[Bug fortran/47030] New: !GCC$ Attributes do not work for COMMON variables in procedures and BLOCK DATA

[Bug fortran/47030] New: !GCC$ Attributes do not work for COMMON variables in procedures and BLOCK DATA

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47030

           Summary: !GCC$ Attributes do not work for COMMON variables in
                    procedures and BLOCK DATA
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org


Cf. report by Arjen Markus at
http://gcc.gnu.org/ml/fortran/2010-12/msg00124.html  -- There is also a Windows
example.

Under Linux DLLEXPORT is not supported and thus there is a warning, which makes
testing very convenient. If I do now:
!-------------------------
subroutine print
   real :: x
!GCC$ attributes dllexport :: mydata
   common /mydata/ x

   write(*,*) 'X = ', x

end subroutine print
!-------------------------

it simply compiles - i.e. the DLLEXPORT is ignored. However, if I use:

!-------------------------
module m
   real :: x
   common /mydata/ x
   !GCC$ attributes dllexport :: mydata
end module
!-------------------------

I get the warning:

  f951: warning: ‘dllexport’ attribute directive ignored [-Wattributes]

Which directly implies that the attribute it not taken into account for COMMON
blocks defined in SUBROUTINE/FUNCTION.


Same problem for BLOCK DATA: No warning for

      block data
        real alpha, beta
        common /vector/ alpha,beta
        data alpha/3.14/, beta/2.71/
!GCC$ attributes dllexport :: vector
      end

[Bug fortran/47030] !GCC$ Attributes do not work for COMMON variables in procedures and BLOCK DATA

[dfranke at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47030

Daniel Franke <dfranke at gcc dot gnu.org> changed:

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

--- Comment #1 from Daniel Franke <dfranke at gcc dot gnu.org> 2010-12-27 23:34:45 UTC ---
Is this related to/dupe of PR42568?

[Bug fortran/47030] !GCC$ Attributes do not work for COMMON variables in procedures and BLOCK DATA

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47030

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-01-07 22:22:15 UTC ---
Created attachment 22930
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22930
Draft patch

Draft patch attached (untested).
TODO: Warn if the same COMMON block has different ext_attr in different scopes
of the same translation unit.

 * * *

(In reply to comment #1)
> Is this related to/dupe of PR42568?

No - those are different issues.

[Bug fortran/47030] !GCC$ Attributes do not work for COMMON variables in procedures and BLOCK DATA

[eh.toussaint at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47030

Erik Toussaint <eh.toussaint at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |eh.toussaint at gmail dot
                   |                            |com

--- Comment #3 from Erik Toussaint <eh.toussaint at gmail dot com> 2012-03-02 22:17:52 UTC ---
(In reply to comment #0)

For both program units, if I add 'implicit none' I get the following error:

!GCC$ attributes dllexport :: mydata
                                    1
Error: Symbol 'mydata' at (1) has no IMPLICIT type

So 'mydata' is treated as the identifier of a local entity. Which makes sense,
because a common block and a local entity can have the same name (with certain
restrictions; see 16.3.1 and 16.3.2 in f2008).

Looking at the syntax of the Intel Fortran compiler, the name of the common
block has to be between slashes:

!DEC$ ATTRIBUTES DLLEXPORT :: /X/

http://software.intel.com/sites/products/documentation/hpc/compilerpro/en-us/fortran/win/compiler_f/bldaps_for/win/bldaps_share_datadlls.htm

Trying this with gfortran gives an error:

!GCC$ attributes dllexport :: /mydata/
                               1
Error: Invalid character in name at (1)


P.s.:

> !-------------------------
> module m
>    real :: x
>    common /mydata/ x
>    !GCC$ attributes dllexport :: mydata
> end module
> !-------------------------
> 
> I get the warning:
> 
>   f951: warning: ‘dllexport’ attribute directive ignored [-Wattributes]

I get an error (I'm using MinGW GCC 4.6.2):

m.f90:5:0: error: external linkage required for symbol 'mydata' because of
'dlle
xport' attribute

[Bug fortran/47030] !GCC$ Attributes do not work for COMMON variables in procedures and BLOCK DATA

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47030

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2015-10-21
     Ever confirmed|0                           |1

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Compiling the first test with -Wall gives the warning

 !GCC$ attributes dllexport :: mydata
                                    1
Warning: Unused variable 'mydata' declared at (1) [-Wunused-variable]

for 5.2.0 and 6.0, without ' [-Wunused-variable]' for 4.8 and 4.9.

Compiling the second test gives

f951: warning: 'dllexport' attribute directive ignored [-Wattributes]

for 4.8 and 4.9 and an ICE for 5.2.0 and 6.0 (pr68040).

I don't get any warning for the third test for 4.8 up to trunk (6.0).