Read and print NaN significand if <ieee754.h>

* configure.ac: Check for ieee754.h.
* doc/lispref/numbers.texi (Float Basics): Document
that NaN string representation digits are machine-dependent.
* etc/NEWS: Mention the change.
* src/lread.c, src/print.c [HAVE_IEEE754_H]: Include ieee754.h.
* src/lread.c (string_to_number) [HAVE_IEEE754_H]:
* src/print.c (float_to_string) [HAVE_IEEE754_H]:
Read and print NaN significand.

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/lispref/numbers.texi b/doc/lispref/numbers.texi
index 14d5059ffb3..a3317c9a260 100644
--- a/doc/lispref/numbers.texi
+++ b/doc/lispref/numbers.texi
@@ -241,7 +241,7 @@ A NaN is never numerically equal to any value, not even to itself.
 NaNs carry a sign and a significand, and non-numeric functions treat
 two NaNs as equal when their
 signs and significands agree.  Significands of NaNs are
-machine-dependent and are not directly visible to Emacs Lisp.
+machine-dependent, as are the digits in their string representation.
 
   When NaNs and signed zeros are involved, non-numeric functions like
 @code{eql}, @code{equal}, @code{sxhash-eql}, @code{sxhash-equal} and