Xref: utzoo comp.lang.c:20241 comp.std.c:1451
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From: mcdaniel@uicsrd.csrd.uiuc.edu (Tim McDaniel)
Newsgroups: comp.lang.c,comp.std.c
Subject: Re: Misdeclaring "main"
Message-ID: <1612@garcon.cso.uiuc.edu>
Date: 29 Jul 89 06:02:18 GMT
References: <28398@beta.lanl.gov> <14020068@hpisod2.HP.COM> <2268@auspex.auspex.com> <13104@bloom-beacon.MIT.EDU>
Sender: news@garcon.cso.uiuc.edu
Reply-To: mcdaniel@uicsrd.csrd.uiuc.edu (Tim McDaniel)
Followup-To: comp.std.c
Organization: Center for Supercomputing R&D (Cedar), U. of Ill.
Lines: 54

This is cross-posted to comp.lang.c (original article's newsgroup) and
comp.std.c (I have standards questions).  Followups have been
redirected to comp.std.c.

In article <13104@bloom-beacon.MIT.EDU> scs@adam.pika.mit.edu (Steve
Summit) writes:
>The production
>
>	struct { struct-decl-list } id (arg-list) decl-list compound-statement
>
>yields a function that cannot be (correctly) called, since no
>other object can be declared with a type-equivalent structure.

I'm not so sure.  Separate compilation is allowed in C, but struct
tags (and their definitions) are not global in scope; for external
linkage, only the types and order of the struct's members matter.
I would think the following declarations are strictly conforming:

in foo.c:
        extern struct { int f1; float f2; } func(); ...

in bar.c:
        struct { int a6; float whacky; } func() ...

However, K&R 2, 1st edition, p. 213 says

     A structure or union specifier with a list but no tag creates a
     unique type; it can referred to directly only in the declaration
     of which it is a part.

>The production
>
>	struct tag { struct-decl-list } id (arg-list) ...
>
>yields a function that can only be called by routines appearing
>later in the same file.

This statement is even more problematical.  How does it differ from
	struct tag { struct-decl-list };
        struct tag id (arg-list) ...
?  If there is no difference, the "struct tag" declaration could just
as easily be in an include file, and another file could include it and
declare
        extern struct tag id ();
Surely *this* behavior is blessed by the standard.

--
"Let me control a planet's oxygen supply, and I don't care who makes
the laws." - GREAT CTHUHLU'S STARRY WISDOM BAND (via Roger Leroux)
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