ae3f36dea1
Commits that make formatting changes or function renames are often not interesting when blaming a file. A user may deem such a commit as 'not interesting' and want to ignore and its changes it when assigning blame. For example, say a file has the following git history / rev-list: ---O---A---X---B---C---D---Y---E---F Commits X and Y both touch a particular line, and the other commits do not: X: "Take a third parameter" -MyFunc(1, 2); +MyFunc(1, 2, 3); Y: "Remove camelcase" -MyFunc(1, 2, 3); +my_func(1, 2, 3); git-blame will blame Y for the change. I'd like to be able to ignore Y: both the existence of the commit as well as any changes it made. This differs from -S rev-list, which specifies the list of commits to process for the blame. We would still process Y, but just don't let the blame 'stick.' This patch adds the ability for users to ignore a revision with --ignore-rev=rev, which may be repeated. They can specify a set of files of full object names of revs, e.g. SHA-1 hashes, one per line. A single file may be specified with the blame.ignoreRevFile config option or with --ignore-rev-file=file. Both the config option and the command line option may be repeated multiple times. An empty file name "" will clear the list of revs from previously processed files. Config options are processed before command line options. For a typical use case, projects will maintain the file containing revisions for commits that perform mass reformatting, and their users have the option to ignore all of the commits in that file. Additionally, a user can use the --ignore-rev option for one-off investigation. To go back to the example above, X was a substantive change to the function, but not the change the user is interested in. The user inspected X, but wanted to find the previous change to that line - perhaps a commit that introduced that function call. To make this work, we can't simply remove all ignored commits from the rev-list. We need to diff the changes introduced by Y so that we can ignore them. We let the blames get passed to Y, just like when processing normally. When Y is the target, we make sure that Y does not *keep* any blames. Any changes that Y is responsible for get passed to its parent. Note we make one pass through all of the scapegoats (parents) to attempt to pass blame normally; we don't know if we *need* to ignore the commit until we've checked all of the parents. The blame_entry will get passed up the tree until we find a commit that has a diff chunk that affects those lines. One issue is that the ignored commit *did* make some change, and there is no general solution to finding the line in the parent commit that corresponds to a given line in the ignored commit. That makes it hard to attribute a particular line within an ignored commit's diff correctly. For example, the parent of an ignored commit has this, say at line 11: commit-a 11) #include "a.h" commit-b 12) #include "b.h" Commit X, which we will ignore, swaps these lines: commit-X 11) #include "b.h" commit-X 12) #include "a.h" We can pass that blame entry to the parent, but line 11 will be attributed to commit A, even though "include b.h" came from commit B. The blame mechanism will be looking at the parent's view of the file at line number 11. ignore_blame_entry() is set up to allow alternative algorithms for guessing per-line blames. Any line that is not attributed to the parent will continue to be blamed on the ignored commit as if that commit was not ignored. Upcoming patches have the ability to detect these lines and mark them in the blame output. The existing algorithm is simple: blame each line on the corresponding line in the parent's diff chunk. Any lines beyond that stay with the target. For example, the parent of an ignored commit has this, say at line 11: commit-a 11) void new_func_1(void *x, void *y); commit-b 12) void new_func_2(void *x, void *y); commit-c 13) some_line_c commit-d 14) some_line_d After a commit 'X', we have: commit-X 11) void new_func_1(void *x, commit-X 12) void *y); commit-X 13) void new_func_2(void *x, commit-X 14) void *y); commit-c 15) some_line_c commit-d 16) some_line_d Commit X nets two additionally lines: 13 and 14. The current guess_line_blames() algorithm will not attribute these to the parent, whose diff chunk is only two lines - not four. When we ignore with the current algorithm, we get: commit-a 11) void new_func_1(void *x, commit-b 12) void *y); commit-X 13) void new_func_2(void *x, commit-X 14) void *y); commit-c 15) some_line_c commit-d 16) some_line_d Note that line 12 was blamed on B, though B was the commit for new_func_2(), not new_func_1(). Even when guess_line_blames() finds a line in the parent, it may still be incorrect. Signed-off-by: Barret Rhoden <brho@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
129 lines
4.8 KiB
Plaintext
129 lines
4.8 KiB
Plaintext
-b::
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Show blank SHA-1 for boundary commits. This can also
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be controlled via the `blame.blankboundary` config option.
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--root::
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Do not treat root commits as boundaries. This can also be
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controlled via the `blame.showRoot` config option.
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--show-stats::
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Include additional statistics at the end of blame output.
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-L <start>,<end>::
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-L :<funcname>::
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Annotate only the given line range. May be specified multiple times.
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Overlapping ranges are allowed.
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+
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<start> and <end> are optional. ``-L <start>'' or ``-L <start>,'' spans from
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<start> to end of file. ``-L ,<end>'' spans from start of file to <end>.
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+
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include::line-range-format.txt[]
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-l::
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Show long rev (Default: off).
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-t::
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Show raw timestamp (Default: off).
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-S <revs-file>::
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Use revisions from revs-file instead of calling linkgit:git-rev-list[1].
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--reverse <rev>..<rev>::
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Walk history forward instead of backward. Instead of showing
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the revision in which a line appeared, this shows the last
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revision in which a line has existed. This requires a range of
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revision like START..END where the path to blame exists in
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START. `git blame --reverse START` is taken as `git blame
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--reverse START..HEAD` for convenience.
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-p::
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--porcelain::
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Show in a format designed for machine consumption.
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--line-porcelain::
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Show the porcelain format, but output commit information for
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each line, not just the first time a commit is referenced.
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Implies --porcelain.
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--incremental::
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Show the result incrementally in a format designed for
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machine consumption.
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--encoding=<encoding>::
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Specifies the encoding used to output author names
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and commit summaries. Setting it to `none` makes blame
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output unconverted data. For more information see the
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discussion about encoding in the linkgit:git-log[1]
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manual page.
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--contents <file>::
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When <rev> is not specified, the command annotates the
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changes starting backwards from the working tree copy.
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This flag makes the command pretend as if the working
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tree copy has the contents of the named file (specify
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`-` to make the command read from the standard input).
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--date <format>::
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Specifies the format used to output dates. If --date is not
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provided, the value of the blame.date config variable is
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used. If the blame.date config variable is also not set, the
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iso format is used. For supported values, see the discussion
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of the --date option at linkgit:git-log[1].
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--[no-]progress::
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Progress status is reported on the standard error stream
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by default when it is attached to a terminal. This flag
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enables progress reporting even if not attached to a
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terminal. Can't use `--progress` together with `--porcelain`
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or `--incremental`.
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-M[<num>]::
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Detect moved or copied lines within a file. When a commit
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moves or copies a block of lines (e.g. the original file
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has A and then B, and the commit changes it to B and then
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A), the traditional 'blame' algorithm notices only half of
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the movement and typically blames the lines that were moved
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up (i.e. B) to the parent and assigns blame to the lines that
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were moved down (i.e. A) to the child commit. With this
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option, both groups of lines are blamed on the parent by
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running extra passes of inspection.
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+
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<num> is optional but it is the lower bound on the number of
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alphanumeric characters that Git must detect as moving/copying
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within a file for it to associate those lines with the parent
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commit. The default value is 20.
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-C[<num>]::
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In addition to `-M`, detect lines moved or copied from other
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files that were modified in the same commit. This is
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useful when you reorganize your program and move code
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around across files. When this option is given twice,
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the command additionally looks for copies from other
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files in the commit that creates the file. When this
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option is given three times, the command additionally
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looks for copies from other files in any commit.
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+
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<num> is optional but it is the lower bound on the number of
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alphanumeric characters that Git must detect as moving/copying
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between files for it to associate those lines with the parent
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commit. And the default value is 40. If there are more than one
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`-C` options given, the <num> argument of the last `-C` will
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take effect.
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--ignore-rev <rev>::
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Ignore changes made by the revision when assigning blame, as if the
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change never happened. Lines that were changed or added by an ignored
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commit will be blamed on the previous commit that changed that line or
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nearby lines. This option may be specified multiple times to ignore
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more than one revision.
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--ignore-revs-file <file>::
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Ignore revisions listed in `file`, which must be in the same format as an
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`fsck.skipList`. This option may be repeated, and these files will be
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processed after any files specified with the `blame.ignoreRevsFile` config
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option. An empty file name, `""`, will clear the list of revs from
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previously processed files.
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-h::
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Show help message.
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