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Re: bug#7928: mktime test in configure: UB resulting in infinite loop
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From: |
Rich Felker |
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Subject: |
Re: bug#7928: mktime test in configure: UB resulting in infinite loop |
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Date: |
Thu, 27 Jan 2011 17:08:46 -0500 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Jan 27, 2011 at 07:42:10PM +0100, Bruno Haible wrote:
> Do you mean to say that GCC produces undefined behaviour for shifts of
> negative values, even those where the result is negative (no overflow)?
> I've never seen a sign of that.
I mean to say that left-shifting a negative value *at all* is
undefined behavior. I doubt gcc will ever break it, but why not use my
version of the code that's 100% safe and never invokes undefined
behavior?
Rich