Add optional parameters to the diff option "--ignore-submodules"

In some use cases it is not desirable that the diff family considers
submodules that only contain untracked content as dirty. This may happen
e.g. when the submodule is not under the developers control and not all
build generated files have been added to .gitignore by the upstream
developers. Using the "untracked" parameter for the "--ignore-submodules"
option disables checking for untracked content and lets git diff report
them as changed only when they have new commits or modified content.

Sometimes it is not wanted to have submodules show up as changed when they
just contain changes to their work tree. An example for that are scripts
which just want to check for submodule commits while ignoring any changes
to the work tree. Also users having large submodules known not to change
might want to use this option, as the - sometimes substantial - time it
takes to scan the submodule work tree(s) is saved.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/diff-options.txt

@@ -288,8 +288,14 @@ endif::git-format-patch[]
 --no-ext-diff::
 	Disallow external diff drivers.
 
---ignore-submodules::
-	Ignore changes to submodules in the diff generation.
+--ignore-submodules[=<when>]::
+	Ignore changes to submodules in the diff generation. <when> can be
+	either "untracked", "dirty" or "all", which is the default. When
+	"untracked" is used submodules are not considered dirty when they only
+	contain untracked content (but they are still scanned for modified
+	content). Using "dirty" ignores all changes to the work tree of submodules,
+	only changes to the commits stored in the superproject are shown (this was
+	the behavior until 1.7.0). Using "all" hides all changes to submodules.
 
 --src-prefix=<prefix>::
 	Show the given source prefix instead of "a/".

diff-lib.c

@@ -70,6 +70,7 @@ static int match_stat_with_submodule(struct diff_options *diffopt,
 	int changed = ce_match_stat(ce, st, ce_option);
 	if (S_ISGITLINK(ce->ce_mode)
 	    && !DIFF_OPT_TST(diffopt, IGNORE_SUBMODULES)
+	    && !DIFF_OPT_TST(diffopt, IGNORE_DIRTY_SUBMODULES)
 	    && (!changed || DIFF_OPT_TST(diffopt, DIRTY_SUBMODULES))) {
 		*dirty_submodule = is_submodule_modified(ce->name, DIFF_OPT_TST(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES));
 	}

diff.c

@@ -2867,7 +2867,16 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
 	else if (!strcmp(arg, "--ignore-submodules"))
 		DIFF_OPT_SET(options, IGNORE_SUBMODULES);
-	else if (!strcmp(arg, "--submodule"))
+	else if (!prefixcmp(arg, "--ignore-submodules=")) {
+		if (!strcmp(arg + 20, "all"))
+			DIFF_OPT_SET(options, IGNORE_SUBMODULES);
+		else if (!strcmp(arg + 20, "untracked"))
+			DIFF_OPT_SET(options, IGNORE_UNTRACKED_IN_SUBMODULES);
+		else if (!strcmp(arg + 20, "dirty"))
+			DIFF_OPT_SET(options, IGNORE_DIRTY_SUBMODULES);
+		else
+			die("bad --ignore-submodules argument: %s", arg + 20);
+	} else if (!strcmp(arg, "--submodule"))
 		DIFF_OPT_SET(options, SUBMODULE_LOG);
 	else if (!prefixcmp(arg, "--submodule=")) {
 		if (!strcmp(arg + 12, "log"))

diff.h

@@ -71,6 +71,7 @@ typedef void (*diff_format_fn_t)(struct diff_queue_struct *q,
 #define DIFF_OPT_SUBMODULE_LOG       (1 << 23)
 #define DIFF_OPT_DIRTY_SUBMODULES    (1 << 24)
 #define DIFF_OPT_IGNORE_UNTRACKED_IN_SUBMODULES (1 << 25)
+#define DIFF_OPT_IGNORE_DIRTY_SUBMODULES (1 << 26)
 
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_SET(opts, flag)    ((opts)->flags |= DIFF_OPT_##flag)

t/t4027-diff-submodule.sh

@@ -103,9 +103,17 @@ test_expect_success 'git diff HEAD with dirty submodule (work tree, refs match)'
 	git diff HEAD >actual &&
 	sed -e "1,/^@@/d" actual >actual.body &&
 	expect_from_to >expect.body $subprev $subprev-dirty &&
-	test_cmp expect.body actual.body
+	test_cmp expect.body actual.body &&
+	git diff --ignore-submodules HEAD >actual2 &&
+	echo -n "" | test_cmp - actual2 &&
+	git diff --ignore-submodules=untracked HEAD >actual3 &&
+	sed -e "1,/^@@/d" actual3 >actual3.body &&
+	expect_from_to >expect.body $subprev $subprev-dirty &&
+	test_cmp expect.body actual3.body &&
+	git diff --ignore-submodules=dirty HEAD >actual4 &&
+	echo -n "" | test_cmp - actual4
 '
-
+test_done
 test_expect_success 'git diff HEAD with dirty submodule (index, refs match)' '
 	(
 		cd sub &&
@@ -129,7 +137,13 @@ test_expect_success 'git diff HEAD with dirty submodule (untracked, refs match)'
 	git diff HEAD >actual &&
 	sed -e "1,/^@@/d" actual >actual.body &&
 	expect_from_to >expect.body $subprev $subprev-dirty &&
-	test_cmp expect.body actual.body
+	test_cmp expect.body actual.body &&
+	git diff --ignore-submodules=all HEAD >actual2 &&
+	echo -n "" | test_cmp - actual2 &&
+	git diff --ignore-submodules=untracked HEAD >actual3 &&
+	echo -n "" | test_cmp - actual3 &&
+	git diff --ignore-submodules=dirty HEAD >actual4 &&
+	echo -n "" | test_cmp - actual4
 '
 
 test_expect_success 'git diff (empty submodule dir)' '

t/t4041-diff-submodule-option.sh

@@ -205,6 +205,21 @@ Submodule sm1 contains untracked content
 EOF
 "
 
+test_expect_success 'submodule contains untracked content (untracked ignored)' "
+	git diff-index -p --ignore-submodules=untracked --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
+test_expect_success 'submodule contains untracked content (dirty ignored)' "
+	git diff-index -p --ignore-submodules=dirty --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
+test_expect_success 'submodule contains untracked content (all ignored)' "
+	git diff-index -p --ignore-submodules=all --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
 test_expect_success 'submodule contains untracked and modifed content' "
 	echo new > sm1/foo6 &&
 	git diff-index -p --submodule=log HEAD >actual &&
@@ -214,6 +229,26 @@ Submodule sm1 contains modified content
 EOF
 "
 
+test_expect_success 'submodule contains untracked and modifed content (untracked ignored)' "
+	echo new > sm1/foo6 &&
+	git diff-index -p --ignore-submodules=untracked --submodule=log HEAD >actual &&
+	diff actual - <<-EOF
+Submodule sm1 contains modified content
+EOF
+"
+
+test_expect_success 'submodule contains untracked and modifed content (dirty ignored)' "
+	echo new > sm1/foo6 &&
+	git diff-index -p --ignore-submodules=dirty --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
+test_expect_success 'submodule contains untracked and modifed content (all ignored)' "
+	echo new > sm1/foo6 &&
+	git diff-index -p --ignore-submodules --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
 test_expect_success 'submodule contains modifed content' "
 	rm -f sm1/new-file &&
 	git diff-index -p --submodule=log HEAD >actual &&
@@ -242,6 +277,27 @@ Submodule sm1 $head6..$head8:
 EOF
 "
 
+test_expect_success 'modified submodule contains untracked content (untracked ignored)' "
+	git diff-index -p --ignore-submodules=untracked --submodule=log HEAD >actual &&
+	diff actual - <<-EOF
+Submodule sm1 $head6..$head8:
+  > change
+EOF
+"
+
+test_expect_success 'modified submodule contains untracked content (dirty ignored)' "
+	git diff-index -p --ignore-submodules=dirty --submodule=log HEAD >actual &&
+	diff actual - <<-EOF
+Submodule sm1 $head6..$head8:
+  > change
+EOF
+"
+
+test_expect_success 'modified submodule contains untracked content (all ignored)' "
+	git diff-index -p --ignore-submodules=all --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
 test_expect_success 'modified submodule contains untracked and modifed content' "
 	echo modification >> sm1/foo6 &&
 	git diff-index -p --submodule=log HEAD >actual &&
@@ -253,6 +309,31 @@ Submodule sm1 $head6..$head8:
 EOF
 "
 
+test_expect_success 'modified submodule contains untracked and modifed content (untracked ignored)' "
+	echo modification >> sm1/foo6 &&
+	git diff-index -p --ignore-submodules=untracked --submodule=log HEAD >actual &&
+	diff actual - <<-EOF
+Submodule sm1 contains modified content
+Submodule sm1 $head6..$head8:
+  > change
+EOF
+"
+
+test_expect_success 'modified submodule contains untracked and modifed content (dirty ignored)' "
+	echo modification >> sm1/foo6 &&
+	git diff-index -p --ignore-submodules=dirty --submodule=log HEAD >actual &&
+	diff actual - <<-EOF
+Submodule sm1 $head6..$head8:
+  > change
+EOF
+"
+
+test_expect_success 'modified submodule contains untracked and modifed content (all ignored)' "
+	echo modification >> sm1/foo6 &&
+	git diff-index -p --ignore-submodules --submodule=log HEAD >actual &&
+	echo -n '' | diff actual -
+"
+
 test_expect_success 'modified submodule contains modifed content' "
 	rm -f sm1/new-file &&
 	git diff-index -p --submodule=log HEAD >actual &&