The main issue was use of s///r; the /r modifier was added in 5.14.
Since the baseline is now 5.10.0 instead of 5.6.0, a couple places
can be tidied up using slightly newer constructs.
* help-extract.pl: Use File::Spec::Functions instead of File::Spec
for reduced clunkiness.
(eval_qq_no_interpolation): Don’t use s///r. Do use \K and (?=...)
to match the empty string (but only in just the right locations),
so we don’t need to use $& in the replacement.
(main): Don’t use s///r.
The minimum Perl version was raised to 5.8.0 from 5.6.0 in commit
3a9802d601 (but not documented as
such until e8c2d79ec4, and not
actually *enforced* by our own configure script until, er, now)
in order to use Time::HiRes::stat.
Unfortunately, while the Time::HiRes *module* was added in 5.8.0, it
did not export a ‘stat’ function until 5.8.9. More precisely, this
feature was added to Time::HiRes in version 1.92 of that module; Perl
core 5.8.8 shipped Time::HiRes 1.86, 5.8.9 shipped 1.9715. The only
system I have convenient access to, that has older Perls installed,
offers me a choice of 5.8.8 or 5.10.1, so the new requirement means
I cannot test with 5.8.x anymore.
Per https://perldoc.perl.org/perlhist the release history of these
versions of Perl is, in chronological order,
5.8.0 2002-Jul-18
5.8.8 2006-Jan-31
5.10.0 2007-Dec-18
5.8.9 2008-Dec-14 <-- almost a year later than 5.10.0
5.10.1 2009-Aug-22
5.12.0 2010-Apr-12
Per https://perldoc.perl.org/perl5101delta the differences between
5.10.0 and 5.10.1 are small, and do not make me worry about
accidentally introducing code that works on my test boxes but not for
our users, unlike the gulf between 5.8.x and 5.10.x.
Requiring 5.10 will mean that we have access to Digest::SHA, the //
and //= operators, the regexp \K escape, and ‘state’ variables
(lexical scope, persistent value) all of which I can think
of uses for (but none of them are actually used in this patch).
Putting it all together, I think a requirement bump to version 5.10.0
is justified. We are already chopping off the trailing edge at 2006
due to the requirement for M4 1.4.8 (/de facto/ since 2.70) and late
2007 is still 15 years ago.
This patch also makes configure search $PATH for executables named
‘perl5*’ and ‘perl-5.*’ if bare ‘perl’ is too old. To do this, it
introduces a helper macro AClocal_PATH_PROG_GLOBS_FEATURE_CHECK, which
I would *like* to promote to a new Autoconf feature, but I got stuck
on quoting issues — see comments in m4/perl-time-hires.m4.
* NEWS: Document requirement for Perl 5.10.
* m4/perl-time-hires.m4: New file.
* configure.ac: Use AC_PATH_PERL_WITH_TIME_HIRES_STAT to probe for
perl.
* build-aux/fetch.pl (fetch): For .pm files fetched from Automake,
rewrite “use 5.006” to “use 5.010”.
* build-aux/help-extract.pl
* lib/Autom4te/C4che.pm
* lib/Autom4te/ChannelDefs.pm
* lib/Autom4te/Channels.pm
* lib/Autom4te/Config.pm
* lib/Autom4te/Configure_ac.pm
* lib/Autom4te/FileUtils.pm
* lib/Autom4te/General.pm
* lib/Autom4te/Getopt.pm
* lib/Autom4te/Request.pm
* lib/Autom4te/XFile.pm
* tests/mktests.pl: Change “use 5.006” to “use 5.010”.
Of all the installed programs (autoconf, autoheader, autom4te,
autoreconf, autoscan, autoupdate, ifnames) autoconf is the only one
that is a shell script instead of a Perl script. This means it has to
do a lot of fiddly quoting and requoting to assemble an autom4te
command line, it doesn’t get to use the shared option handling code in
Autom4te/{General,Getopt}.pm, and it has to duplicate usage text that
properly should only be in Autom4te/ChannelDefs.pm. It also means
there’s extra code in build-aux/help-extract.pl just for it, and a
special two-phase generation process in bin/local.mk.
This also paves the way for the bootstrap script mentioned in the
previous commit; it will only have to know how to deal with
substitution variables, not generation of m4sh scripts.
The new script winds up being slightly longer on disk but that’s
because our boilerplate for Perl scripts is quite long. The code is
visibly simpler.
* bin/autoconf.as: Rename to bin/autoconf.in and rewrite in Perl.
* bin/local.mk (EXTRA_DIST): Change autoconf.as to autoconf.in.
(MOSTLYCLEANFILES): Don’t delete autoconf.in.
(bin/autoconf.in): Delete rule.
(ETAGS_PERL): Add autoconf.in and sort list.
(ETAGS_SH): Delete, no longer needed.
* tests/tools.at: Syntax-check autoconf as a Perl script.
* build-aux/help-extract.pl: Remove all code for extracting usage text
from shell scripts.
* man/autoconf.w, man/local.mk: Refer to autoconf.in, not autoconf.as.
We generate manpages for autoconf’s installed programs (autoconf,
autoheader, etc.) using help2man, which runs each program in order to
learn its --help output. Each manpage therefore has a dependency on
the existence of the corresponding program, but this dependency is
intentionally left out of the Makefile so that one can build from a
tarball release (which will include prebuilt manpages) without having
help2man installed.
But when building from a git checkout with high levels of
parallelism (-j20 or so), the missing dependency can lead to build
failures, because help2man will try to run the program before it
exists. In an earlier patch I tried to work around this with a
recursive make invocation in the ‘.x.1’ rule, to ensure the existence
of the program. That only traded one concurrency bug for another, now
we could have two jobs trying to build the same program simultaneously
and they would clobber each other’s work and the build would still
fail.
Instead, this patch introduces a utility script ‘help-extract.pl’ that
reads --help and --version information directly from the source code
for each program. This utility, wrapped appropriately for each
program, is what help2man now runs. Usage is a little weird because
help2man doesn’t let you specify any arguments to the “executable”
that it runs, but it works, and lets us write all of the true
dependencies of each manpage into the Makefile without naming any file
that would be created during a build from a tarball. help-extract.pl
is a Perl script, so it introduces no new build-time requirements.
A downside is that we have to make sure each of the script sources in
bin/, and also part of lib/Autom4te/ChannelDefs.pm, are parseable by
help-extract. The most important constraints are that the text output
by --help must be defined in a global variable named ‘help’, and its
definition has to be formatted just the way these definitions are
currently formatted. Similarly for --version. Furthermore, only some
non-literal substitutions are possible in these texts; each has to be
explicitly supported in help-extract.pl. The current list of supported
substitutions is $0, @PACKAGE_NAME@, @VERSION@, @RELEASE_YEAR@, and
Autom4te::ChannelDefs::usage.
The generated manpages themselves are character-for-character
identical before and after this patch.
* build-aux/help-extract.pl: New build script that extracts --help
and --version output from manpages.
* man/autoconf.w, man/autoheader.w, man/autom4te.w, man/autoreconf.w
* man/autoscan.w, man/autoupdate.w, man/ifnames.w: New shell scripts
which wrap build-aux/help-extract.pl.
* man/local.mk: Generate each manpage by running help2man on the
corresponding .w script, not on the built utility itself.
Revise all dependencies to match.
* bin/autoconf.as: Rename ‘usage’ variable to ‘help’ and
‘help’ variable to ‘usage_err’.
* bin/autoheader.in: Call Autom4te::ChannelDefs::usage with no
function-call parentheses, matching all the other scripts.
* bin/autom4te.in: Initialize $version with a regular double-quoted
string, not a heredoc, matching all the other scripts.
* bin/autoscan.in: Remove global variable $configure_scan.
