Submodules: Add the new "ignore" config option for diff and status

The new "ignore" config option controls the default behavior for "git
status" and the diff family. It specifies under what circumstances they
consider submodules as modified and can be set separately for each
submodule.

The command line option "--ignore-submodules=" has been extended to accept
the new parameter "none" for both status and diff.

Users that chose submodules to get rid of long work tree scanning times
might want to set the "dirty" option for those submodules. This brings
back the pre 1.7.0 behavior, where submodule work trees were never
scanned for modifications. By using "--ignore-submodules=none" on the
command line the status and diff commands can be told to do a full scan.

This option can be set to the following values (which have the same name
and meaning as for the "--ignore-submodules" option of status and diff):

"all": All changes to the submodule will be ignored.

"dirty": Only differences of the commit recorded in the superproject and
	the submodules HEAD will be considered modifications, all changes
	to the work tree of the submodule will be ignored. When using this
	value, the submodule will not be scanned for work tree changes at
	all, leading to a performance benefit on large submodules.

"untracked": Only untracked files in the submodules work tree are ignored,
	a changed HEAD and/or modified files in the submodule will mark it
	as modified.

"none" (which is the default): Either untracked or modified files in a
	submodules work tree or a difference between the subdmodules HEAD
	and the commit recorded in the superproject will make it show up
	as changed. This value is added as a new parameter for the
	"--ignore-submodules" option of the diff family and "git status"
	so the user can override the settings in the configuration.

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

1 files changed, 29 insertions, 6 deletions

diff --git a/diff.c b/diff.c
index 17873f3d9e..8206047314 100644
--- a/diff.c
+++ b/diff.c
@@ -141,6 +141,9 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!prefixcmp(var, "submodule."))
+		return parse_submodule_config_option(var, value);
+
 	return git_color_default_config(var, value, cb);
 }
 
@@ -3166,11 +3169,13 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		DIFF_OPT_SET(options, ALLOW_TEXTCONV);
 	else if (!strcmp(arg, "--no-textconv"))
 		DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
-	else if (!strcmp(arg, "--ignore-submodules"))
+	else if (!strcmp(arg, "--ignore-submodules")) {
+		DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
 		handle_ignore_submodules_arg(options, "all");
-	else if (!prefixcmp(arg, "--ignore-submodules="))
+	} else if (!prefixcmp(arg, "--ignore-submodules=")) {
+		DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
 		handle_ignore_submodules_arg(options, arg + 20);
-	else if (!strcmp(arg, "--submodule"))
+	} else if (!strcmp(arg, "--submodule"))
 		DIFF_OPT_SET(options, SUBMODULE_LOG);
 	else if (!prefixcmp(arg, "--submodule=")) {
 		if (!strcmp(arg + 12, "log"))
@@ -4103,6 +4108,24 @@ int diff_result_code(struct diff_options *opt, int status)
 	return result;
 }
 
+/*
+ * Shall changes to this submodule be ignored?
+ *
+ * Submodule changes can be configured to be ignored separately for each path,
+ * but that configuration can be overridden from the command line.
+ */
+static int is_submodule_ignored(const char *path, struct diff_options *options)
+{
+	int ignored = 0;
+	unsigned orig_flags = options->flags;
+	if (!DIFF_OPT_TST(options, OVERRIDE_SUBMODULE_CONFIG))
+		set_diffopt_flags_from_submodule_config(options, path);
+	if (DIFF_OPT_TST(options, IGNORE_SUBMODULES))
+		ignored = 1;
+	options->flags = orig_flags;
+	return ignored;
+}
+
 void diff_addremove(struct diff_options *options,
 		    int addremove, unsigned mode,
 		    const unsigned char *sha1,
@@ -4110,7 +4133,7 @@ void diff_addremove(struct diff_options *options,
 {
 	struct diff_filespec *one, *two;
 
-	if (DIFF_OPT_TST(options, IGNORE_SUBMODULES) && S_ISGITLINK(mode))
+	if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
 		return;
 
 	/* This may look odd, but it is a preparation for
@@ -4157,8 +4180,8 @@ void diff_change(struct diff_options *options,
 {
 	struct diff_filespec *one, *two;
 
-	if (DIFF_OPT_TST(options, IGNORE_SUBMODULES) && S_ISGITLINK(old_mode)
-			&& S_ISGITLINK(new_mode))
+	if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
+	    is_submodule_ignored(concatpath, options))
 		return;
 
 	if (DIFF_OPT_TST(options, REVERSE_DIFF)) {