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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH] [TRIVIAL] usb-linux: remove unreachable
	default in switch statement
Date: Wed, 17 Mar 2010 17:43:06 +0000
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	<201003171708.04633.paul@codesourcery.com>
	<4BA10E49.90703@codemonkey.ws>
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Paul Bolle <pebolle@tiscali.nl>, qemu-devel@nongnu.org

> > If something should never happen (as in this case) then an abort/assert
> > is completely appropriate. Once things get that screwed up there's no
> > right answer, and the best thing we can do is terminate immediately to
> > try and avoid further damage.
> 
> This case was:
> 
> switch (foo & 0x03) {
> case 0: case 1: case 2: case 3:
> default:
> }
> 
> The default is unreachable.  Having it there just introduces more code
> that serves no purpose.  Unless someone does something totally foolish
> and changes the mask in the switch statement, there's no way it will
> ever be reachable.

I mistakenly remembered this was using a symbolic mask rather than a literal 
0x03. In that case I'd argue it's much easier to make the dumb error you 
describe, and the assert can be a handy cluebat.

I guess it's largely personal preference - I prefer to add the default case to 
make it clear that falling through is never gong to be the right answer.

Paul