Function svn_path_remove_redundancies 

pub unsafe extern "C" fn svn_path_remove_redundancies(
    pcondensed_targets: *mut *mut apr_array_header_t,
    targets: *const apr_array_header_t,
    pool: *mut apr_pool_t,
) -> *mut svn_error_t

Copy a list of canonicalized @a targets, one at a time, into @a pcondensed_targets, omitting any targets that are found earlier in the list, or whose ancestor is found earlier in the list. Ordering of targets in the original list is preserved in the condensed list of targets. Use @a pool for any allocations.

How does this differ in functionality from svn_path_condense_targets()?

Here’s the short version:

1. Disclaimer: if you wish to debate the following, talk to Karl. :-) Order matters for updates because a multi-arg update is not atomic, and CVS users are used to, when doing ‘cvs up targetA targetB’ seeing targetA get updated, then targetB. I think the idea is that if you’re in a time-sensitive or flaky-network situation, a user can say, “I really need to update wc/A/D/G/tau, but I might as well update my whole working copy if I can.” So that user will do ‘svn up wc/A/D/G/tau wc’, and if something dies in the middles of the ‘wc’ update, at least the user has ‘tau’ up-to-date.

2. Also, we have this notion of an anchor and a target for updates (the anchor is where the update editor is rooted, the target is the actual thing we want to update). I needed a function that would NOT screw with my input paths so that I could tell the difference between someone being in A/D and saying ‘svn up G’ and being in A/D/G and saying ‘svn up .’ – believe it or not, these two things don’t mean the same thing. svn_path_condense_targets() plays with absolute paths (which is fine, so does svn_path_remove_redundancies()), but the difference is that it actually tweaks those targets to be relative to the “grandfather path” common to all the targets. Updates don’t require a “grandfather path” at all, and even if it did, the whole conversion to an absolute path drops the crucial difference between saying “i’m in foo, update bar” and “i’m in foo/bar, update ‘.’”