🚀 go-pugleaf

In article <4hn3mg$c9v@info1.sdrc.com>, larry.jones@sdrc.com (Larry Jones) writes:
# (quoting the standard):
# The expression that specifies the width of a bit-field shall be
# an integral constant expression that nas nonnegative value that
# shall not exceed the number of bits in an ordinary object of
# compatible type.
#
>In article <uYgPxQ9ytt9W084yn@csn.net>, thads@csn.net (Thad Smith) writes:
>> What does "ordinary object of compatible type" mean?  Could that mean
>> long?  I now think that an implementation could allow specification of
>> a number of bits greater than int, but less than or equal to bits in
>> long.  To access the value, the programmer casts the bit-field to long
>> or unsigned long.  The cast would preceed the integral promotion, I
>> think, and allow access to the longer value.

>An ordinary object (i.e., not a bit-field) with the same type as the
>declared type of the bit-field which is required to be int, signed int,
>or unsigned int.  As Norm Diamond pointed out, that requirement is in
>semantics, not constraints, so an implementation is free to add an
>extension allowing other types (like long), and some do.

Although I'm missing half the postings in this thread, everything sounds
right so far.

>Such implementations presumably extend the integral promotion rules in
>the obvious fashion as well in order to eliminate the need for casts.

They cannot.  As Thad Smith's original posting pointed out, the standard
prohibits this extension.  And as Mr. Smith's later posting points out,
as quoted above, a cast could do it.  In order to permit implementations
to provide this further extension without requiring casts, it would be
necessary to revise the wording in ANSI Classic section 3.2.1.1, page 35
lines 12 to 15.  These lines (originally quoted my Mr. Smith) currently
force the bit-field value into an int or unsigned int regardless.
--
 <<  If this were the company's opinion, I would not be allowed to post it.  >>
"I paid money for this car, I pay taxes for vehicle registration and a driver's
license, so I can drive in any lane I want, and no innocent victim gets to call
the cops just 'cause the lane's not goin' the same direction as me" - J Spammer