Xref: utzoo comp.sys.amiga.tech:9289 comp.std.c:2359
Newsgroups: comp.sys.amiga.tech,comp.std.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: __chip is evil
Message-ID: <1990Jan13.233457.6002@utzoo.uucp>
Organization: U of Toronto Zoology
References: <85006@linus.UUCP> <4839@sugar.hackercorp.com> <86113@linus.UUCP> <4919@sugar.hackercorp.com>
Date: Sat, 13 Jan 90 23:34:57 GMT

In article <4919@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes:
>> >On the other hand #pragma is not allowed to change the semantics of a
>> >program.
>
>> I'm sorry, but I can't find this in the standard...
>
>Anyone in comp.std.c want to take a crack at it? ...

This is an issue which simply cannot be decided from the text of the
standard.  The usual "not allowed" argument is that the #pragma section
must be read together with the rest of the standard, not in isolation,
and therefore #pragma's "implementation-defined" effect is limited by
the rest of the standard.  The counterargument is that the rest of the
standard must be read together with the #pragma section, i.e. with the
possibility that #pragma may have implementation-defined effects on the
rest of the standard.  Both interpretations are self-consistent, and
there is nothing in the standard that decides between them.

In practice, people *will* implement #pragmas that have semantic effects.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu