Re: [RFC][PATCH] fix casting constant to _Bool

[Dan Carpenter <dan.carpenter@oracle.com>]

On Sat, Jun 16, 2012 at 09:32:50AM -0700, Linus Torvalds wrote:
> On Fri, Jun 15, 2012 at 11:55 PM, Xi Wang <xi.wang@gmail.com> wrote:
> > Casting to _Bool requires a zero test rather than truncation.
> 
> Ack. _Bool is very special (and rather non-C-like).
> 
> > BTW, this patch also disables the warning "cast truncates bits from
> > constant value".  Does that sound good?
> 
> For cast to _Bool, that is correct. Since it doesn't truncate the
> value, the upper bits are not ignored as they are with other casts.
> 

It's pretty rare to see a cast to bool that truncates the value.
My feeling is that most times they are bugs.  I just saw one of
these a couple weeks ago:

http://www.spinics.net/lists/linux-iio/msg05573.html

I wish the error message could be fixed so it says 1 instead of 0.

old: warning: cast truncates bits from constant value (2 becomes 0)
new: warning: cast truncates bits from constant value (2 becomes 1)

regards,
dan carpenter
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