dh-perl6 vs. dh-raku: reproducibility issues with vendor/precompiled

[Vagrant Cascadian]

Hi folks!

I just noticed a reproducibility issue in a package that transitioned
from dh-perl6 to dh-raku, and it introduced some reproducibility issues
in the raku-tap-harness in precomp files, e.g.:

  /usr/lib/perl6/vendor/precomp/69C6BF38EFE2DAC4C04DDF24DDCABC2CDF55A623/19/19DE6D93D4B9F2400823F8E9A00C571E42ADF6C3

Before switching from dh-perl6 to dh-raku, raku-tap-harness seemed to
consistently build reproducibly, and when I reverted back to using
dh-perl6 ant tested locally, it built reproducibly.


We're tracking this issue in reproducible builds as:

  https://tests.reproducible-builds.org/debian/issues/unstable/randomness_in_perl6_precompiled_libraries_issue.html

But there aren't many packages there (yay?), and the description is a
bit terse suggesting that these files should not be shipped at all...


Not knowing much about perl6 ... are the precompiled files needed in
installed packages?  Could they be generated at package install time
rather than package build time (like .pyc files for python in Debian)?
They appear to be hashed filenames, what goes into the hash that
produces them (file path? timestamp? etc.), and could that be made
reproducible?


There were also some embedded build paths in this build done recently:

  https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/diffoscope-results/raku-tap-harness.html
  
                 vs.
ntArrayB.../buil    ntArrayF.../buil
d/1st/raku-tap-h    d/2/raku-tap-har
arness-0.2.1....    ness-0.2.1/2nd..

Though I was unable to reproduce this locally...


Thanks!


live well,
  vagrant
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