A number of diff APIs and the `git_checkout_index` API take a
`git_repository` object an operate on the index. This updates
them to take a `git_index` pointer explicitly and only fall back
on the `git_repository` index if the index input is NULL. This
makes it easier to operate on a temporary index.
This fixes a number of warnings and problems with cross-platform
builds. Among other things, it's not safe to name a member of a
structure "strcmp" because that may be #defined.
This is a major reworking of checkout strategy options. The
checkout code is now sensitive to the contents of the HEAD tree
and the new options allow you to update the working tree so that
it will match the index content only when it previously matched
the contents of the HEAD. This allows you to, for example, to
distinguish between removing files that are in the HEAD but not
in the index, vs just removing all untracked files.
Because of various corner cases that arise, etc., this required
some additional capabilities in rmdir and other utility functions.
This includes the beginnings of an implementation of code to read
a partial tree into the index based on a pathspec, but that is
not enabled because of the possibility of creating conflicting
index entries.
This started as a complex new test for checkout going through the
"typechanges" test repository, but that revealed numerous issues
with checkout, including:
* complete failure with submodules
* failure to create blobs with exec bits
* problems when replacing a tree with a blob because the tree
"example/" sorts after the blob "example" so the delete was
being processed after the single file blob was created
This fixes most of those problems and includes a number of other
minor changes that made it easier to do that, including improving
the TYPECHANGE support in diff/status, etc.
Renamed git_checkout_index to what it really was,
and removed duplicate code from clone.c. Added
git_checkout_ref, which updates HEAD and hands off
to git_checkout_head.
Added tests for the options the caller can pass to
git_checkout_*.
