[Bug fortran/66575] New: Endless compilation on missing end interface

[gerhard.steinmetz.fortran@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66575

            Bug ID: 66575
           Summary: Endless compilation on missing end interface
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gerhard.steinmetz.fortran@t-online.de
  Target Milestone: ---

If the first "end interface" is missing :

$ cat zlcti_1.f90
   module m
      interface operator (.f.)
         procedure f
      !end interface
      interface operator (.g.)
         procedure g
      end interface
   contains
      integer function f(x)
         integer, intent(in) :: x
         f = x
      end function
      integer function g(x)
         integer, intent(in) :: x
         g = x
      end function
   end


or wrong for whatever reason, e.g. :

$ cat zlcti_2.f90
   module m
      interface operator (.f.)
         procedure f
      end !interface
      interface operator (.g.)
         procedure g
      end interface
   contains
      integer function f(x)
         integer, intent(in) :: x
         f = x
      end function
      integer function g(x)
         integer, intent(in) :: x
         g = x
      end function
   end


then compilation will not end, even after minutes.

$ time gfortran -c zlcti_1.f90
# ^C after a few minutes

real    5m10.508s
user    0m0.000s
sys     0m0.001s

Tested with gfortran 5.1.1, 4.9.0, 4.8.3 (on SUSE Linux 13.2, 64 bit).
Tested with several combinations of options and several flags.