[Cfp-interest 1712] WG14 IEEE 754-C binding meeting minutes 2020/07/22

[Rajan Bhakta]

  Attendees: Rajan, Jim, David O., Fred, Mike, Ian, David H.

  New agenda items:
    None.

  Carry over action items:
    Jim: Check WANT macro issue in CFP 1581 - Done.

  Last meeting action items:
    All: Need ideas on how to convert Word to good PDF with links. Jim: 
Add hex to annex draft. - Done.
    Fred: Write paper saying ‘const’ missing in *payload. - Done.
    Jim: Rewrite CFP 1643: Rnd ties away issue. - Done.
    Jim+Fred: Re no prototype vs varargs prototype, find where in C where 
float is promoted to double. - Done.

  New action items:
    Jim: Create a proposal based on CFP 1709 updates to Annex B with the 
addition of N and M parameter descriptions.
    Jim: For cfp3x-annex-20200706.pdf, Annex X, new example (page 33), 
change the magic number 40 (which needs to be verified) to be a macro and 
add in a descriptive definition of that macro.
    Jim: For cfp3x-annex-20200706.pdf, Annex X, strtoencdecd* function 
declarations (page 35), make the pointers into arrays to allow giving a 
size for the array. 
    Fred: Submit the paper in CFP 1703 to WG14 as a CFP paper.
    Jim: Submit CFP 1653's changes (appropriately colorized or changed to 
highlight the changes) to WG14.
    Jim: Put CFP 1634 (with the correction: 'prototype is extended' -> 
'prototype is expanded') into TS3 as an annex.
    Fred: Submit CFP 1704 to WG14 as a proposal from CFP.
    Jim: Prepare a suggested change to C2X proposal based on CFP 1687 
option 3.
    Fred: Submit CFP 1702 to WG14 as a CFP paper.
    David H: Come up with a sentence to add to footnote 295 (as per CFP 
1697) to point out the possible numerical differences in output.

  Next Meeting(s):
    Wednesday, August 19th, 2020, 11:00 EST, 8:00 PST, 4PM UTC
    ISO Zoom teleconference
    Please notify the group if this time slot does not work.
 
  C++ liaison
    C/C++ compatibility for extensions floating types
    See [Cfp-interest 1638, 1701] C++ floating-point work David Olsen
      Difference between C++ and our TS in determination of types. C++ 
picks standard types whereas we pick the interchange types. It was an 
issue for the tgmath functions before the rework (Ex. Functions that round 
to narrower type).
      In C++ you can have these new IEEE types and non-IEEE standard 
types.
 
  C2X Integration:
    Latest C2X draft: 
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2478.pdf
    Part 1
    Part 2
    Part 3
    Part 4ab
    Part 5abcd
    IEEE 754-2019 support

  Action item details
    Jim: Check WANT macro issue in [CFP 1581]
      Some of the macros are missing in N2478 as well.
      Rajan: Add in some text to describe what N and M are.
      Resolve as per CFP 1709.
      *AI*: Jim: Create a proposal based on CFP 1709 updates to Annex B 
with the addition of N and M parameter descriptions.

    All: Need ideas on how to convert Word to good PDF with links.
      Adobe's online version does not work. The old Adobe Pro 9 works on 
PC. Jim to try on Mac (has been ordered).

    Jim: Add hex to annex draft [CFP 1684]
      New example added (page 33).
      Mike: Don't like seeing the "40" constant in the example.
        Jim: Wasn't there a macro added for the maximum size Fred?
        Fred: I don't think so.
        Rajan: Do a "#define MAX_VALUE 40 // Max hex digits" and use that 
in the declaration and strfromenc call.
      Resolve as per CFP 1692.
      *AI*: Jim: For cfp3x-annex-20200706.pdf, Annex X, new example (page 
33), change the magic number 40 (review if this is big enough) to be a 
macro and add in a descriptive definition of that macro.
      *AI*: Jim: For cfp3x-annex-20200706.pdf, Annex X, strtoencdecd* 
function declarations (page 35), make the pointers into arrays to allow 
giving a size for the array.
 
    Fred: Write paper saying ‘const’ missing in *payload [CFP 1655]
      See CFP 1703.
      *AI*: Fred to submit the paper in CFP 1703 to WG14 as a CFP paper.

    Jim: Rewrite CFP 1643: Rnd ties away issue.
      See CFP 1653.
      *AI*: Jim: Submit CFP 1653's changes (appropriately colorized or 
changed to highlight the changes) to WG14.

    Jim+Fred: Re no prototype vs varargs prototype, find where in C where 
float is promoted to double
      See CFP 1688.
      Fred: This is a change to the standard.
        Jim: No, this is a change to the TS3 annex as per CFP 1634 (with 
the correction: 'prototype is extended' -> 'prototype is expanded').
      *AI*: Jim: Put CFP 1634 (with the correction: 'prototype is 
extended' -> 'prototype is expanded') into TS3 as an annex.

  Other issues
    Constant expressions evaluated in translation environment [CFP 1579]
      See CFP 1704.
      *AI*: Fred: Submit CFP 1704 to WG14 as a proposal from CFP.

    WANT macros for Annex F interfaces [CFP 1627]
      See CFP 1687.
      Option 1 is editorial, while 2 and 3 are changes.
      Most seem to prefer option 3.
      Suggested change to C2X.
      *AI*: Jim: Prepare a suggested change to C2X proposal based on CFP 
1687 option 3.

    WANT macros for decimal and math functions [CFP 1657]
      See CFP 1707.
      Fred: Current version of Annex X has the 
__STDC_WANT_IEC_60559_TYPES_EXT__ want macro in it.
      Fred: Withdrawing my issue.

    intmax_t removal [CFP 1617]
      See CFP 1702.
      Jim: The naming in the compoundn functions is different from other 
functions like scalbn and scalbln to reflect the long argument.
      Rajan: The change in return value from unspecified value to NaN may 
cause questions.
      *AI*: Fred: Submit CFP 1702 to WG14 as a CFP paper.

    %a with formatting precision [CFP 1693]
      See CFP 1700.
      Ian: Should we be making a recommendation instead of a requirement?
      Fred: Required to be correctly rounded.
      Jim: Only within the possible representable set of values.
        We could add a note that is essentially a warning.
      David H: For portable code, they shouldn't get close to this case.
      Jim: We could disallow a formatting precision of zero.
      David H: That would be different from Decimal.
      Fred: The problem is this applies to any precision lower than the 
full precision needed for the value.
      Jim: Different implementations can give different results. So not 
portable.
      Fred: Even with %a trailing zeros can be trimmed so not portable.
      Ian: What is this useful for?
        Jim: For showing what is in memory.
      David H: If the conversion is less than full precision, the leading 
digit has to be between 8-F.
      Jim: Are we agreed we need a note about this?
      David H: For precisions less than full, the choice of a leading 
digit can differ between implementations.
      Jim/David H: We should point out the numerical difference in the 
output by expanding the footnote.
      *AI*: David H: Come up with a sentence to add to footnote 295 (as 
per CFP 1697) to point out the possible numerical differences in output.

    Triple (1,0,0) [CFP 1675]
      Discuss next meeting.


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