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Date: Wed, 17 Mar 2010 22:15:33 +0200
Message-ID: <f43fc5581003171315g7e14afdat2c31d54bb1d42bd0@mail.gmail.com>
Subject: Re: [Qemu-devel] [PATCH] [TRIVIAL] usb-linux: remove unreachable
	default in switch statement
From: Blue Swirl <blauwirbel@gmail.com>
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To: Paul Brook <paul@codesourcery.com>
Cc: Paul Bolle <pebolle@tiscali.nl>, qemu-devel@nongnu.org

On 3/17/10, Paul Brook <paul@codesourcery.com> wrote:
> > > 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.

This breaks build (gcc 4.3.2):
  CC    usb-linux.o
cc1: warnings being treated as errors
/src/qemu/usb-linux.c: In function 'usb_linux_update_endp_table':
/src/qemu/usb-linux.c:759: error: 'type' may be used uninitialized in
this function