Re: icase pathspec magic support in ls-tree

> Hi folks,
>
> I just found out today both that icase magic exists (awesome!), and
> that it isn't supported in ls-tree (boo).
>
> As far as I can tell, getting it supported would be the only way to
> *efficiently* prevent caseless-duplicate files from being created in a
> repo, in an "update" hook: I'd want to call ls-tree on the new head
> commit for the branch, passing in an icase pathspec for all the files
> being added since the previous state - and then sort and uniq.
>
> Of course, for entirely new branches I'd have to do a full check of
> the tree, and for very large changes that might be the fastest/best
> thing to do anyway, rather than creating a silly-sized pathspec - but
> checking the full tree costs me about 1 second, a price that I'm loath
> to pay for everyday commit verifications of a handful of files, vs a
> 200,000-file full tree.
>
> I tried changing ls-tree "naively" to just permit the icase magic,
> without any logic changes, and found at least one case where it
> doesn't work: when combining wildcards with case-insensitivity, like
> an icased "T/*" patchspec in the git repo; ls-files finds all the
> tests, and a naively updated ls-tree does not.
>
> I think I see the last person to update this was Nguyễn Thái Ngọc Duy
> in 2013, giving a hint as to what would need to be done to make this
> be supported; is this an area anyone else might be looking at at the
> moment?