Re: Simplify XPath NaN, inf and -0 handling

On Tue, Nov 14, 2017 at 04:23:29PM +0100, Nick Wellnhofer wrote:
> Here's are patch that I'd like to discuss before committing.

   Hi Nick,

  what do you really gain by this ?
Things which were known portable cross many platforms now become unclear again.
Trio might be deprecated, I would ask Daniel Stenberg first, so in copy,

  thanks,

Daniel

> Nick
> 
> ------------------
> 
> https://github.com/nwellnhof/libxml2/commit/8813f397f8925f85ffbe9e9fb62bfaa3c1accf11
> 
> Simplify XPath NaN, inf and -0 handling
> 
> Use C99 macros NAN, INFINITY, isnan, isinf. If they're not available:
> 
> - Assume that (0.0 / 0.0) generates a NaN and !(x == x) tests for NaN.
> - Use C89's HUGE_VAL for INFINITY.
> 
> Remove manual handling of NaN, infinity and negative zero in functions
> xmlXPathValueFlipSign and xmlXPathDivValues.
> 
> Remove xmlXPathGetSign. All the tests for negative zero can be replaced
> with a test for negative or positive zero.
> 
> Simplify xmlXPathRoundFunction.
> 
> Remove Trio dependency.
> 
> This should work on IEEE 754 compliant implementations even if the C99
> macros aren't available, but will likely break some ancient platforms.
> If problems arise, my plan is to port the relevant trionan.c solution
> to xpath.c. Note that non-compliant implementations are impossible
> to fully support, anyway, since XPath requires IEEE 754.
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-- 
Daniel Veillard      | Red Hat Developers Tools http://developer.redhat.com/
[email protected]  | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | virtualization library  http://libvirt.org/