Regarding the "experiment" I mentioned above, here is a similar idea from the discussion at p5p cited by syphilis, posted afterwards: https://www.nntp.perl.org/group/perl.perl5.porters/2020/06/msg257591.html (comment by Karen Etheridge on June 26, 2020 18:04 - minor 1' edit tos supplement this info):

One thing that could help (and I have asked for this in the past;
unfortunately I have lacked the tuits to do it myself) is to compile
variants of perl with these pragmas forcibly turned on, and smoke all of
cpan with it to see the outcome.  As a cpan author and janitor, I would
certainly appreciate being able to see which distributions within my
control are affected by certain pragma or feature options, so that I can
proactively move to make appropriate fixes.  There may also be some
surprising findings from this exercise that would help inform us which
pragmas and features should be enabled or not enabled.  Core and dual-life
modules would also no doubt be affected, and they MUST all be fixed for
whatever default feature set is decided upon.

I think this is important. The logical next step, as I proposed, should be "measuring" the difficulty of the fixes by randomly selecting and fixing some modules and then extrapolating that figure for all Perl code "out there" using some rules of thumb not least of which: how exposed is the code to peer reviews (e.g. public CPAN module vs private/corporate) - but how to do this is a minor detail. Saying "X% of randomly selected modules were fixed 'easily' and Y% harder" is the important bit (so please no nit-picking).

bw, bliako