Take a look at config/initializers/inflections.rb and add to the block:
inflect.irregular 'slice', 'slices'

I think this issue can be closed ?

I can do that, however it still seems like a bug since the model layer was generated correctly using Slice, and the controller should really be doing Slice.all, not Slices (or Slouse) .all

Feel free to close the issue if you disagree.

I tried this on rails HEAD and it is still broken. It appears the ActiveSupport::Inflector doesn't anchor the regex that looks for (m|l)ice$ to the start of the string. So any word that ends in (m|l)ice will match as a plural and AS will incorrectly turn it into ...ouse for the model name.

Here is a list of words from /usr/share/dict that end in (m|l)ice:

accomplice
Alice
allice
amice
chalice
cilice
complice
Ellice
enchalice
fortalice
malice
mice
police
prepolice
pumice
pummice
resplice
slice
splice
supplice
surplice
Triplice
undersplice
unsurplice

As you can see, many of them are not plurals of a word that ends in ...ouse.

Fix forthcoming.

This pull request fixes the problem: #5177

A placemarker for follow-up (@jeremyf)

Pull request was merged, closing here, thanks!