Re: [PATCH 01/18] t: add skeleton chainlint.pl

[Eric Sunshine <sunshine@sunshineco.com>]

On Thu, Sep 1, 2022 at 8:32 AM Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
> On Thu, Sep 01 2022, Eric Sunshine via GitGitGadget wrote:
> > From: Eric Sunshine <sunshine@sunshineco.com>
> > [...]
> > diff --git a/t/chainlint.pl b/t/chainlint.pl
>
> I really like this overall direction...

Thanks for running an eye over the patches.

> > +use warnings;
> > +use strict;
>
> I think that in general we're way overdue for at least a :
>
>         use v5.10.1;
>
> Or even something more aggresive, I think we can definitely depend on a
> newer version for this bit of dev tooling.

Being stuck with an 11+ year-old primary development machine which
can't be upgraded to a newer OS due to vendor end-of-life declaration,
and with old tools installed, I have little or no interest in bumping
the minimum version, especially since older Perl versions are
perfectly adequate for this task. Undertaking such a version bump
would also be outside the scope of this patch series (and I simply
don't have the free time or desire to pursue it).

> That makes a lot of things in this series more pleasing to look
> at. E.g. you could use named $+{} variables for regexes.

Perhaps, but (1) that would not be very relevant for this script which
typically only extracts "$1", and (2) I've rarely found cases when
named variables help significantly with clarity, but then most of my
real-life regexes generally only extract one or two bits of
information, periodically three, and those bits ("$1", "$2", etc.) are
immediately assigned to variables with meaningful names.

> > +package ScriptParser;
>
> I really wish this could be changed to just put this in
> t/chainlint/ScriptParser.pm early on, we could set @INC appropriately
> and "use" these, which...

I intentionally avoided splitting this into multiple modules because I
wanted it to be easy drop into or adapt to other projects (i.e.
sharness[1]). Of course, it is effectively a shell parser written in
Perl, and it's conceivable that the parser part of it could have uses
outside of Git, so modularizing it might be a good idea, but that's a
task for some future date if such a need arises.

[1]: https://github.com/chriscool/sharness

> > +my $getnow = sub { return time(); };
> > +my $interval = sub { return time() - shift; };
>
> Would eliminate any scoping concerns about this sort of thing.

As above, this is easily addressed if/when someone ever wants to reuse
the code outside of Git for some other purpose. I doubt it's worth
worrying about now.

> > +if (eval {require Time::HiRes; Time::HiRes->import(); 1;}) {
> > +     $getnow = sub { return [Time::HiRes::gettimeofday()]; };
> > +     $interval = sub { return Time::HiRes::tv_interval(shift); };
> > +}
>
> Is this "require" even needed, Time::HiRes is there since 5.7.* says
> "corelist -l Time::HIRes".

Unfortunately, this is needed. The Windows CI instances the Git
project uses don't have Time::HiRes installed (and it's outside the
scope of this series to address shortcomings in the CI
infrastructure).

> > +sub check_script {
> > +     my ($id, $next_script, $emit) = @_;
> > +     my ($nscripts, $ntests, $nerrs) = (0, 0, 0);
> > +     while (my $path = $next_script->()) {
> > +             $nscripts++;
> > +             my $fh;
> > +             unless (open($fh, "<", $path)) {
> > +                     $emit->("?!ERR?! $path: $!\n");
>
> If we can depend on v5.10.1 this can surely become:
>
>         use autodie qw(open close);
>
> No?

No. It's clipped in your response, but the full snippet looks like this:

    unless (open($fh, "<", $path)) {
        $emit->("?!ERR?! $path: $!\n");
        next;
    }

The important point is that I _don't_ want the program to "die" if it
can't open an input file; instead, it should continue processing all
the other input files, and the open-failure should be reported as just
another error/problem it encountered along the way.