Re: [RFC PATCH]: autom4te: report subsecond timestamp support in --version

[Jacob Bachmeyer]

Zack Weinberg wrote:
> On Mon, Dec 4, 2023, at 7:26 PM, Jacob Bachmeyer wrote:
>   
> > Now that I have seen the actual patch, yes, this test should be
> > accurate.  The test in the main autom4te script will also work, even
> > if there is a mismatch between the script and its library
> >     
>
> Good.
>
>   
> > This appears to be misaligned with the GNU Coding Standards, which
> > states:  "The first line is meant to be easy for a program to parse;
> > the version number proper starts after the last space."
> >
> > Perhaps the best option would be to conditionally add a line "This
> > autom4te supports subsecond timestamps." after the license notice?
> >     
>
> I don't like putting anything after the license notice because it's
> convenient to be able to pipe --version output to sed '/Copyright/,$d'
> without losing anything relevant for troubleshooting.  So how about
>
> $ autom4te --version
> autom4te (GNU Autoconf) 2.71
> Features: subsecond-timestamps
>
> Copyright (C) 2021 Free Software Foundation, Inc.
> License GPLv3+/Autoconf: GNU GPL version 3 or later
> <https://gnu.org/licenses/gpl.html>, <https://gnu.org/licenses/exceptions.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.
>
> Written by Akim Demaille.
>
> This preserves the effectiveness of sed '/Copyright/,$d' and also
> leaves room for future additions to the "Features:" line.

That looks like a good idea to me, although the GNU Coding Standards do 
say (section 4.8.1, "--version") that the copyright and license notices 
"should" immediately follow the version numbers.  The presence or 
absence of this feature is effectively determined by something similar 
to a library version (the availability of the Perl Time::HiRes module) 
and it is expected to be important for debugging, which is the criteria 
stated for listing library versions.  Further, "should" does not express 
an absolute requirement and no rationale that would effectively make an 
absolute requirement (like a rule for automated parsing) is given here, 
unlike for the version in the first line.


-- Jacob