Re: [PATCH] Fortran: fix CLASS attribute handling [PR106856]

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

On Fri, Mar 03, 2023 at 10:24:07PM +0100, Mikael Morin wrote:
> Hello,
> 
> Le 03/03/2023 à 20:57, Steve Kargl via Fortran a écrit :
> > On Thu, Mar 02, 2023 at 11:03:48PM +0100, Harald Anlauf via Fortran wrote:
> > > -  if (attr->class_ok)
> > > -    /* Class container has already been built.  */
> > > +  /* Class container has already been built with same name.  */
> > > +  if (attr->class_ok
> > > +      && ts->u.derived->components->attr.dimension >= attr->dimension
> > > +      && ts->u.derived->components->attr.codimension >= attr->codimension
> > > +      && ts->u.derived->components->attr.class_pointer >= attr->pointer
> > > +      && ts->u.derived->components->attr.allocatable >= attr->allocatable)
> > 
> > I suppose I'm a bit confused here.  dimension, codimension,
> > pointer and allocatable are 1-bit bitfields in the attr
> > struct.  These can have the values 0 and 1, so the above
> > conditionals are always true.
> > 
> as I understand it, they aren't if attr has attributes that aren't already
> set in the class container's first component.
> a >= b == !(a < b) and if a and b are boolean-valued, a < b == !a && b.
> Admittedly, I haven't tested the logic like Harald has.
> 

Mikael, thanks for smacking me with the clue stick.  I had to do a quick
test to see the trees.

% cc -o z a.c && ./z
a.i = 0,  b.i = 0, a.i >= b.i = 1
a.i = 1,  b.i = 0, a.i >= b.i = 1
a.i = 1,  b.i = 1, a.i >= b.i = 1
a.i = 0,  b.i = 1, a.i >= b.i = 0

I was overlooking the last case.  So, the above is an all
or nothing test.

-- 
steve