[Cfp-interest 2746] {FLT, DBL, LDBL}_IS_IEC_60559 macros: clarification needed

[Vincent Lefevre]

N3096 says in 5.2.4.2.2p18:

  Whether a type has the same precision (p) and exponent range
  (emin ≤ e ≤ emax) as an IEC 60559 format is characterized by
  the implementation-defined values of FLT_IS_IEC_60559,
  DBL_IS_IEC_60559 and LDBL_IS_IEC_60559 (this does not imply
  conformance to Annex F):
  [...]

So, this does not concern whether zero is signed and the existence of
subnormals, infinities and NaN. For instance, FLT_IS_IEC_60559 may be
equal to 1 while INFINITY and NAN are not defined. Is this OK? In any
case, this should be clarified, because the name of the macros could
be misleading.

Moreover, since the radix also matters, the text should also say
"same radix".

And what is meant exactly by "an IEC 60559 format"?
An interchange format? Or just a basic format? I suppose that
extended precision formats and extendable precision formats
are excluded.

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Vincent Lefèvre <vincent at vinc17.net> - Web: <https://www.vinc17.net/>
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