[RFC/PATCH 3/3] Teach --dirstat to not completely ignore rearranged lines
- From
Johan Herland <johan@herland.net>
- Date
- Apr 8, 2011, 14:55 UTC
- Message-ID
- <201104081655.38075.johan@herland.net>
- In-Reply-To
- <201104081646.35750.johan@herland.net>
Currently, the --dirstat analysis fails to detect some kinds of changes. For example, rearranging lines in a file causes the "damage" calculated by show_dirstat() to be 0. However, when we process the diff queue in show_dirstat(), we already now that there should be at least _some_ damage assigned to each entry, because truly _unchanged_ entries are simply not present in the diff queue.
This patch teaches show_dirstat() to assign a minimum amount of damage (== 1) to entries for which the analysis otherwise yields zero damage. Obviously this is not a complete fix, but it's at least better to underrepresent these changes, rather than simply pretending that they don't exist.
Signed-off-by: Johan Herland <johan@herland.net> ---
This is a somewhat quick and ugly solution to make --dirstat at least show _something_ for changes that consist solely of rearranging lines in a file. Sure, those changes would be thoroughly underrepresented by --dirstat (probably falling below the default 3% threshold in many cases), but I figure it's better to underrepresent them rather than ignoring them completely.
As with 2/3, this patch also relies on the assumption that the diff queue never contains entries that should be considered "unchanged" by --dirstat.
Documentation/diff-options.txt | 4 ++-- diff.c | 8 ++++++++ t/t4013-diff-various.sh | 2 -- t/t4013/diff.diff_--dirstat_initial_rearrange | 1 + 4 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt index 25e48c4..61a8409 100644 --- a/Documentation/diff-options.txt +++ b/Documentation/diff-options.txt @@ -75,8 +75,8 @@ endif::git-format-patch[] + Note that `--dirstat` does not use the regular diff machinery to calculate the changes (rather it is based on the rename detection machinery). Therefore, -`--dirstat` may skip some changes that `--stat` does not skip. For example, -rearranging the lines in a file will not be detected by `--dirstat`. +`--dirstat` will count some changes differently than `--stat`. For example, +rearranged lines in a file will be underrepresented by `--dirstat`. --dirstat-by-file[=<limit>]:: Same as `--dirstat`, but counts changed files instead of lines. diff --git a/diff.c b/diff.c index 28d9293..0d82082 100644 --- a/diff.c +++ b/diff.c @@ -1578,8 +1578,16 @@ static void show_dirstat(struct diff_options *options) * Original minus copied is the removed material, * added is the new material. They are both damages * made to the preimage. + * If the resulting damage is zero, we know that + * diffcore_count_changes() considers the two entries + * to be identical, but since they are in the diff + * queue at all, we now that there must have been + * _some_ kind of change, so we force all entries to + * have at least a minimum of damage. */ damage = (p->one->size - copied) + added; + if (!damage) + damage = 1; found_damage: ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc); diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh index e8240f2..93a6f20 100755 --- a/t/t4013-diff-various.sh +++ b/t/t4013-diff-various.sh @@ -300,9 +300,7 @@ diff --no-index --name-status -- dir2 dir diff --no-index dir dir3 diff master master^ side diff --dirstat master~1 master~2 -# --dirstat does NOT pick up changes that simply rearrange existing lines diff --dirstat initial rearrange -# ...but --dirstat-by-file DOES pick up rearranged lines diff --dirstat-by-file initial rearrange EOF diff --git a/t/t4013/diff.diff_--dirstat_initial_rearrange b/t/t4013/diff.diff_--dirstat_initial_rearrange index fb2e17d..5fb02c1 100644 --- a/t/t4013/diff.diff_--dirstat_initial_rearrange +++ b/t/t4013/diff.diff_--dirstat_initial_rearrange @@ -1,2 +1,3 @@ $ git diff --dirstat initial rearrange + 100.0% dir/ $
-- 1.7.5.rc1