This patch fixes a corner case where diff-highlight may
scramble some diffs when combined with --graph.
Commit 7e4ffb4c17 (diff-highlight: add support for --graph
output, 2016-08-29) taught diff-highlight to skip past the
graph characters at the start of each line with this regex:
($COLOR?\|$COLOR?\s+)*
I.e., any series of pipes separated by and followed by
arbitrary whitespace. We need to match more than just a
single space because the commit in question may be indented
to accommodate other parts of the graph drawing. E.g.:
* commit 1234abcd
| ...
| diff --git ...
has only a single space, but for the last commit before a
fork:
| | |
| * | commit 1234abcd
| |/ ...
| | diff --git
the diff lines have more spaces between the pipes and the
start of the diff.
However, when we soak up all of those spaces with the
$GRAPH regex, we may accidentally include the leading space
for a context line. That means we may consider the actual
contents of a context line as part of the diff syntax. In
other words, something like this:
normal context line
-old line
+new line
-this is a context line with a leading dash
would cause us to see that final context line as a removal
line, and we'd end up showing the hunk in the wrong order:
normal context line
-old line
-this is a context line with a leading dash
+new line
Instead, let's a be a little more clever about parsing the
graph. We'll look for the actual "*" line that marks the
start of a commit, and record the indentation we see there.
Then we can skip past that indentation when checking whether
the line is a hunk header, removal, addition, etc.
There is one tricky thing: the indentation in bytes may be
different for various lines of the graph due to coloring.
E.g., the "*" on a commit line is generally shown without
color, but on the actual diff lines, it will be replaced
with a colorized "|" character, adding several bytes. We
work around this here by counting "visible" bytes. This is
unfortunately a bit more expensive, making us about twice as
slow to handle --graph output. But since this is meant to be
used interactively anyway, it's tolerably fast (and the
non-graph case is unaffected).
One alternative would be to search for hunk header lines and
use their indentation (since they'd have the same colors as
the diff lines which follow). But that just opens up
different corner cases. If we see:
| | @@ 1,2 1,3 @@
we cannot know if this is a real diff that has been
indented due to the graph, or if it's a context line that
happens to look like a diff header. We can only be sure of
the indent on the "*" lines, since we know those don't
contain arbitrary data (technically the user could include a
bunch of extra indentation via --format, but that's rare
enough to disregard).
Reported-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our tests send git's output directly to files or pipes, so
there will never be any color. Let's do at least one --color
test to make sure that we can handle this case (which we
currently can, but will be an easy thing to mess up when we
touch the graph code in a future patch).
We'll just cover the --graph case, since this is much more
complex than the earlier cases (i.e., if it manages to
highlight, then the non-graph case definitely would).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The graph test in t9400 covers the case of two simultaneous
branches, but all of the commits during this time are on the
right-hand branch. So we test a graph structure like:
| |
| * commit ...
| |
but we never see the reverse, a commit on the left-hand
branch:
| |
* | commit ...
| |
Since this is an easy thing to get wrong when touching the
graph-matching code, let's cover it by adding one more
commit with its timestamp interleaved with the other branch.
Note that we need to pass --date-order to convince Git to
show it this way (since --topo-order tries to keep lines of
history separate).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We generate a bunch of one-line files whose contents match
their names, and then generate our commits by cat-ing those
files. Let's just echo the contents directly, which saves
some processes.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The exact ordering output by Git may depend on the commit
timestamps, so let's make sure they're actually
monotonically increasing, and not all the same (or worse,
subject to how long the test script takes to run).
Let's use test_tick to make sure this is stable. Note that
we actually have to rearrange the order of the branches to
match the expected graph structure (which means that
previously we might racily have been testing a slightly
different output, though the test is written in such a way
that we'd still pass).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We actually branch "A" off of "D". The sample "--graph"
output is right, but the left-to-right diagram is
misleading. Let's fix it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The algorithm in diff-highlight only understands how to look
at two sides of a diff; it cannot correctly handle combined
diffs with multiple preimages. Often highlighting does not
trigger at all for these diffs because the line counts do
not match up. E.g., if we see:
- ours
-theirs
++resolved
we would not bother highlighting; it naively looks like a
single line went away, and then a separate hunk added
another single line.
But of course there are exceptions. E.g., if the other side
deleted the line, we might see:
- ours
++resolved
which looks like we dropped " ours" and added "+resolved".
This is only a small highlighting glitch (we highlight the
space and the "+" along with the content), but it's also the
tip of the iceberg. Even if we learned to find the true
content here (by noticing we are in a 3-way combined diff
and marking _two_ characters from the front of the line as
uninteresting), there are other more complicated cases where
we really do need to handle a 3-way hunk.
Let's just punt for now; we can recognize combined diffs by
the presence of extra "@" symbols in the hunk header, and
treat them as non-diff content.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that we have a test suite for diff highlight, we can
show off the improvements from 8d00662 (diff-highlight: do
not split multibyte characters, 2015-04-03).
While we're at it, we can also add another case that
_doesn't_ work: combining code points are treated as their
own unit, which means that we may stick colors between them
and the character they are modifying (with the result that
the color is not shown in an xterm, though it's possible
that other terminals err the other way, and show the color
but not the accent). There's no fix here, but let's
document it as a failure.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
