test-dump-untracked-cache: don't modify the untracked cache

To correctly perform its testing function,
test-dump-untracked-cache should not change the state of the
untracked cache in the index.

As a previous patch makes read_index_from() change the state of
the untracked cache and as test-dump-untracked-cache indirectly
calls this function, we need a mechanism to prevent
read_index_from() from changing the untracked cache state when
it's called from test-dump-untracked-cache.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -1604,6 +1604,13 @@ extern int git_config_get_maybe_bool(const char *key, int *dest);
 extern int git_config_get_pathname(const char *key, const char **dest);
 extern int git_config_get_untracked_cache(void);
 
+/*
+ * This is a hack for test programs like test-dump-untracked-cache to
+ * ensure that they do not modify the untracked cache when reading it.
+ * Do not use it otherwise!
+ */
+extern int ignore_untracked_cache_config;
+
 struct key_value_info {
 	const char *filename;
 	int linenr;

config.c

@@ -1599,6 +1599,10 @@ int git_config_get_untracked_cache(void)
 	int val = -1;
 	const char *v;
 
+	/* Hack for test programs like test-dump-untracked-cache */
+	if (ignore_untracked_cache_config)
+		return -1;
+
 	if (!git_config_get_maybe_bool("core.untrackedcache", &val))
 		return val;
 

environment.c

@@ -87,6 +87,13 @@ int auto_comment_line_char;
 /* Parallel index stat data preload? */
 int core_preload_index = 1;
 
+/*
+ * This is a hack for test programs like test-dump-untracked-cache to
+ * ensure that they do not modify the untracked cache when reading it.
+ * Do not use it otherwise!
+ */
+int ignore_untracked_cache_config;
+
 /* This is set by setup_git_dir_gently() and/or git_default_config() */
 char *git_work_tree_cfg;
 static char *work_tree;

test-dump-untracked-cache.c

@@ -44,6 +44,10 @@ int main(int ac, char **av)
 {
 	struct untracked_cache *uc;
 	struct strbuf base = STRBUF_INIT;
+
+	/* Hack to avoid modifying the untracked cache when we read it */
+	ignore_untracked_cache_config = 1;
+
 	setup_git_directory();
 	if (read_cache() < 0)
 		die("unable to read index file");