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Date:      Thu, 19 Aug 1999 17:58:28 +0200
From:      Eivind Eklund <eivind@FreeBSD.org>
To:        Peter Wemm <peter@FreeBSD.org>
Cc:        current@FreeBSD.org
Subject:   NFS HEADS UP (was Re: cvs commit: src/sys/nfs nfsm_subs.h xdr_subs.h)
Message-ID:  <19990819175828.Q45123@bitbox.follo.net>
In-Reply-To: <199908191450.HAA43604@freefall.freebsd.org>; from Peter Wemm on Thu, Aug 19, 1999 at 07:50:13AM -0700
References:  <199908191450.HAA43604@freefall.freebsd.org>

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On Thu, Aug 19, 1999 at 07:50:13AM -0700, Peter Wemm wrote:
> peter       1999/08/19 07:50:13 PDT
> 
>   Modified files:
>     sys/nfs              nfsm_subs.h xdr_subs.h 
>   Log:
>   Convert all the nfs macros to do { blah } while (0) to ensure it
>   works correctly in if/else etc.  egcs had probably picked up most of the
>   problems here before with "ambiguous braces" etc, but this should
>   increase the robustness a bit.  Based on an idea from Eivind Eklund.

When I tested this, I got significant binary changes after changing
the macros to be .  Writing a couple of test programs, I was not able
to get binary changes without actual semantic changes - the optimizer
optimize away do { ... } while(0); just fine.  I didn't have any
testbed for NFS, which was why I didn't commit similar changes myself.

Interpretation: NFS is likely to be different now than it was before
these commits.  This hopefully mean less bugs, but we might also have
had bugs cancelling each other and 'mystery fixes' that no longer
work.  If you get strange effects in NFS in the upcoming time, you
might try flipping this commit.

I still think the change is a good and necessary one.

Eivind.


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