[Bug fortran/77602] ICE with cyclic length declaration: Killed (program f951)

["kargl at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77602

kargl at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kargl at gcc dot gnu.org

--- Comment #2 from kargl at gcc dot gnu.org ---
"cyclic" is the wrong word.

subroutine s(x)                    ! line 1
   implicit character (a-z)        ! line 2
   character(len=len(y)+1) :: x    ! line 3
   character(len=len(x)+1) :: y    ! line 4
end                                ! line 5


line 2 causes the first reference to 'y' to 
give 'y' an implicit type of CHARACTER(1), so
'x' in line 3 has len=2.  'y' may appear in
a subsequent declaration where that declaration
confirms the type.  Hmmm, this took awhile to
find (F2003, p126):

  A variable in a specification expression shall have its type
  and type parameters, if any, specified by a previous declaration
  in the same scoping unit, by the implicit typing rules in effect
  for the scoping unit, or by host or use association. If a variable
  in a specification expression is typed by the implicit typing
  rules, its appearance in any subsequent type declaration statement
  shall confirm the implied type and type parameters.

This is not a numbered constraint.  The requirement is on the
programmer to get it right.  So, yes, the code is invalid, and
gfortran can do anything it wants including ICE.