Re: com php-src: fix negating an unsigned: Zend/zend_operators.h

Hi Nikita, On Mon, September 15, 2014 22:02, Nikita Popov wrote: > On Mon, Sep 15, 2014 at 7:46 PM, Anatol Belski <ab@php.net> wrote: > > >> Commit: e0ff5238c5d744509f93aaf914e23f17d51c5ae3 >> Author: Anatol Belski <ab@php.net> Mon, 15 Sep 2014 17:48:15 >> +0200 >> Parents: 383a0773ff27cf57b94fe11d2f825b00cff88714 >> Branches: master >> >> >> Link: >> >> http://git.php.net/?p=php-src.git;a=commitdiff;h=e0ff5238c5d744509f93aaf >> 914e23f17d51c5ae3 >> >> >> Log: >> fix negating an unsigned >> >> Changed paths: >> M Zend/zend_operators.h >> >> >> >> Diff: >> diff --git a/Zend/zend_operators.h b/Zend/zend_operators.h index >> 41342de..a50e65d 100644 >> --- a/Zend/zend_operators.h >> +++ b/Zend/zend_operators.h >> @@ -1036,7 +1036,7 @@ static zend_always_inline void >> fast_is_not_identical_function(zval *result, zval /* buf points to the >> END of the buffer */ >> #define _zend_print_signed_to_buf(buf, num, vartype, result) do { >> \ >> if (num < 0) { \ >> - _zend_print_unsigned_to_buf((buf), -(vartype)(num), vartype, >> (result)); \ >> + _zend_print_unsigned_to_buf((buf), (~((vartype)(num)) + 1), >> vartype, (result)); \ *--(result) = '-'; >> \ >> } else { >> \ >> _zend_print_unsigned_to_buf((buf), (num), vartype, (result)); >> \ >> >> > > Why this change? Unary minus of an unsigned value is a well-defined > operation, see C89 3.1.2.5c5 or C99 6.2.5c9. Writing it this way seems > much less clear to me. Unary minus is the operation that we mean here > semantically. > > Nikita This change is nothing than fixing this warning http://msdn.microsoft.com/en-us/library/4kh09110.aspx -x does the same as (~x + 1), so technically no issue. Hopefully no big issue for PHP as it's hidden behind the internal implementation. I wouldn't touch it but for the warning fix, maybe one can wrap it somehow. Actually thinking about a small set of wrappers to compare or do maths with signed/unsigned safer and warning free. Regards Anatol