Re: [PATCH 1/7] Rework strbuf API and semantics.

From: Jeff King <peff@peff.net>
Date: Sep 6, 2007, 15:36 UTC
Message-ID: <20070906153613.GA4008@coredump.intra.peff.net>
In-Reply-To: <85tzq7bzoz.fsf@lola.goethe.zz>

On Thu, Sep 06, 2007 at 05:06:52PM +0200, David Kastrup wrote:

Show 8 quoted lines

> >   If an object that has automatic storage duration is not initialized
> >   explicitly, its value is indeterminate. If an object that has static
> >   storage duration is not initialized explicitly, then:
> >
> >   -- if it has pointer type, it is initialized to a null pointer;
> 
> That's actually a new one to me.  I don't think that it has been
> always the case in ANSI C.

I don't have the C89 standard, so it's hard to be authoritative. However, according to TCOR1 to the C89 standard, the original text of 6.5.7 contained:

  If an object that has static storage duration is not initialized
  explicitly, it is initialized implicitly as if every member that has
  arithmetic type were assigned 0 and every member that has pointer type
  were assigned a null pointer constant.

and was changed to:

  If an object that has static storage duration is not initialized
  explicitly, then:

    - if it has pointer type, it is initialized to a null pointer;

    - if it has arithmetic type, it is initialized to zero;

    - if it is an aggregate, every member is initialized (recursively)
      according to these rules;

    - if it is a union, the first named member is initialized
      (recursively) according to these rules.

But for the case of pointer initializations, both have the same effect. So I think it has always been the case. Pre-ANSI, who knows. :)

You can find TCOR1 here:

  http://www.open-std.org/jtc1/sc22/wg14/www/docs/tc1.htm

And now I must go get some real work done instead of snooping through standards. :)

-Peff