Re: new modules *printf-gnu

[Bruno Haible]

Hi Eric,

Thanks for the pointers.

> The latest draft comments on C go a step further (warning, big document):
> https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3091.doc

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3108.doc
seems to be the latest one, now.

> Searching that for %B finds:
> FR-217
> Make %B optional
> Accepted with comment: Wording from N 3072 section 15 with editorial 
> corrections
> 
> so now go check N3072:
> https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3072.htm#make-printf-format-specifier-b-optional
> 
> which states that the PRIBPTR in <inttypes.h> is now a reliable witness
> of whether %B has C23 semantics rather than other
> implementation-defined semantics.
> 
> and glibc has updated their %B implementation accordingly:
> https://sourceware.org/git/?p=glibc.git;a=commit;h=2d4728e60621

The implementation could be to define a C macro or AC_SUBSTed variable in
  gl_PREREQ_VASNPRINTF_DIRECTIVE_UPPERCASE_B
and test it in inttypes.in.h.

But still, I don't wish to make this change to Gnulib's <inttypes.h> for the
moment, because:
  * Logically, there should also be definitions of
      PRIbN PRIbLEASTN PRIbFASTN PRIbMAX PRIbPTR
    in <inttypes.h>, but I do not see them in the latest complete PDF
    https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3088.pdf
    section 7.8.1.(3).
  * These macros are redundant anyway:
      PRIb8        "w8b"
      PRIb16       "w16b"
      PRIb32       "w32b"
      PRIb64       "w64b"
      PRIbLEAST8   "w8b"
      PRIbLEAST16  "w16b"
      PRIbLEAST32  "w32b"
      PRIbLEAST64  "w64b"
      PRIbFAST8    "wf8b"
      PRIbFAST16   "wf16b"
      PRIbFAST32   "wf32b"
      PRIbFAST64   "wf64b"
      PRIbMAX      "jb"
    and likewise for uppercase B.

Bruno