🚀 go-pugleaf

In article <478bqi$nb3@rdsunx.crd.ge.com>
           volpe@ausable.crd.ge.com "Christopher R. Volpe" writes:

>In article <815241910snz@soliton.demon.co.uk>, Ian Cargill
> <ian@soliton.demon.co.uk> writes:
>>
>>The standard allows setjmp to be either a macro or an 'identifier 
>>with external linkage'.  Why the latter?   
>
>Why not the latter? Why should an implementer be forced to make setjmp a macro
>rather than an ordinary function call?

Sorry, It was a woefully inadequate question.  I'll do what I should 
have done in the first place and state it in full.

I know a (non-static) function designator would qualify as an identifier 
with external linkage, but if the intention is simply to allow a function, 
why do it this way?

If it is OK to make setjmp a function, why define it as being a macro, 
in 7.6.1.1?  The only other things defined this way are assert, va_arg, 
va_start and va_end, all of which must be macros.  If you want to allow 
it to be either a macro or a function, why use this special wording?
Why not just specify it in the same way as other things which can be 
function and/or macros? (i.e. most functions)  

If 7.6.1.1 refered to 'The setjmp function' instead of 'The setjmp macro', 
7.1.7 would still permit a macro version.  Admittedly, there is a slight 
difference.  In this case, you might want a macro OR a function, but not 
both, but you could cover that with a constraint similar to the one that 
already exists.  i.e. that suppressing a macro definition causes undefined 
behaviour.

I can see why you might want to allow a function call (though it would 
obviously have to be an assembler function that had an intimate knowledge 
of how the compiler worked).  But why do it this way?  I'm curious to 
know why it was done this way, when the standard form of definition, 
together with a suitable constraint, would have done the job.  It is 
sufficiently different from all other function/macro descriptions that 
I thought there must be some Machiavellian reason for doing so. :-)


-- 
Ian