strtod ("nan") returns negative NaN

[Paul Koning]

> On Aug 15, 2018, at 11:38 AM, Joseph Myers <joseph@codesourcery.com> wrote:
> 
> ...
> 
> * Different processors have different preferences for what a "default" 
> quiet NaN (e.g. one produced by an operation without NaN operands) should 
> look like.  Some clear all the lower mantissa bits, some set them.  If you 
> use the built-in functions then you generate NaNs following GCC's 
> knowledge of such processor conventions.

But does that matter?  It should be sufficient to generate a legal NaN when one is requested.  Given that there are don't care bits in the representation of NaN, it might look different from one generated by the hardware as the output of some operation, but a NaN is a Nan so long as it matches what the spec says -- right?

	paul