Re: [PATCH/RFC] clone: report duplicate entries on case-insensitive filesystems

[Junio C Hamano <gitster@pobox.com>]

Elijah Newren <newren@gmail.com> writes:

> Is it worth attempting to also warn about paths that only differ in
> UTF-normalization on relevant MacOS systems?

I hate to bring up a totally different approach this late in the
party, but I wonder if it makes more sense to take advantage of
"clone" being a command that starts from an empty working tree.

builtin/clone.c::checkout() drives a single-tree unpack_trees(),
using oneway_merge() as its callback and at the end, eventually
unpack_trees.c:check_updates() will call into checkout_entry()
to perform the usual "unlink and then create" dance.

I wonder if it makes sense to introduce a new option to tell the
machinery to report when the final checkout_entry() notices that it
needed to remove the working tree file to make room (perhaps that
bit would go in "struct unpack_trees_options").  In the initial
checkout codepath for a freshly cloned repository, that would only
happen when your tree has two (or more) paths that gets smashed
by case insensitive or UTF-normalizing filesystem, and the code we
would maintain do not have to care how exactly the filesystem
collapses two (or more) paths if we go that way.  We only need to
report "we tried to check out X but it seems your filesystem equates
something else that is also in the project to X".