[patch, fortran] Fix PR29458 - spurious warning for implied do-loop counter

[Daniel Franke]

This code gives a warning about 'i' being used uninitialized:

  integer :: n, i
  n = 5
  n = SUM((/(i,i=1,n)/))
end

Attached patch fixes this by shadowing 'i' with a temporary variable. Further, 
it wraps the implied-do in its own block instead of placing it in the parent 
block directly. The relevant part now looks like this, 'i' is never touched:

    {                         
      shadow_loopvar.4 = 1;
      D.1515 = n;
      [...]
      while (1)
        {
          if (shadow_loopvar.4 > D.1515) goto L.1;
          (*(integer(kind=4)[0] *) atmp.2.data)[offset.3] = shadow_loopvar.4;
          offset.3 = offset.3 + 1;
          shadow_loopvar.4 = shadow_loopvar.4 + 1;
        }
      L.1:;
    }


2009-04-05  Daniel Franke  <franke.daniel@gmail.com>

	PR fortran/29458
	* trans-array.c (gfc_trans_array_constructor_value): Shadow implied
	do-loop variable to avoid spurious middle-end warnings.

2009-04-05  Daniel Franke  <franke.daniel@gmail.com>

	PR fortran/29458
	* gfortran.dg/implied_do_1.f90: New.


Regression tested on i686-pc-linux-gnu.
Ok for trunk (and maybe 4.4.1)?

Cheers

	Daniel

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