Forbids rename detection logic from matching two empty files as renames
during merge-recursive to prevent mismerges.
By Jeff King
* jk/diff-no-rename-empty:
merge-recursive: don't detect renames of empty files
teach diffcore-rename to optionally ignore empty content
make is_empty_blob_sha1 available everywhere
drop casts from users EMPTY_TREE_SHA1_BIN
Resurrects the preparatory clean-up patches from another topic that was
discarded, as this would give a saner foundation to build on diff.algo
configuration option series.
* jc/diff-algo-cleanup:
xdiff: PATIENCE/HISTOGRAM are not independent option bits
xdiff: remove XDL_PATCH_* macros
Merge-recursive detects renames so that if one side modifies
"foo" and the other side moves it to "bar", the modification
is applied to "bar". However, our rename detection is based
on content analysis, it can be wrong (i.e., two files were
not intended as a rename, but just happen to have the same
or similar content).
This is quite rare if the files actually contain content,
since two unrelated files are unlikely to have exactly the
same content. However, empty files present a problem, in
that there is nothing to analyze. An uninteresting
placeholder file with zero bytes may or may not be related
to a placeholder file with another name.
The result is that adding content to an empty file may cause
confusion if the other side of a merge removed it; your
content may end up in another random placeholder file that
was added.
Let's err on the side of caution and not consider empty
files as renames. This will cause a modify/delete conflict
on the merge, which will let the user sort it out
themselves.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This macro already evaluates to the correct type, as it
casts the string literal to "unsigned char *" itself
(and callers who want the literal can use the _LITERAL
form).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Because the default Myers, patience and histogram algorithms cannot be in
effect at the same time, XDL_PATIENCE_DIFF and XDL_HISTOGRAM_DIFF are not
independent bits. Instead of wasting one bit per algorithm, define a few
macros to access the few bits they occupy and update the code that access
them.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* tr/cache-tree:
reset: update cache-tree data when appropriate
commit: write cache-tree data when writing index anyway
Refactor cache_tree_update idiom from commit
Test the current state of the cache-tree optimization
Add test-scrap-cache-tree
We'll need to safely create or update the cache-tree data of the_index
from other places. While at it, give it an argument that lets us
silence the messages produced by unmerged entries (which prevent it
from working).
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The merge-recursive code uses the commit->util field directly to annotate
the commit objects given from the command line, i.e. the remote heads to
be merged, with a single string to be used to describe it in its trace
messages and conflict markers.
Correct this short-signtedness by redefining the field to be a pointer to
a structure "struct merge_remote_desc" that later enhancements can add
more information. Store the original objects we were told to merge in a
field "obj" in this struct, so that we can recover the tag we were told to
merge.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The submodule merge search is not useful during virtual merges because
the results cannot be used automatically. Furthermore any suggestions
made by the search may apply to commits different than HEAD:sub and
MERGE_HEAD:sub, thus confusing the user. Skip searching for submodule
merges during a virtual merge such as that between B and C while merging
the heads of:
B---BC
/ \ /
A X
\ / \
C---CB
Run the search only when the recursion level is zero (!o->call_depth).
This fixes known breakage tested in t7405-submodule-merge.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix another instance of a recursive merge incorrectly paying attention to
the working tree file during a virtual ancestor merge, that resulted in
spurious and useless "addinfo_cache failed" error message.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The git term is 'working tree', so replace the most public references
to 'working copy'.
Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* en/merge-recursive-2: (57 commits)
merge-recursive: Don't re-sort a list whose order we depend upon
merge-recursive: Fix virtual merge base for rename/rename(1to2)/add-dest
t6036: criss-cross + rename/rename(1to2)/add-dest + simple modify
merge-recursive: Avoid unnecessary file rewrites
t6022: Additional tests checking for unnecessary updates of files
merge-recursive: Fix spurious 'refusing to lose untracked file...' messages
t6022: Add testcase for spurious "refusing to lose untracked" messages
t3030: fix accidental success in symlink rename
merge-recursive: Fix working copy handling for rename/rename/add/add
merge-recursive: add handling for rename/rename/add-dest/add-dest
merge-recursive: Have conflict_rename_delete reuse modify/delete code
merge-recursive: Make modify/delete handling code reusable
merge-recursive: Consider modifications in rename/rename(2to1) conflicts
merge-recursive: Create function for merging with branchname:file markers
merge-recursive: Record more data needed for merging with dual renames
merge-recursive: Defer rename/rename(2to1) handling until process_entry
merge-recursive: Small cleanups for conflict_rename_rename_1to2
merge-recursive: Fix rename/rename(1to2) resolution for virtual merge base
merge-recursive: Introduce a merge_file convenience function
merge-recursive: Fix modify/delete resolution in the recursive case
...
When this code was first written (v1.4.3-rc1~174^2~4, merge-recur: if
there is no common ancestor, fake empty one, 2006-08-09), everyone
needing a fake empty tree had to make her own, but ever since
v1.5.5-rc0~180^2~1 (2008-02-13), the object lookup machinery provides
a ready-made one. Use it.
This is just a simplification, though it also fixes a small leak
(since the tree in the virtual common ancestor commit is never freed).
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In record_df_conflict_files() we would resort the entries list using
df_name_compare to get a convenient ordering. Unfortunately, this broke
assumptions of the get_renames() code (via string_list_lookup() calls)
which needed the list to be in the standard ordering. When those lookups
would fail, duplicate stage_data entries could be inserted, causing the
process_renames and process_entry code to fail (in particular, a path that
that process_renames had marked as processed would still be processed
anyway in process_entry due to the duplicate entry).
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Earlier in this series, the patch "merge-recursive: add handling for
rename/rename/add-dest/add-dest" added code to handle the rename on each
side of history also being involved in a rename/add conflict, but only
did so in the non-recursive case. Add code for the recursive case,
ensuring that the "added" files are not simply deleted.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Often times, a potential conflict at a path is resolved by merge-recursive
by using the content that was already present at that location. In such
cases, we do not want to overwrite the content that is already present, as
that could trigger unnecessary recompilations. One of the patches earlier
in this series ("merge-recursive: When we detect we can skip an update,
actually skip it") fixed the cases that involved content merges, but there
were a few other cases as well.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Calling update_stages() before update_file() can sometimes result in git
thinking the file being updated is untracked (whenever update_stages
moves it to stage 3). Reverse the call order, and add a big comment to
update_stages to hopefully prevent others from making the same mistake.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If either side of a rename/rename(1to2) conflict is itself also involved
in a rename/add-dest conflict, then we need to make sure both the rename
and the added file appear in the working copy.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Each side of the rename in rename/rename(1to2) could potentially also be
involved in a rename/add conflict. Ensure stages for such conflicts are
also recorded.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
modify/delete and rename/delete share a lot of similarities; we'd like all
the criss-cross and D/F conflict handling specializations to be shared
between the two.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our previous conflict resolution for renaming two different files to the
same name ignored the fact that each of those files may have modifications
from both sides of history to consider. We need to do a three-way merge
for each of those files, and then handle the conflict of both sets of
merged contents trying to be recorded with the same name.
It is important to note that this changes our strategy in the recursive
case. After doing a three-way content merge of each of the files
involved, we still are faced with the fact that we are trying to put both
of the results (including conflict markers) into the same path. We could
do another two-way merge, but I think that becomes confusing. Also,
taking a hint from the modify/delete and rename/delete cases we handled
earlier, a more useful "common ground" would be to keep the three-way
content merge but record it with the original filename. The renames can
still be detected, we just allow it to be done in the o->call_depth=0
case. This seems to result in simpler & easier to understand merge
conflicts as well, as evidenced by some of the changes needed in our
testsuite in t6036. (However, it should be noted that this change will
cause problems those renames also occur along with a file being added
whose name matches the source of the rename. Since git currently cannot
detect rename/add-source situations, though, this codepath is not
currently used for those cases anyway.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We want to be able to reuse the code to do a three-way file content merge
and have the conflict markers use both branchname and filename. Split it
out into a separate function.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When two different files are renamed to one, we need to be able to do
three-way merges for both of those files. To do that, we need to record
the sha1sum of the (possibly modified) file on the unrenamed side. Modify
setup_rename_conflict_info() to take this extra information and record it
when the rename_type is RENAME_TWO_FILES_TO_ONE.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This puts the code for the different types of double rename conflicts
closer together (fewer lines of other code separating the two paths) and
increases similarity between how they are handled.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When renaming one file to two files, we really should be doing a content
merge. Also, in the recursive case, undoing the renames and recording the
merged file in the index with the source of the rename (while deleting
both destinations) allows the renames to be re-detected in the
non-recursive merge and will result in fewer spurious conflicts.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge_file previously required diff_filespec arguments, but all callers
only had sha1s and modes. Rename merge_file to merge_file_1 and introduce
a new merge_file convenience function which takes the sha1s and modes and
creates the temporary diff_filespec variables needed to call merge_file_1.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When o->call_depth>0 and we have conflicts, we try to find "middle ground"
when creating the virtual merge base. In the case of content conflicts,
this can be done by doing a three-way content merge and using the result.
In all parts where the three-way content merge is clean, it is the correct
middle ground, and in parts where it conflicts there is no middle ground
but the conflict markers provide a good compromise since they are unlikely
to accidentally match any further changes.
In the case of a modify/delete conflict, we cannot do the same thing.
Accepting either endpoint as the resolution for the virtual merge base
runs the risk that when handling the non-recursive case we will silently
accept one person's resolution over another without flagging a conflict.
In this case, the closest "middle ground" we have is actually the merge
base of the candidate merge bases. (We could alternatively attempt a
three way content merge using an empty file in place of the deleted file,
but that seems to be more work than necessary.)
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 882fd11 (merge-recursive: Delay content merging for renames 2010-09-20),
there was code that checked for whether we could skip updating a file in
the working directory, based on whether the merged version matched the
current working copy. Due to the desire to handle directory/file conflicts
that were resolvable, that commit deferred content merging by first
updating the index with the unmerged entries and then moving the actual
merging (along with the skip-the-content-update check) to another function
that ran later in the merge process. As part moving the content merging
code, a bug was introduced such that although the message about skipping
the update would be printed (whenever GIT_MERGE_VERBOSITY was sufficiently
high), the file would be unconditionally updated in the working copy
anyway.
When we detect that the file does not need to be updated in the working
copy, update the index appropriately and then return early before updating
the working copy.
Note that there was a similar change in b2c8c0a (merge-recursive: When we
detect we can skip an update, actually skip it 2011-02-28), but it was
reverted by 6db4105 (Revert "Merge branch 'en/merge-recursive'"
2011-05-19) since it did not fix both of the relevant types of unnecessary
update breakages and, worse, it made use of some band-aids that caused
other problems. The reason this change works is due to the changes earlier
in this series to (a) record_df_conflict_files instead of just unlinking
them early, (b) allowing make_room_for_path() to remove D/F entries,
(c) the splitting of update_stages_and_entry() to have its functionality
called at different points, and (d) making the pathnames of the files
involved in the merge available to merge_content().
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Whenever there are merge conflicts in file contents, we would mark the
different sides of the conflict with the two branches being merged.
However, when there is a rename involved as well, the branchname is not
sufficient to specify where the conflicting content came from. In such
cases, mark the two sides of the conflict with branchname:filename rather
than just branchname.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The consolidation of process_entry() and process_df_entry() allows us to
consolidate more code paths concerning rename conflicts, and to do
a few additional related cleanups. It also means we are using
rename_df_conflict_info in some cases where there is no D/F conflict;
rename it to rename_conflict_info.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The whole point of adding process_df_entry() was to ensure that files of
D/F conflicts were processed after paths under the corresponding
directory. However, given that the entries are in sorted order, all we
need to do is iterate through them in reverse order to achieve the same
effect. That lets us remove some duplicated code, and lets us keep
track of one less thing as we read the code ("do we need to make sure
this is processed before process_df_entry() or do we need to defer it
until then?").
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When dealing with file merging and renames and D/F conflicts and possible
criss-cross merges (how's that for a corner case?), we did not do a
thorough job ensuring the index and working directory had the correct
contents. Fix the logic in merge_content() to handle this. Also,
correct some erroneous tests in t6022 that were expecting the wrong number
of unmerged index entries. These changes fix one of the tests in t6042
(and almost fix another one from t6042 as well).
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are a couple of places where changes are needed to for situations
involving rename/add-source issues. Add comments about the needed changes
(and existing bugs) until git has been enabled to detect such cases.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code for rename_rename_2to1 conflicts (two files both being renamed to
the same filename) was dead since the rename/add path was always being
independently triggered for each of the renames instead. Further,
reviving the dead code showed that it was inherently buggy and would
always segfault -- among a few other bugs.
Move the else-if branch for the rename/rename block before the rename/add
block to make sure it is checked first, and fix up the rename/rename(2to1)
code segments to make it handle most cases. Work is still needed to
handle higher dimensional corner cases such as rename/rename/modify/modify
issues.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the recursive case (o->call_depth > 0), we do not modify the working
directory. However, when o->call_depth==0, file renames can mean we need
to delete the old filename from the working copy. Since there have been
lots of changes and mistakes here, let's go through the details. Let's
start with a simple explanation of what we are trying to achieve:
Original goal: If a file is renamed on the side of history being merged
into head, the filename serving as the source of that rename needs to be
removed from the working directory.
The path to getting the above statement implemented in merge-recursive took
several steps. The relevant bits of code may be instructive to keep in
mind for the explanation, especially since an English-only description
involves double negatives that are hard to follow. These bits of code are:
int remove_file(..., const char *path, int no_wd)
{
...
int update_working_directory = !o->call_depth && !no_wd;
and
remove_file(o, 1, ren1_src, <expression>);
Where the choice for <expression> has morphed over time:
65ac6e9 (merge-recursive: adjust to loosened "working file clobbered"
check 2006-10-27), introduced the "no_wd" parameter to remove_file() and
used "1" for <expression>. This meant ren1_src was never deleted, leaving
it around in the working copy.
In 8371234 (Remove uncontested renamed files during merge. 2006-12-13),
<expression> was changed to "index_only" (where index_only ==
!!o->call_depth; see b7fa51da). This was equivalent to using "0" for
<expression> (due to the early logic in remove_file), and is orthogonal to
the condition we actually want to check at this point; it resulted in the
source file being removed except when index_only was false. This was
problematic because the file could have been renamed on the side of history
including head, in which case ren1_src could correspond to an untracked
file that should not be deleted.
In 183d797 (Keep untracked files not involved in a merge. 2007-02-04),
<expression> was changed to "index_only || stage == 3". While this gives
correct behavior, the "index_only ||" portion of <expression> is
unnecessary and makes the code slightly harder to follow.
There were also two further changes to this expression, though without
any change in behavior. First in b7fa51d (merge-recursive: get rid of the
index_only global variable 2008-09-02), it was changed to "o->call_depth
|| stage == 3". (index_only == !!o->call_depth). Later, in 41d70bd6
(merge-recursive: Small code clarification -- variable name and comments),
this was changed to "o->call_depth || renamed_stage == 2" (where stage was
renamed to other_stage and renamed_stage == other_stage ^ 1).
So we ended with <expression> being "o->call_depth || renamed_stage == 2".
But the "o->call_depth ||" piece was unnecessary. We can remove it,
leaving us with <expression> being "renamed_stage == 2". This doesn't
change behavior at all, but it makes the code clearer. Which is good,
because it's about to get uglier.
Corrected goal: If a file is renamed on the side of history being merged
into head, the filename serving as the source of that rename needs to be
removed from the working directory *IF* that file is tracked in head AND
the file tracked in head is related to the original file.
Note that the only difference between the original goal and the corrected
goal is the two extra conditions added at the end. The first condition is
relevant in a rename/delete conflict. If the file was deleted on the
HEAD side of the merge and an untracked file of the same name was added to
the working copy, then without that extra condition the untracked file
will be erroneously deleted. This changes <expression> to "renamed_stage
== 2 || !was_tracked(ren1_src)".
The second additional condition is relevant in two cases.
The first case the second condition can occur is when a file is deleted
and a completely different file is added with the same name. To my
knowledge, merge-recursive has no mechanism for detecting deleted-and-
replaced-by-different-file cases, so I am simply punting on this
possibility.
The second case for the second condition to occur is when there is a
rename/rename/add-source conflict. That is, when the original file was
renamed on both sides of history AND the original filename is being
re-used by some unrelated (but tracked) content. This case also presents
some additional difficulties for us since we cannot currently detect these
rename/rename/add-source conflicts; as long as the rename detection logic
"optimizes" by ignoring filenames that are present at both ends of the
diff, these conflicts will go unnoticed. However, rename/rename conflicts
are handled by an entirely separate codepath not being discussed here, so
this case is not relevant for the line of code under consideration.
In summary:
Change <expression> from "o->call_depth || renamed_stage == 2" to
"renamed_stage == 2 || !was_tracked(ren1_src)", in order to remove
unnecessary code and avoid deleting untracked files.
96 lines of explanation in the changelog to describe a one-line fix...
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of having the process_renames logic update the stages in the index
for the rename destination, have the index updated after process_entry or
process_df_entry. This will also allow us to have process_entry determine
whether a file was tracked and existed in the working copy before the
merge started.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If there were several files conflicting below a directory corresponding
to a D/F conflict, and the file of that D/F conflict is in the way, we
want it to be removed. Since files of D/F conflicts are handled last,
they can be reinstated later and possibly with a new unique name.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Checking whether a filename was part of stage 0 or stage 2 is code that we
would like to be able to call from a few other places without also
lstat()-ing the file to see if it exists in the working copy.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Rename make_room_for_directories_of_df_conflicts() to
record_df_conflict_files() to reflect the change in functionality.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previously, we were using lstat() to determine if a directory was still
present after a merge (and thus in the way of adding a file). We should
have been using lstat() only to determine if untracked directories were in
the way (and then only when necessary to check for untracked directories);
we should instead using the index to determine if there is a tracked
directory in the way. Create a new function to do this and use it to
replace the existing checks for directories being in the way.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We cannot assume that directory/file conflicts will appear in sorted
order; for example, 'letters.txt' comes between 'letters' and
'letters/file'.
Thanks to Johannes for a pointer about qsort stability issues with
Windows and suggested code change.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a D/F conflict is introduced via an add/add conflict, when
o->call_depth > 0 we need to ensure that the higher stage entry from the
base stage is removed.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
make_room_for_directories_of_df_conflicts() is about making sure necessary
working directory changes can succeed. When o->call_depth > 0 (i.e. the
recursive case), we do not want to make any working directory changes so
this function should be skipped.
Note that make_room_for_directories_of_df_conflicts() is broken as has
been pointed out by Junio; it should NOT be unlinking files. What it
should do is keep track of files that could be unlinked if a directory
later needs to be written in their place. However, that work also is only
relevant in the non-recursive case, so this change is helpful either way.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We are only calling update_stages_options() one way really, so we can
consolidate the slightly different variants into one and remove some
parameters whose values are always the same.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
