :


$ cat z1_real.f90
program p
   real, parameter :: c1 = (c1)
   real, parameter :: c2 = c2
   real :: c3 = (c3)
   real :: c4 = c4
   real :: c5
   real :: c6
   c5 = (c5)
   c6 = c6
end


$ cat z1_integer.f90
program p
   integer, parameter :: c1 = (c1)
   integer, parameter :: c2 = c2
   integer :: c3 = (c3)
   integer :: c4 = c4
   integer :: c5
   integer :: c6
   c5 = (c5)
   c6 = c6
end


$ cat z1_logical.f90
program p
   logical, parameter :: c1 = (c1)
   logical, parameter :: c2 = c2
   logical :: c3 = (c3)
   logical :: c4 = c4
   logical :: c5
   logical :: c6
   c5 = (c5)
   c6 = c6
end


$ cat z1_character.f90
program p
   character, parameter :: c1 = (c1)
   character, parameter :: c2 = c2
   character :: c3 = (c3)
   character :: c4 = c4
   character :: c5
   character :: c6
   c5 = (c5)
   c6 = c6
end


$ cat z1_type.f90
program p
   type t; end type
   type(t), parameter :: c1 = (c1)
   type(t), parameter :: c2 = c2
   type(t) :: c3 = (c3)
   type(t) :: c4 = c4
   type(t) :: c5
   type(t) :: c6
   c5 = (c5)
   c6 = c6
end