[PATCH v5 5/6] blame: add a config option to mark ignored lines

[Barret Rhoden <brho@google.com>]

When ignoring commits, the commit that is blamed might not be
responsible for the change.  Users might want to know when a particular
line has a potentially inaccurate blame.

This patch adds a config option to identify these lines by specifying
blame.markIgnoredFiles.  When this option is set, each blame line is
marked with an '*'.  For example:

278b6158d6fdb (Barret Rhoden  2016-04-11 13:57:54 -0400 26)

appears as:

*278b6158d6fd (Barret Rhoden  2016-04-11 13:57:54 -0400 26)

where the '*' is placed before the commit, and the hash has one fewer
characters.

Signed-off-by: Barret Rhoden <brho@google.com>
---
 Documentation/config/blame.txt |  4 ++++
 blame.c                        |  4 ++++
 blame.h                        |  1 +
 builtin/blame.c                |  9 +++++++++
 t/t8013-blame-ignore-revs.sh   | 33 +++++++++++++++++++++++++++++++++
 5 files changed, 51 insertions(+)

diff --git a/Documentation/config/blame.txt b/Documentation/config/blame.txt
index 4da2788f306d..9f7f0fcf42c9 100644
--- a/Documentation/config/blame.txt
+++ b/Documentation/config/blame.txt
@@ -26,3 +26,7 @@ blame.ignoreRevsFile::
 	`#` are ignored.  This option may be repeated multiple times.  Empty
 	file names will reset the list of ignored revisions.  This option will
 	be handled before the command line option `--ignore-revs-file`.
+
+blame.markIgnoredLines::
+	Mark lines that were changed by an ignored revision with a '*' in the
+	output of linkgit:git-blame[1].
diff --git a/blame.c b/blame.c
index e0612ac34ba7..c06cbd906658 100644
--- a/blame.c
+++ b/blame.c
@@ -515,6 +515,7 @@ void blame_coalesce(struct blame_scoreboard *sb)
 	for (ent = sb->ent; ent && (next = ent->next); ent = next) {
 		if (ent->suspect == next->suspect &&
 		    ent->s_lno + ent->num_lines == next->s_lno &&
+		    ent->ignored == next->ignored &&
 		    ent->unblamable == next->unblamable) {
 			ent->num_lines += next->num_lines;
 			ent->next = next->next;
@@ -767,6 +768,7 @@ static void split_overlap(struct blame_entry *split,
 	int chunk_end_lno;
 	memset(split, 0, sizeof(struct blame_entry [3]));
 
+	split[0].ignored = split[1].ignored = split[2].ignored = e->ignored;
 	split[0].unblamable = e->unblamable;
 	split[1].unblamable = e->unblamable;
 	split[2].unblamable = e->unblamable;
@@ -891,6 +893,7 @@ static struct blame_entry *split_blame_at(struct blame_entry *e, int len,
 	struct blame_entry *n = xcalloc(1, sizeof(struct blame_entry));
 
 	n->suspect = new_suspect;
+	n->ignored = e->ignored;
 	n->unblamable = e->unblamable;
 	n->lno = e->lno + len;
 	n->s_lno = e->s_lno + len;
@@ -954,6 +957,7 @@ static void ignore_blame_entry(struct blame_entry *e,
 	struct blame_line_tracker *line_blames;
 	int entry_len, nr_lines;
 
+	e->ignored = 1;
 	line_blames = xcalloc(sizeof(struct blame_line_tracker),
 			      e->num_lines);
 	guess_line_blames(e, parent, target, offset, delta, line_blames);
diff --git a/blame.h b/blame.h
index 93780b01504c..f7755920c90d 100644
--- a/blame.h
+++ b/blame.h
@@ -94,6 +94,7 @@ struct blame_entry {
 	 * scanning the lines over and over.
 	 */
 	unsigned score;
+	int ignored;
 	int unblamable;
 };
 
diff --git a/builtin/blame.c b/builtin/blame.c
index 5f38e9dccddd..46d96905de75 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -53,6 +53,7 @@ static int show_progress;
 static char repeated_meta_color[COLOR_MAXLEN];
 static int coloring_mode;
 static struct string_list ignore_revs_file_list = STRING_LIST_INIT_NODUP;
+static int mark_ignored_lines;
 
 static struct date_mode blame_date_mode = { DATE_ISO8601 };
 static size_t blame_date_width;
@@ -482,6 +483,10 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 			}
 		}
 
+		if (mark_ignored_lines && ent->ignored) {
+			length--;
+			putchar('*');
+		}
 		if (ent->unblamable)
 			memset(hex, '0', length);
 		printf("%.*s", length, hex);
@@ -710,6 +715,10 @@ static int git_blame_config(const char *var, const char *value, void *cb)
 		string_list_insert(&ignore_revs_file_list, str);
 		return 0;
 	}
+	if (!strcmp(var, "blame.markignoredlines")) {
+		mark_ignored_lines = git_config_bool(var, value);
+		return 0;
+	}
 	if (!strcmp(var, "color.blame.repeatedlines")) {
 		if (color_parse_mem(value, strlen(value), repeated_meta_color))
 			warning(_("invalid color '%s' in color.blame.repeatedLines"),
diff --git a/t/t8013-blame-ignore-revs.sh b/t/t8013-blame-ignore-revs.sh
index df4993f98682..c4cd9a6c54be 100755
--- a/t/t8013-blame-ignore-revs.sh
+++ b/t/t8013-blame-ignore-revs.sh
@@ -123,6 +123,39 @@ test_expect_success bad_files_and_revs '
 	test_i18ngrep "Invalid object name: NOREV" err
 	'
 
+# Commit Z will touch the first two lines.  Y touched all four.
+# 	A--B--X--Y--Z
+# The blame output when ignoring Z should be:
+# ^Y ... 1)
+# ^Y ... 2)
+# Y  ... 3)
+# Y  ... 4)
+# We're checking only the first character
+test_expect_success mark_ignored_lines '
+	git config --add blame.markIgnoredLines true &&
+
+	test_write_lines line-one-Z line-two-Z y3 y4 >file &&
+	git add file &&
+	test_tick &&
+	git commit -m Z &&
+	git tag Z &&
+
+	git blame --ignore-rev Z file >blame_raw &&
+	echo "*" >expect &&
+
+	sed -n "1p" blame_raw | cut -c1 >actual &&
+	test_cmp expect actual &&
+
+	sed -n "2p" blame_raw | cut -c1 >actual &&
+	test_cmp expect actual &&
+
+	sed -n "3p" blame_raw | cut -c1 >actual &&
+	! test_cmp expect actual &&
+
+	sed -n "4p" blame_raw | cut -c1 >actual &&
+	! test_cmp expect actual
+	'
+
 # Resetting the repo and creating:
 #
 # A--B--M
-- 
2.21.0.392.gf8f6787159e-goog