Re: [PATCH] PR fortran/83998 -- fix dot_product on 0-sized arrays

[Steve Kargl <sgk at troutmask dot apl dot washington dot edu>]

On Thu, Jan 25, 2018 at 07:06:10AM -0800, Steve Kargl wrote:
> On Thu, Jan 25, 2018 at 08:37:54AM +0100, Thomas Koenig wrote:
> > 
> > Second, why do you remove this
> > 
> > > -  temp.value.op.op = INTRINSIC_NONE;
> > > -  temp.value.op.op1 = vector_a;
> > > -  temp.value.op.op2 = vector_b;
> > > -  gfc_type_convert_binary (&temp, 1);
> > 
> > block of code?
> 
> It is dead code.  temp is set to the typespec of 
> the mixed-mode math result, but it is never used.
> compute_dot_product does the mixed-mode math,
> because it uses gfc_add() from arith.c.
> 

Upon re-reading gfc_type_convert_binary, it isn't dead.
It simply isn't needed, because gfc_add() eventually
lands at arith.c (eval_intrinsics):

    /* Numeric binary  */
    case INTRINSIC_PLUS:
    case INTRINSIC_MINUS:
    case INTRINSIC_TIMES:
    case INTRINSIC_DIVIDE:
    case INTRINSIC_POWER:
      if (!gfc_numeric_ts (&op1->ts) || !gfc_numeric_ts (&op2->ts))
	goto runtime;

      /* Insert any necessary type conversions to make the operands
	 compatible.  */

      temp.expr_type = EXPR_OP;
      gfc_clear_ts (&temp.ts);
      temp.value.op.op = op;

      temp.value.op.op1 = op1;
      temp.value.op.op2 = op2;

      gfc_type_convert_binary (&temp, warn_conversion || warn_conversion_extra);

-- 
Steve