Misdeclaring "main"

[Tim McDaniel]

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 at bloom-beacon.MIT.EDU> scs at 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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