Merge branch 'np/blame-ignore-revs-file-may-be-optional' into seen

When the file named by blame.ignoreRevsFile configuration variable
does not exist, it causes "git blame" to die.  Sometimes, it is
useful if the files named by configuration variables can be made
optional (it would allow ~/.gitconfig to give a filename, and make
it effective only in repositories that have a file with that name).

This uses an extra variable that marks that the variable is
optional.  Yet another alternative is being discussed to define
syntax for "optional" filename values, so that the same mechanism
can be used for not just blame.ignoreRevsFile but other filenames.

Queued just as a reminder of the theme.

* np/blame-ignore-revs-file-may-be-optional:
  blame: add config `blame.ignoreRevsFileIsOptional`

Author: gitster

Documentation/blame-options.txt

@@ -134,7 +134,8 @@ take effect.
 	`fsck.skipList`.  This option may be repeated, and these files will be
 	processed after any files specified with the `blame.ignoreRevsFile` config
 	option.  An empty file name, `""`, will clear the list of revs from
-	previously processed files.
+	previously processed files. If `blame.ignoreRevsFileIsOptional` is true,
+	missing files will be silently ignored.
 
 -h::
 	Show help message.

Documentation/config/blame.txt

@@ -27,6 +27,11 @@ blame.ignoreRevsFile::
 	file names will reset the list of ignored revisions.  This option will
 	be handled before the command line option `--ignore-revs-file`.
 
+blame.ignoreRevsFileIsOptional::
+	Silently skip missing files specified by ignoreRevsFile or the command line
+	option `--ignore-revs-file`. If unset, or set to false, missing files will
+	cause a nonrecoverable error.
+
 blame.markUnblamableLines::
 	Mark lines that were changed by an ignored revision that we could not
 	attribute to another commit with a '*' in the output of

builtin/blame.c

@@ -56,6 +56,7 @@ static int coloring_mode;
 static struct string_list ignore_revs_file_list = STRING_LIST_INIT_NODUP;
 static int mark_unblamable_lines;
 static int mark_ignored_lines;
+static int ignorerevsfileisoptional;
 
 static struct date_mode blame_date_mode = { DATE_ISO8601 };
 static size_t blame_date_width;
@@ -715,6 +716,9 @@ 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.ignorerevsfileisoptional")) {
+		ignorerevsfileisoptional = git_config_bool(var, value);
+	}
 	if (!strcmp(var, "blame.markunblamablelines")) {
 		mark_unblamable_lines = git_config_bool(var, value);
 		return 0;
@@ -835,7 +839,8 @@ static void build_ignorelist(struct blame_scoreboard *sb,
 	for_each_string_list_item(i, ignore_revs_file_list) {
 		if (!strcmp(i->string, ""))
 			oidset_clear(&sb->ignore_list);
-		else
+		/* skip non-existent files if ignorerevsfileisoptional is set */
+		else if (!ignorerevsfileisoptional || file_exists(i->string))
 			oidset_parse_file_carefully(&sb->ignore_list, i->string,
 						    peel_to_commit_oid, sb);
 	}

t/t8013-blame-ignore-revs.sh

@@ -127,18 +127,24 @@ test_expect_success override_ignore_revs_file '
 	grep -E "^[0-9a-f]+ [0-9]+ 2" blame_raw | sed -e "s/ .*//" >actual &&
 	test_cmp expect actual
 	'
-test_expect_success bad_files_and_revs '
+test_expect_success bad_revs '
 	test_must_fail git blame file --ignore-rev NOREV 2>err &&
 	test_i18ngrep "cannot find revision NOREV to ignore" err &&
 
-	test_must_fail git blame file --ignore-revs-file NOFILE 2>err &&
-	test_i18ngrep "could not open.*: NOFILE" err &&
-
 	echo NOREV >ignore_norev &&
 	test_must_fail git blame file --ignore-revs-file ignore_norev 2>err &&
 	test_i18ngrep "invalid object name: NOREV" err
 '
 
+# Non-existent ignore-revs-file should fail unless
+# blame.ignoreRevsFileIsOptional is set
+test_expect_success bad_file '
+	test_must_fail git blame file --ignore-revs-file NOFILE &&
+
+	git config --add blame.ignorerevsfileisoptional true &&
+	git blame file --ignore-revs-file NOFILE
+'
+
 # For ignored revs that have added 'unblamable' lines, mark those lines with a
 # '*'
 # 	A--B--X--Y