Prior to this patch "hg diff -U0", i.e., zero lines of context, would
output hunk headers with a start line one greater than what GNU patch
and git output. Guido van Rossum documents the unified diff format[1]
as having a start line value "one lower than one would expect" for
zero length hunks.
Comparing the behaviour of the three systems prior to this patch in
transforming
c1
c3
to
c1
c2
c3
- GNU "diff -U0" reports the hunk as "@@ -1,0 +2 @@"
- "git diff -U0" reports the hunk as "@@ -1,0 +2 @@"
- "hg diff -U0" reports the hunk as "@@ -2,0 +2,1 @@"
After this patch, "hg diff -U0" reports "@@ -1,0 +2,1 @@".
Since "hg export --config diff.unified=0" outputs zero-context unified
diffs, "hg import" has also been updated to account for start lines
one less than expected for zero length hunk ranges.
[1]: http://www.artima.com/weblogs/viewpost.jsp?thread=164293
splitblock() was added to handle blocks returned by bdiff.blocks() which differ
only by blank lines but are not made only of blank lines. I do not know exactly
how it could happen but mdiff.blocks() threshold behaviour makes me think it
can if those blocks are made of very popular lines mixed with popular blank
lines. If it is proven to be wrong, the function can be dropped.
The first implementation made annotate share diff configuration entries. But it
looks like users will user -w/b for annotate but not for diff, on both the
command line and hgweb. Since the latter cannot use command line entries, we
introduce a new [annotate] section duplicating the diff whitespace options.
The 'Bin' marker was added to every changed file for which we could not find
any diff changes. This included binary files but also copy/renames and mode
changes. Since Mercurial regular diff format emits a 'Binary file XXX has
changed' line when fed with binary files, we use that and the usual git marker
to tell them from other cases. In particular, new empty files are no longer
reported as binary.
Still, this fix is not complete since copy/renames/mode changes are now
reported as '0' lines changes, instead of 'Bin'.
The line content of continued Subject: lines was yet joined via
str.replace('\n\t', ' '), which does not handle continuation via
spaces. So expan the regular expression instead to
handle all allowed forms of mail header line continuation.
This feature is more a way to test patching without a working directory than
something people asked about. Adding a --rev option to specify the parent patch
revision would make it a little more useful.
What this change introduces is patch.repobackend class which let patches be
applied against repository revisions. The caller must supply a filestore object
to receive patched content, which can be turned into a memctx with
patch.makememctx() helper.
- Add patchmeta.copy() and emit copies from iterhunks. Modifying patchmeta
instances in applydiff() makes things simpler.
- Rename selectfile() into makepatchmeta(). It is responsible for creating
patchmeta for regular patches.
- Pass patchmeta objects to patchfile() directly
patchmeta instances were associated with git patches, for regular patches we
had to pass additional variables to tell the patch intent to patchfile().
Instead, we generate patchmeta for regular patches and pass them. This will
also help with patch filtering by matcher objects.
This information is more correctly returned by backends.
The extra updated file removed from test-mq-merge.t output came from changes
from git patches being counted before being really applied in some cases.
Synchronizing on bfile does not work on file removal where bfile is /dev/null.
We match items on afile or bfile instead. The incorrect code makes iterhunks()
to emit patchmeta and hunks separately in some cases. This is currently hidden
by applydiff() being too tolerant when processing patchmeta, and will be fixed
later.
git patches may require copies to be handled out-of-order. For instance, take
the following sequence:
* modify a
* copy a into b
Here, we have to generate b from a before its modification. To do so,
applydiff() was scanning for copy metadata and performing the copies before
processing the other changes in-order. While smart and efficient, this approach
complicates things by handling file copies and file creations at different
places and times. While a new file must not exist before being patched a copied
file already exists before applying the first hunk.
Instead of copying the files at their final destination before patching, we
store them in a temporary file location and retrieve them when patching. The
filestore always stores file content in real files but nothing prevents adding
a cache layer. The filestore class was kept separate from fsbackend for at
least two reasons:
- This class is likely to be reused as a temporary result store for a future
repository patching call (entries just have to be extended to contain copy
sources).
- Delegating this role to backends might be more efficient in a repository
backend case: the source files are already available in the repository itself
and do not need to be copied again. It also means that third-parties backend
would have to implement two other methods. If we ever decide to merge the
filestore feature into backend, a minimalistic approach would be to compose
with filestore directly. Keep in mind this copy overhead only applies for
copy/rename sources, and may even be reduced to copy sources which have to
handled ahead of time.
The patcher has to know if a file is being created or removed to check if the
target already exists, or to actually unlink the file when a hunk emptying it
is applied. This was done by embedding the creation/removal information in the
first (and only) hunk attached to the file.
There are two problems with this approach:
- creation/removal is really a property of the file being patched and not its
hunk.
- for regular patches, file creation cannot be deduced at parsing time: there
are case where the *stripped* file paths must be compared. Modifying hunks
after their creation is clumsy and prevent further refactorings related to
copies handling.
Instead, we delegate this job to selectfile() which has all the relevant
information, and remove the hunk createfile() and rmfile() methods.
Restore the previous diffstat behaviour of scaling by the maximum number of
changes to a single file. Changeset 7bb0e22a7988 modified the diffstat to be
scaled by the total number of changes. This seems to have been unintentional.
gitpatch objects emitted by iterhunks() were referencing file paths unmodified
from the input patch. _applydif() made them usable by modifying the gitpatch
objects in-place with specified path strip level. The same modified objects
were then reused by iterhunks() generator. _applydiff() now copies and update
the paths which completely decouples both routines.
As a side effect, the "git" event now receives only metadata about
copies/renames to perform the necessary copies ahead of time. Other actions are
handled in the "file" event.
Patch changes are emitted by iterhunks() in two separate events: 'file' when
hunks have to be applied and 'git' to describe other modifications like copies
or mode changes. Note that a file which mode is changed and which content is
modified by the same patch will be emitted in both events. It is more
convenient to handle all file modifications in a single event. This patch
"zips" git actions with regular changes so both kinds can be emitted at the
same place.
git afile/bfile are extracted twice, once when reading a 'diff --git', and
again when reading a unified hunk. The problem is not all git blocks have
unified hunks (renames just have metadata) and they were not extracted the same
way. This is what this patch unifies.
gitpatch objects emitted by iterhunks() are modified in place by applydiff().
Processing them earlier improves iterhunks() isolation. applydiff() modifying
them should still be fixed though.
_updatedir() is no longer used by internalpatch()
The change in test-mq-missingfiles.t comes from workingbackend not considering
the missing 'b' file as changed, thus not calling addremove() on it.
This introduces a performance regression for large files, as they will be
copied just to be clobbered afterwards since binary patching does not use
deltas. But it simplifies the code and the previous optimization will be
reintroduced later in a better way.
