Optionally Suppress Version Number Comments (Allow Deterministic Builds)

[chromatic]

I'm working on a system attempting to produce reproducible builds. When a Perl module uses a stack which includes Pod::Simple in the build process (such as using Pod::Man to generate man pages), the resulting output includes the version numbers of Pod::Simple.

For example, when building Mojolicious, the generated output for binaries such as morbo includes:

.\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.42)
.\"
.\" Standard preamble:
.\" ========================================================================

I'd like to be able to consolidate built modules when the output is bit-for-bit identical.

It's okay if Pod::Simple generates different output when the behavior of the module changes. However, if I had a way to suppress version number output in certain circumstances, I could re-use more built modules because there'd be fewer differences between them.

Ideally I could set an environment variable in my build system that would cover all of the cases where Pod::Simple may be invoked during a build process.

I'm happy to explain further or elaborate if my use case is still fuzzy.

[haarg]

This is done by Pod::Man, which is part of the podlators distribution, not Pod-Simple.

[haarg]

https://github.com/rra/podlators/blob/main/lib/Pod/Man.pm#L1117

[chromatic]

I was thinking of a way to suppress or simplify the output of the version_report method in Pod::Simple. If you think suppressing the output altogether in podlators is preferable, I'm happy to migrate this issue to that distribution.

[haarg]

It doesn't make much sense to me that a method named version_report would produce anything other than a version report.

None of the modules in this dist include the output from version_report. And even in podlators, it appears that only Pod::Man does. It may be reasonable to just remove it from there without an option.

[chromatic]

Thanks for the recommendation. I'll close this in favor of a similar query with podlators.

[rra]

For the record, the reason why Pod::Man does this is due to this statement in perlpodspec:

• When rendering Pod to a format that allows comments (i.e., to nearly any format other than plaintext), a Pod formatter must insert comment text identifying its name and version number, and the name and version numbers of any modules it might be using to process the Pod.

I'm therefore hesitant to change Pod::Man to stop doing this unless perlpodspec is changed. (The other modules in the podlators distribution fall under the "do not allow comments" exception.)

[haarg]

That seems like a pretty strange thing to have in the spec, and I would support removing it. Most other formatters don't follow that rule, including many that allow comments.

[rra]

Who owns perlpodspec these days? Is it maintained directly in the main Perl 5 repository? I can submit a PR.

[haarg]

Yes, perlpodspec is maintained in core.