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Re: [Patch, Fortran, OOP] PR 44541: wrong code for polymorphic variable with INTENT(OUT)/Alloc w/ MOLD


Am 01.09.2010 19:39, schrieb Steve Kargl:
On Wed, Sep 01, 2010 at 07:01:02PM +0200, Tobias Burnus wrote:
The question is: Why are INTENT(OUT) variables already assigned a value?
[...]
16.5.5
(23) Invocation of a procedure that has a nonpointer nonallocatable
      INTENT (OUT) dummy argument causes all nonpointer default-initialized
      subcomponents of the dummy argument to become defined.
Note there are restrictions on optional arguments.

Thanks for the reminder of optional arguments; still, I am not sure what your answer is supposed to tell me.


My point was that - even without touching a derived-type intent-out dummy variable, it gets initialized. (As required by the standard.) Thus, it works even if the code the following code is not executed as attr.referenced is false:

  if (sym->ts.type == BT_DERIVED
&& sym->attr.referenced
&& sym->ns == gfc_current_ns
&& !sym->value
&& !sym->attr.allocatable
&& !sym->attr.alloc_comp)
    {
      symbol_attribute *a = &sym->attr;

      if ((!a->save && !a->dummy && !a->pointer
&& !a->in_common && !a->use_assoc
&& !(a->function && sym != sym->result))
          || (a->dummy && a->intent == INTENT_OUT && !a->pointer))
        apply_default_init (sym);
    }

In your example, the dummy argument is accessed (attr.referenced) - even though at run time only in very few cases.

Steve, do you see whether the "&& sym->attr.referenced" in the outer loop is required? If yes, why? If not, why does the DT always seems to be properly intialized? Is this dead code? I would understand a "a->referenced" for the non-dummy part inner if-condition to avoid initialization of unused variables.

Tobias


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