Re: revap types, step 1

[Tobias Schlüter <tobias dot schlueter at physik dot uni-muenchen dot de>]

Steve Kargl wrote:
> On Wed, Aug 25, 2004 at 11:14:44PM -0700, Richard Henderson wrote:
> 
>>+ 
>>+   /* Choose the default double kind.  F2003 merely says that DOUBLE
>>+      PRECISION should be larger than REAL.  Traditionally, DOUBLE
>>+      PRECISION is twice the size of REAL.  We may or may not be able
>>+      to honor either of these constraints, but try our best.  */
> 
> 
> Richard,
> 
> I might be misreading this comment.  Are you saying that
> sizeof(DOUBLE PRECISION) may not be equal to 2*sizeof(REAL)
> with your patch?  This may break a boat load of code that
> uses EQUIVALENCE statements.  OTOH, your patch looks to be
> a major improvement over the previous code.
> 

(Quotes from the draft Fortran 95 standard.)

Just to make clear the requirements of the standard:

WRT precision the standard says this (4.3.1.2, before R412): "The decimal
precision of the double precision real approximation method shall be greater
than that of the default real method."

And under 14.6.3.1:
"In a storage association context

(1) A nonpointer scalar object of type default integer, default real, or
default logical occupies a single numeric storage unit;

(2) A nonpointer scalar object of type double precision real or default
complex occupies two contiguous numeric storage units;

etc."

Note that these requirements are independent, depending on how we layout
equivalences we could be even fulfilling the latter requirement, if we don't
fulfill the former (that is, in the case of -r8; I don't know how we handle
this right now).

- Tobi