Proposed patch to 13249

[Steve Kargl]

On Sun, May 16, 2004 at 05:18:52PM +0300, Victor Leikehman wrote:
> 
> A variable that is both defined in a module, and used as common
> block name,  triggers error message "Cannot change attributes of
> USE-associated symbol".  For example, the following (valid) code
> is rejected:
> 
>   MODULE MOD
>   INTEGER FOO
>   END
>   PROGRAM MAIN
>   USE MOD
>   COMMON /FOO/ BAR
>   END

(snip)

> 
> Function gfc_add_common, in file symbol.c, says:
> 
> gfc_add_common (symbol_attribute * attr, locus * where)
> {
>   if (check_used (attr, where) || check_done (attr, where))
>       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>     return FAILURE;
> 
>   attr->common = 1;
>   return check_conflict (attr, where);
> }
> 
> The call to check_used() checks the "use" attribute, which
> is 1 for variables defined in modules.  I can't understand
> why this check is necessary.  Removing the call to check_used
> apparently fixes the problem and does not cause regressions,
> BUT I guess it is there for a purpose...
> 
> If nobody can see why this check is needed, I will submit the
> patch.

Victor,

I think the check is there for this modified program

  MODULE MOD
  INTEGER FOO
  END
  PROGRAM MAIN
  USE MOD
  COMMON /BAR/ FOO
  END

This is NAG's compiler
kargl[222] f95 -o r r.f90
Error: r.f90, line 6: Redeclaration of symbol FOO from USEd module
       detected at /@FOO
[f95 terminated - errors found by pass 1]

This is gfortran and it prints the error message you quoted.
kargl[223] gfc -o r r.f90
 In file r.f90:6

  COMMON /BAR/ FOO
                 1
Error: Cannot change attributes of USE-associated symbol at (1)

I suspect the if (...) needs to check that the FOO in your
"COMMON /FOO/ BAR" is not the name of a COMMON block.

-- 
Steve