[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-ppc] [PATCH 3/3] maint: Fix macros with broken 'do/while(0); '

From: David Gibson
Subject: Re: [Qemu-ppc] [PATCH 3/3] maint: Fix macros with broken 'do/while(0); ' usage
Date: Mon, 4 Dec 2017 11:45:26 +1100
User-agent: Mutt/1.9.1 (2017-09-22)

On Thu, Nov 30, 2017 at 07:41:59AM -0600, Eric Blake wrote:
> The point of writing a macro embedded in a 'do { ... } while (0)'
> loop is so that the macro can be used as a drop-in statement with
> the caller supplying the trailing ';'.  Although our coding style
> frowns on brace-less 'if':
>   if (cond)
>     statement;
>   else
>     something else;
> the use of do/while (0) in a macro is absolutely essential for the
> purpose of avoiding a syntax error on the 'else' - but it only works
> if there is no trailing ';' in the macro (as the ';' in the code
> calling the macro would then be a second statement and cause the
> 'else' to not pair to the 'if').
> Many of the places touched in this code are examples of the ugly
> bit-rotting debug print statements; cleaning those up is left as
> a bite-sized task for another day.
> Found mechanically via: $ git grep -B1 'while (0);' | grep -A1 \\\\
> Signed-off-by: Eric Blake <address@hidden>

ppc related portions

Acked-by: David Gibson <address@hidden>

David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!

Attachment: signature.asc
Description: PGP signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]