Doing diffs for merges are special; they should typically avoid history
simplification. For example, with
git log --diff-merges=first-parent -- path
the default history simplification would remove merge commits from
consideration if the file "path" matched the second parent. That is
counter to what the user wants when looking for first-parent diffs.
Similar comments can be made for --diff-merges=separate (which diffs
against both parents) and --diff-merges=remerge (which diffs against a
remerge of the merge commit).
However, history simplification still makes sense if not doing diffing
merges, and it also makes sense for the combined and dense-combined
forms of diffing merges (because both of those are defined to only show
a diff when the merge result at the relevant paths differs from *both*
parents).
So, for separate, first-parent, and remerge styles of diff-merges, turn
off history simplification.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Conflicts such as modify/delete, rename/rename, or file/directory are
not representable via content conflict markers, and the normal output
messages notifying users about these were dropped with --remerge-diff.
While we don't want these messages randomly shown before the commit
and diff headers, we do want them to still be shown; include them as
part of the diff headers instead.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When this option is specified, we remerge all (two parent) merge commits
and diff the actual merge commit to the automatically created version,
in order to show how users removed conflict markers, resolved the
different conflict versions, and potentially added new changes outside
of conflict regions in order to resolve semantic merge problems (or,
possibly, just to hide other random changes).
This capability works by creating a temporary object directory and
marking it as the primary object store. This makes it so that any blobs
or trees created during the automatic merge are easily removable
afterwards by just deleting all objects from the temporary object
directory.
There are a few ways that this implementation is suboptimal:
* `log --remerge-diff` becomes slow, because the temporary object
directory can fill with many loose objects while running
* the log output can be muddied with misplaced "warning: cannot merge
binary files" messages, since ll-merge.c unconditionally writes those
messages to stderr while running instead of allowing callers to
manage them.
* important conflict and warning messages are simply dropped; thus for
conflicts like modify/delete or rename/rename or file/directory which
are not representable with content conflict markers, there may be no
way for a user of --remerge-diff to know that there had been a
conflict which was resolved (and which possibly motivated other
changes in the merge commit).
* when fixing the previous issue, note that some unimportant conflict
and warning messages might start being included. We should instead
make sure these remain dropped.
Subsequent commits will address these issues.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
