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Path: utzoo!linus!security!genrad!decvax!bbncca!keesan
From: keesan@bbncca.ARPA (Morris Keesan)
Newsgroups: net.lang.c
Subject: Re: storage class ambiguity
Message-ID: <249@bbncca.ARPA>
Date: Wed, 2-Nov-83 16:03:03 EST
Article-I.D.: bbncca.249
Posted: Wed Nov  2 16:03:03 1983
Date-Received: Sun, 6-Nov-83 06:40:39 EST
References: <3610@genrad.UUCP>
Organization: Bolt, Beranek and Newman, Cambridge, Ma.
Lines: 58

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This note is to disagree strongly with John Nelson (genrad!john).
I quote alternately from his message and the "C Reference Manual", 
Appendix A of "The C Programming Language", which I take to be the
final arbiter of what is and isn't "strictly C".

Nelson:
-------
>		 file 1: extern int foo;
>		 file 2: extern int foo;
>
>This should not generate a loader error, The loader is SUPPOSED to
>allocate storage for foo.
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The loader is NOT supposed to allocate storage, as  per
Kernighan and Ritchie, p. 206:
-----------------------------
 The appearance of the extern keyword in an external definition indicates
 that storage for the identifiers being declared will be allocated in another
 file.  Thus in a multi-file program, an external data definition without the
 extern specifier must appear in exactly one of the files.
-----------

Nelson:
-------
>		 file 1: extern int foo = 8;
>
>If the compiler generates an error on this, then it is just plain WRONG!
>I cannot emphasize this enough.  The problem is not that the reference
>manual should not say that extern is the default storage class, it IS,
>and any compiler that does not work this way is not strictly C!
-----------
When the compiler generates an error on the above, it is behaving RIGHT,
as evidenced by the sentence in Kernighan & Ritchie immediately following
the previous citation.
Kernighan and Ritchie, also p. 206:
-----------------------------------
 The identifier can be initialized only in the declaration where storage is
 allocated.
----------

Nelson:
-------
>I had a similar problem with the Whitesmith compiler - all externs had to
>be initialized (which could be lived with) but also, static's had to be
>initialized!  If you have:
>
>		 file 1: static int foo;
>
>you get the compiler message: "undeclared static foo".  We don't use
>Whitesmiths anymore for this and numerous other non-standard items.
----------

Here I share John Nelson's complaint.  The C compiler for Charles River
Data Systems' UNOS system also requires explicit initialization of statics,
in direct violation of Kernighan & Ritchie, p. 198: "Static and external
variables which are not initialized are guaranteed to start off as 0;"