linux-kernel - Re: macros: "do-while" versus "({ })" and a compile-time error

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <45A3D1DF.4020205@s5r6.in-berlin.de>
Date:	Tue, 09 Jan 2007 18:33:19 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	"Robert P. J. Day" <rpjday@...dspring.com>
CC:	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: macros:  "do-while" versus "({ })" and a compile-time error

Robert P. J. Day wrote:
>   just to stir the pot a bit regarding the discussion of the two
> different ways to define macros,

You mean function-like macros, right?

> i've just noticed that the "({ })"
> notation is not universally acceptable.  i've seen examples where
> using that notation causes gcc to produce:
> 
>   error: braced-group within expression allowed only inside a function

And function calls and macros which expand to "do { expr; } while (0)"
won't work anywhere outside of functions either.

> i wasn't aware that there were limits on this notation.  can someone
> clarify this?  under what circumstances *can't* you use that notation?
> thanks.

The limitations are certainly highly compiler-specific.
-- 
Stefan Richter
-=====-=-=== ---= -=--=
http://arcgraph.de/sr/
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/