Add the 'diff.ignoreSubmodules' config setting

When you have a lot of submodules checked out, the time penalty to check
for dirty submodules can easily imply a multiplication of the total time
by the factor 20. This makes the difference between almost instantaneous
(< 2 seconds) and unbearably slow (> 50 seconds) here, since the disk
caches are constantly overloaded.

To this end, the submodule.*.ignore config option was introduced, but it
is per-submodule.

This commit introduces a global config setting to set a default
(porcelain) value for the --ignore-submodules option, keeping the
default at 'none'. It can be overridden by the submodule.*.ignore
setting and by the --ignore-submodules option.

Incidentally, this commit fixes an issue with the overriding logic:
multiple --ignore-submodules options would not clear the previously
set flags.

While at it, fix a typo in the documentation for submodule.*.ignore.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/diff.c b/diff.c
index 8206047314..1ddfdfbc2c 100644
--- a/diff.c
+++ b/diff.c
@@ -31,6 +31,7 @@ static const char *external_diff_cmd_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
 static int diff_no_prefix;
+static struct diff_options default_diff_options;
 
 static char diff_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_RESET,
@@ -107,6 +108,9 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 	if (!strcmp(var, "diff.wordregex"))
 		return git_config_string(&diff_word_regex_cfg, var, value);
 
+	if (!strcmp(var, "diff.ignoresubmodules"))
+		handle_ignore_submodules_arg(&default_diff_options, value);
+
 	return git_diff_basic_config(var, value, cb);
 }
 
@@ -2816,7 +2820,7 @@ static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
 
 void diff_setup(struct diff_options *options)
 {
-	memset(options, 0, sizeof(*options));
+	memcpy(options, &default_diff_options, sizeof(*options));
 	memset(&diff_queued_diff, 0, sizeof(diff_queued_diff));
 
 	options->file = stdout;