$ cpanm WWW::Mechanize::Firefox
--> Working on WWW::Mechanize::Firefox
...

after installing many many packages, we finally see

Building and testing HTML-Selector-XPath-0.15 ... OK
Successfully installed HTML-Selector-XPath-0.15
! Bailing out the installation for WWW-Mechanize-Firefox-0.68. Retry with --prompt or --force.
23 distributions installed
$ pm-uninstall WWW::Mechanize::Firefox
--> Working on WWW::Mechanize::Firefox
! WWW::Mechanize::Firefox not found.
$ pm-uninstall -v WWW::Mechanize::Firefox
--> Working on WWW::Mechanize::Firefox
Finding WWW::Mechanize::Firefox in your @INC
Looking up WWW::Mechanize::Firefox on cpanmetadb
-> Fetching from http://cpanmetadb.plackperl.org/v1.0/package/WWW::Mechanize::Firefox
! WWW::Mechanize::Firefox not found.


1. it doesn't look at my filesystem, but instead somewhere other than
cpanm did.

2. my system is left with ever increasing amounts of cruft.

I'm not sure if I understand this. You are trying to remove a distribution
(WWW::Mechanize::Firefox) which isn't installed, since its installation failed.

pm-uninstall *is* looking at your filesystem, but it doesn't find the files it
should remove since they were not installed in the first place.

Do you mean that pm-uninstall should remove the dependencies of
WWW::Mexhanize::Firefox?

Cheers

AG> Do you mean that pm-uninstall should remove the dependencies of
AG> WWW::Mexhanize::Firefox?

Yes! Else there is no way the user can back out of any of this, failed
or not, and get his filesystem back to the state where it was.

At least the dependencies that were find -mmin -15 ago installed...

As we see unless a full apt like system is created... there will be complications...

forwarded 693860 https://rt.cpan.org/Ticket/Display.html?id=81412
kthxbye

Right. pm-uninstall has some sort of support for dependencies, but it is only
used when uninstalling a module to check that no other module depends on it, so
I opened a new ticket upstream.

Cheers

Thanks!