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From: guido@cwi.nl (Guido van Rossum)
Newsgroups: comp.lang.c,comp.std.c
Subject: Re: union *func()
Message-ID: <7689@boring.cwi.nl>
Date: 31 Oct 88 12:43:52 GMT
References: <2205@arcturus> <14172@mimsy.UUCP> <1585@solo8.cs.vu.nl> <14201@mimsy.UUCP> <7686@boring.cwi.nl>
Sender: news@cwi.nl
Reply-To: guido@cwi.nl (Guido van Rossum)
Organization: The Royal Society for Prevention of Cruelty to Amoebae
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In article <7686@boring.cwi.nl> I wrote:
>Chris's original posting said that "v = func().a" is legal, unless a is
>an array.  The reason was that C has no array assignment, not that
>there's anything special with array members of structs returned by
>functions.  A less confusing way to state the rules is that "func().a" is
>legal, but as an rvalue only.

I received a mail message stating that in fact *any* use of func().a is
illegal when a is an array member; the reason being that this use of an
array name requires conversion to a pointer to its first element, and of
course Chris has adequately explained why that should be illegal.

I suppose that it is thus even illegal to write something like
"v = func().a[0]", even though that would make perfect sense (all
Chris's examples showed cases where a's address or the address of some
element was actually saved).  I suppose it would be possible to change
various rules about pointers, arrays, rvalues and lvalues to fix this,
but nobody cared.
--
Guido van Rossum, Centre for Mathematics and Computer Science (CWI), Amsterdam
guido@piring.cwi.nl or mcvax!piring!guido or guido%piring.cwi.nl@uunet.uu.net