[Bug fortran/93263] New: -fno-automatic and RECURSIVE

[gcc.bugzilla at he dot sk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93263

            Bug ID: 93263
           Summary: -fno-automatic and RECURSIVE
           Product: gcc
           Version: 9.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc.bugzilla at he dot sk
  Target Milestone: ---

The combination of -fno-automatic and RECURSIVE does not seem to behave
correctly in gfortran 9.2.1. 

The output of the following program depends on whether it is compiled with or
without -fno-automatic, while according to the manual it should not.

      program main
      implicit none
      call check(2)
      end 

      recursive subroutine check(n)
      implicit none
      integer n, a
      a = 10
      print*,"n=",n
      if (n==1) then
         a=a-1
         print*,"assigning a=",a
      else
         a=a-2
         print*,"assigning a=",a
         call check(n-1)
      endif
      print*,"a=",a
      end 

Output without -fno-automatic:
 n=           2
 assigning a=           8
 n=           1
 assigning a=           9
 a=           9
 a=           8

Output with -fno-automatic:
 n=           2
 assigning a=           8
 n=           1
 assigning a=           9
 a=           9
 a=           9

It seems like with -fno-automatic the variable a is not AUTOMATIC while
according to the manual it should because the relevant program unit is marked
as RECURSIVE:

-fno-automatic

    Treat each program unit (except those marked as RECURSIVE) as if the SAVE
statement were specified for every local variable and array referenced in it.
Does not affect common blocks. (Some Fortran compilers provide this option
under the name -static or -save.) The default, which is -fautomatic, uses the
stack for local variables smaller than the value given by -fmax-stack-var-size.
Use the option -frecursive to use no static memory. 

https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html

Note that this behaviour changes with respect to previous versions of gfortran.

Thanks!

Tomas