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From: rusty@rustcorp.com.au (Rusty Russell)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] serial/atmel_serial: Fix another fallout of the change to BUILD_BUG_ON
Date: Tue, 20 Oct 2009 01:02:29 +1030	[thread overview]
Message-ID: <200910200102.30478.rusty@rustcorp.com.au> (raw)
In-Reply-To: <4ADC3D3C020000780001AA10@vpn.id2.novell.com>

On Mon, 19 Oct 2009 06:49:40 pm Jan Beulich wrote:
> >>> Rusty Russell <rusty@rustcorp.com.au> 19.10.09 08:08 >>>
> >How's this?  It's not quite valid C, but it "works":
> 
> But that's not what you proposed initially, i.e. generating a link time
> error if a compile time error can't be generated (and only if even a link
> time error isn't possible, a run time one should be forced).

Yeah, this was cleverer.  A compile time is nicer than link time.  And this
is *actually* what I want: a compile fail if the compiler knows enough, runtime
otherwise.

> And btw., why do you think this isn't valid C?

>From my glance at ISO C, non-positive sized variable length arrays are
invalid.  gcc here seems to give the expected results (eg. sizeof gives
a negative result).

Cheers,
Rusty.

WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: "Jan Beulich" <JBeulich@novell.com>
Cc: "Haavard Skinnemoen" <haavard.skinnemoen@atmel.com>,
	"Haavard Skinnemoen" <hskinnemoen@atmel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Alan Cox" <alan@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org,
	u.kleine-koenig@pengutronix.de, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] serial/atmel_serial: Fix another fallout of the change to BUILD_BUG_ON
Date: Tue, 20 Oct 2009 01:02:29 +1030	[thread overview]
Message-ID: <200910200102.30478.rusty@rustcorp.com.au> (raw)
In-Reply-To: <4ADC3D3C020000780001AA10@vpn.id2.novell.com>

On Mon, 19 Oct 2009 06:49:40 pm Jan Beulich wrote:
> >>> Rusty Russell <rusty@rustcorp.com.au> 19.10.09 08:08 >>>
> >How's this?  It's not quite valid C, but it "works":
> 
> But that's not what you proposed initially, i.e. generating a link time
> error if a compile time error can't be generated (and only if even a link
> time error isn't possible, a run time one should be forced).

Yeah, this was cleverer.  A compile time is nicer than link time.  And this
is *actually* what I want: a compile fail if the compiler knows enough, runtime
otherwise.

> And btw., why do you think this isn't valid C?

>From my glance at ISO C, non-positive sized variable length arrays are
invalid.  gcc here seems to give the expected results (eg. sizeof gives
a negative result).

Cheers,
Rusty.

  reply	other threads:[~2009-10-19 14:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-13  7:08 [PATCH] serial/atmel_serial: Fix another fallout of the change to BUILD_BUG_ON Uwe Kleine-König
2009-10-13  7:08 ` Uwe Kleine-König
2009-10-13  7:26 ` Haavard Skinnemoen
2009-10-13  7:26   ` Haavard Skinnemoen
2009-10-13  7:40   ` Jan Beulich
2009-10-13  7:40     ` Jan Beulich
2009-10-19  6:08     ` Rusty Russell
2009-10-19  6:08       ` Rusty Russell
2009-10-19  8:19       ` Jan Beulich
2009-10-19  8:19         ` Jan Beulich
2009-10-19 14:32         ` Rusty Russell [this message]
2009-10-19 14:32           ` Rusty Russell
2009-10-13  8:24   ` Uwe Kleine-König
2009-10-13  8:24     ` Uwe Kleine-König
2009-10-21 12:27     ` Russell King - ARM Linux
2009-10-21 12:27       ` Russell King - ARM Linux
2009-10-21 13:56       ` Uwe Kleine-König
2009-10-21 13:56         ` Uwe Kleine-König

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