[Bug fortran/98883] New: Module variable not initialized with -finit-real

[Bug fortran/98883] New: Module variable not initialized with -finit-real

[jellby at yahoo dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98883

            Bug ID: 98883
           Summary: Module variable not initialized with -finit-real
           Product: gcc
           Version: 7.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jellby at yahoo dot com
  Target Milestone: ---

I use -finit-real=nan hoping to catch some uninitialized variables, but
apparently variables in a module are not obeying this flag and are initialized
to something else (zero?):

!=================================
module foo
implicit none
real :: bar
end module foo

program test
use foo
implicit none
real :: w
write(6,*) w
w = bar
write(6,*) w
end program test
!=================================

$ gfortran -finit-real=nan a.f90 && ./a.out 
              NaN
   0.00000000

So, the first printout shows the unitialized w, correctly set to NaN. The
second printout should be the variable in the module, which is zero for some
reason.

[Bug fortran/98883] Module variable not initialized with -finit-real

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98883

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
           Severity|normal                      |enhancement
   Last reconfirmed|                            |2021-01-29
           Priority|P3                          |P4

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Confirmed.

[Bug fortran/98883] Module variable not initialized with -finit-real

[kargl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98883

kargl at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P4                          |P5
                 CC|                            |kargl at gcc dot gnu.org

--- Comment #2 from kargl at gcc dot gnu.org ---
This bug report should be closed.

Please read the description of option that you are using.

-freal-init=nan applies to **** LOCAL ***** variables.
'bar' is not local to program test, and clearly the option
does not affect variables made available via USE association.

[Bug fortran/98883] Module variable not initialized with -finit-real

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98883

--- Comment #3 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Fri, Jan 29, 2021 at 06:55:16PM +0000, kargl at gcc dot gnu.org wrote:
> 
> --- Comment #2 from kargl at gcc dot gnu.org ---
> This bug report should be closed.
> 
> Please read the description of option that you are using.
> 
> -freal-init=nan applies to **** LOCAL ***** variables.
> 'bar' is not local to program test, and clearly the option
> does not affect variables made available via USE association.
> 

I'll also point out that 'bar' is local module
to the module, but as it is unused gfortran 
won't initialize it via -finit-real=nan.  If you 
actual use it, it gets initialized.

module foo
  implicit none
  real :: bar
  contains
    subroutine bah
      real boo
      boo = bar ! <-- Sufficient to get bar = NaN
      print *, boo
    end subroutine bah
end module foo

program test
  use foo
  implicit none
  real w
  print *, w
  w = bar
  print *, w
end program test