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bug#766: 23.0.60; interesting warning during compilation
From: |
Stefan Monnier |
Subject: |
bug#766: 23.0.60; interesting warning during compilation |
Date: |
Wed, 03 Sep 2008 14:47:14 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) |
>> > If someone has suggestions how to avoid this warning without making
>> > code ugly and unreadable, and preferably without system-dependent
>> > #ifdef's, I'm all ears.
>>
>> EMACS_INT high_ino = s.st_ino >> 31 >> 1;
> Thanks. Can we be reasonably sure that GCC will not become smart
> enough some day to flag this as well?
I don't think anybody can guarantee it, but usually it's a bad idea to
output warnings about post-optimization code, so you may hope that GCC
will optimize "x >> 31 >> 1" to "x >> 32" without ever outputing
a warning about the silliness of the end result.
Then again, the present code shows that even outputting a warning about
"x >> 32" is already borderline annoying, so there's no guarantee gcc
won't become more annoying in the future.
Stefan
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Stefan Monnier <=