Fix some diff ignores and submodule dirty workdir

This started out trying to look at the problems from issue #1425
and gradually grew to a broader set of fixes.  There are two core
things fixed here:

1. When you had an ignore like "/bin" which is rooted at the top
   of your tree, instead of immediately adding the "bin/" entry
   as an ignored item in the diff, we were returning all of the
   direct descendants of the directory as ignored items.  This
   changes things to immediately ignore the directory.  Note that
   this effects the behavior in test_status_ignore__subdirectories
   so that we no longer exactly match core gits ignore behavior,
   but the new behavior probably makes more sense (i.e. we now
   will include an ignored directory inside an untracked directory
   that we previously would have left off).
2. When a submodule only contained working directory changes, the
   diff code was always considering it unmodified which was just
   an outright bug. The HEAD SHA of the submodule matches the SHA
   in the parent repo index, and since the SHAs matches, the diff
   code was overwriting the actual status with UNMODIFIED.

These fixes broke existing tests test_diff_workdir__submodules and
test_status_ignore__subdirectories but looking it over, I actually
think the new results are correct and the old results were wrong.
@nulltoken had actually commented on the subdirectory ignore issue
previously.

I also included in the tests some debugging versions of the
shared iteration callback routines that print status or diff
information.  These aren't used actively in the tests, but can be
quickly swapped in to test code to give a better picture of what
is being scanned in some of the complex test scenarios.

src/diff.c

@@ -572,7 +572,13 @@ static int maybe_modified(
 				return -1;
 			use_noid = &noid;
 		}
-		if (omode == nmode && git_oid_equal(&oitem->oid, use_noid))
+
+		/* if oid matches, then mark unmodified (except submodules, where
+		 * the filesystem content may be modified even if the oid still
+		 * matches between the index and the workdir HEAD)
+		 */
+		if (omode == nmode && !S_ISGITLINK(omode) &&
+			git_oid_equal(&oitem->oid, use_noid))
 			status = GIT_DELTA_UNMODIFIED;
 	}
 
@@ -725,14 +731,20 @@ int git_diff__from_iterators(
 						recurse_into_dir = false;
 				}
 
-				if (contains_oitem || recurse_into_dir) {
-					/* if this directory is ignored, remember it as the
-					 * "ignore_prefix" for processing contained items
-					 */
-					if (delta_type == GIT_DELTA_UNTRACKED &&
-						git_iterator_current_is_ignored(new_iter))
-						git_buf_sets(&ignore_prefix, nitem->path);
+				/* if directory is ignored, remember ignore_prefix */
+				if ((contains_oitem || recurse_into_dir) &&
+					delta_type == GIT_DELTA_UNTRACKED &&
+					git_iterator_current_is_ignored(new_iter))
+				{
+					git_buf_sets(&ignore_prefix, nitem->path);
+					delta_type = GIT_DELTA_IGNORED;
 
+					/* skip recursion if we've just learned this is ignored */
+					if (DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS))
+						recurse_into_dir = false;
+				}
+
+				if (contains_oitem || recurse_into_dir) {
 					/* advance into directory */
 					error = git_iterator_advance_into(&nitem, new_iter);
 

tests-clar/diff/diff_helpers.c

@@ -42,6 +42,16 @@ int diff_file_cb(
 	return 0;
 }
 
+int diff_print_file_cb(
+	const git_diff_delta *delta,
+	float progress,
+	void *payload)
+{
+	fprintf(stderr, "%c %s\n",
+		git_diff_status_char(delta->status), delta->old_file.path);
+	return diff_file_cb(delta, progress, payload);
+}
+
 int diff_hunk_cb(
 	const git_diff_delta *delta,
 	const git_diff_range *range,

tests-clar/diff/diff_helpers.h

@@ -30,6 +30,11 @@ extern int diff_file_cb(
 	float progress,
 	void *cb_data);
 
+extern int diff_print_file_cb(
+	const git_diff_delta *delta,
+	float progress,
+	void *cb_data);
+
 extern int diff_hunk_cb(
 	const git_diff_delta *delta,
 	const git_diff_range *range,

tests-clar/diff/workdir.c

@@ -953,16 +953,31 @@ void test_diff_workdir__submodules(void)
 	cl_git_pass(git_diff_foreach(
 		diff, diff_file_cb, diff_hunk_cb, diff_line_cb, &exp));
 
-	/* the following differs from "git diff 873585" by two "untracked" file
-	 * because the diff list includes the "not" and "not-submodule" dirs which
-	 * are not displayed in the text diff.
+	/* so "git diff 873585" returns:
+	 *  M   .gitmodules
+	 *  A   just_a_dir/contents
+	 *  A   just_a_file
+	 *  A   sm_added_and_uncommited
+	 *  A   sm_changed_file
+	 *  A   sm_changed_head
+	 *  A   sm_changed_index
+	 *  A   sm_changed_untracked_file
+	 *  M   sm_missing_commits
+	 *  A   sm_unchanged
+	 * which is a little deceptive because of the difference between the
+	 * "git diff <treeish>" results from "git_diff_tree_to_workdir".  The
+	 * only significant difference is that those Added items will show up
+	 * as Untracked items in the pure libgit2 diff.
+	 *
+	 * Then add in the two extra untracked items "not" and "not-submodule"
+	 * to get the 12 files reported here.
 	 */
 
-	cl_assert_equal_i(11, exp.files);
+	cl_assert_equal_i(12, exp.files);
 
 	cl_assert_equal_i(0, exp.file_status[GIT_DELTA_ADDED]);
 	cl_assert_equal_i(0, exp.file_status[GIT_DELTA_DELETED]);
-	cl_assert_equal_i(1, exp.file_status[GIT_DELTA_MODIFIED]);
+	cl_assert_equal_i(2, exp.file_status[GIT_DELTA_MODIFIED]);
 	cl_assert_equal_i(0, exp.file_status[GIT_DELTA_IGNORED]);
 	cl_assert_equal_i(10, exp.file_status[GIT_DELTA_UNTRACKED]);
 

tests-clar/status/ignore.c

@@ -199,12 +199,15 @@ void test_status_ignore__subdirectories(void)
 	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "ignore_me"));
 	cl_assert(ignored);
 
-	/* So, interestingly, as per the comment in diff_from_iterators() the
-	 * following file is ignored, but in a way so that it does not show up
-	 * in status even if INCLUDE_IGNORED is used.  This actually matches
-	 * core git's behavior - if you follow these steps and try running "git
-	 * status -uall --ignored" then the following file and directory will
-	 * not show up in the output at all.
+	/* I've changed libgit2 so that the behavior here now differs from
+	 * core git but seems to make more sense.  In core git, the following
+	 * items are skipped completed, even if --ignored is passed to status.
+	 * It you mirror these steps and run "git status -uall --ignored" then
+	 * you will not see "test/ignore_me/" in the results.
+	 *
+	 * However, we had a couple reports of this as a bug, plus there is a
+	 * similar circumstance where we were differing for core git when you
+	 * used a rooted path for an ignore, so I changed this behavior.
 	 */
 	cl_git_pass(git_futils_mkdir_r(
 		"empty_standard_repo/test/ignore_me", NULL, 0775));
@@ -215,7 +218,7 @@ void test_status_ignore__subdirectories(void)
 
 	memset(&st, 0, sizeof(st));
 	cl_git_pass(git_status_foreach(g_repo, cb_status__single, &st));
-	cl_assert_equal_i(2, st.count);
+	cl_assert_equal_i(3, st.count);
 
 	cl_git_pass(git_status_file(&st.status, g_repo, "test/ignore_me/file"));
 	cl_assert(st.status == GIT_STATUS_IGNORED);
@@ -230,26 +233,38 @@ void test_status_ignore__subdirectories_recursion(void)
 	/* Let's try again with recursing into ignored dirs turned on */
 	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
 	status_entry_counts counts;
-	static const char *paths[] = {
+	static const char *paths_r[] = {
 		".gitignore",
+		"ignore_also/file",
 		"ignore_me",
 		"test/ignore_me/and_me/file",
 		"test/ignore_me/file",
 		"test/ignore_me/file2",
 	};
-	static const unsigned int statuses[] = {
+	static const unsigned int statuses_r[] = {
 		GIT_STATUS_WT_NEW,
 		GIT_STATUS_IGNORED,
 		GIT_STATUS_IGNORED,
 		GIT_STATUS_IGNORED,
 		GIT_STATUS_IGNORED,
+		GIT_STATUS_IGNORED,
+	};
+	static const char *paths_nr[] = {
+		".gitignore",
+		"ignore_also/",
+		"ignore_me",
+		"test/ignore_me/",
+	};
+	static const unsigned int statuses_nr[] = {
+		GIT_STATUS_WT_NEW,
+		GIT_STATUS_IGNORED,
+		GIT_STATUS_IGNORED,
+		GIT_STATUS_IGNORED,
 	};
-
-	opts.flags = GIT_STATUS_OPT_DEFAULTS | GIT_STATUS_OPT_RECURSE_IGNORED_DIRS;
 
 	g_repo = cl_git_sandbox_init("empty_standard_repo");
 
-	cl_git_rewritefile("empty_standard_repo/.gitignore", "ignore_me\n");
+	cl_git_rewritefile("empty_standard_repo/.gitignore", "ignore_me\n/ignore_also\n");
 
 	cl_git_mkfile(
 		"empty_standard_repo/ignore_me", "I'm going to be ignored!");
@@ -263,11 +278,32 @@ void test_status_ignore__subdirectories_recursion(void)
 		"empty_standard_repo/test/ignore_me/and_me", NULL, 0775));
 	cl_git_mkfile(
 		"empty_standard_repo/test/ignore_me/and_me/file", "Deeply ignored");
+	cl_git_pass(git_futils_mkdir_r(
+		"empty_standard_repo/ignore_also", NULL, 0775));
+	cl_git_mkfile(
+		"empty_standard_repo/ignore_also/file", "I'm going to be ignored!");
+
+	memset(&counts, 0x0, sizeof(status_entry_counts));
+	counts.expected_entry_count = 6;
+	counts.expected_paths = paths_r;
+	counts.expected_statuses = statuses_r;
+
+	opts.flags = GIT_STATUS_OPT_DEFAULTS | GIT_STATUS_OPT_RECURSE_IGNORED_DIRS;
+
+	cl_git_pass(git_status_foreach_ext(
+		g_repo, &opts, cb_status__normal, &counts));
+
+	cl_assert_equal_i(counts.expected_entry_count, counts.entry_count);
+	cl_assert_equal_i(0, counts.wrong_status_flags_count);
+	cl_assert_equal_i(0, counts.wrong_sorted_path);
+
 
 	memset(&counts, 0x0, sizeof(status_entry_counts));
-	counts.expected_entry_count = 5;
-	counts.expected_paths = paths;
-	counts.expected_statuses = statuses;
+	counts.expected_entry_count = 4;
+	counts.expected_paths = paths_nr;
+	counts.expected_statuses = statuses_nr;
+
+	opts.flags = GIT_STATUS_OPT_DEFAULTS;
 
 	cl_git_pass(git_status_foreach_ext(
 		g_repo, &opts, cb_status__normal, &counts));

tests-clar/status/status_helpers.c

@@ -47,3 +47,51 @@ int cb_status__single(const char *p, unsigned int s, void *payload)
 
 	return 0;
 }
+
+int cb_status__print(
+	const char *path, unsigned int status_flags, void *payload)
+{
+	char istatus = ' ', wstatus = ' ';
+	int icount = 0, wcount = 0;
+
+	if (status_flags & GIT_STATUS_INDEX_NEW) {
+		istatus = 'A'; icount++;
+	}
+	if (status_flags & GIT_STATUS_INDEX_MODIFIED) {
+		istatus = 'M'; icount++;
+	}
+	if (status_flags & GIT_STATUS_INDEX_DELETED) {
+		istatus = 'D'; icount++;
+	}
+	if (status_flags & GIT_STATUS_INDEX_RENAMED) {
+		istatus = 'R'; icount++;
+	}
+	if (status_flags & GIT_STATUS_INDEX_TYPECHANGE) {
+		istatus = 'T'; icount++;
+	}
+
+	if (status_flags & GIT_STATUS_WT_NEW) {
+		wstatus = 'A'; wcount++;
+	}
+	if (status_flags & GIT_STATUS_WT_MODIFIED) {
+		wstatus = 'M'; wcount++;
+	}
+	if (status_flags & GIT_STATUS_WT_DELETED) {
+		wstatus = 'D'; wcount++;
+	}
+	if (status_flags & GIT_STATUS_WT_TYPECHANGE) {
+		wstatus = 'T'; wcount++;
+	}
+	if (status_flags & GIT_STATUS_IGNORED) {
+		wstatus = 'I'; wcount++;
+	}
+
+	fprintf(stderr, "%c%c %s (%d/%d%s)\n",
+			istatus, wstatus, path, icount, wcount,
+			(icount > 1 || wcount > 1) ? " INVALID COMBO" : "");
+
+	if (payload)
+		*((int *)payload) += 1;
+
+	return 0;
+}

tests-clar/status/status_helpers.h

@@ -30,4 +30,8 @@ typedef struct {
 
 extern int cb_status__single(const char *p, unsigned int s, void *payload);
 
+/* cb_status__print takes optional payload of "int *" */
+
+extern int cb_status__print(const char *p, unsigned int s, void *payload);
+
 #endif

tests-clar/status/submodules.c

@@ -166,3 +166,54 @@ void test_status_submodules__moved_head(void)
 		git_status_foreach_ext(g_repo, &opts, cb_status__match, &counts));
 	cl_assert_equal_i(6, counts.entry_count);
 }
+
+void test_status_submodules__dirty_workdir_only(void)
+{
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
+	status_entry_counts counts;
+	static const char *expected_files_with_sub[] = {
+		".gitmodules",
+		"added",
+		"deleted",
+		"ignored",
+		"modified",
+		"testrepo",
+		"untracked"
+	};
+	static unsigned int expected_status_with_sub[] = {
+		GIT_STATUS_WT_MODIFIED,
+		GIT_STATUS_INDEX_NEW,
+		GIT_STATUS_INDEX_DELETED,
+		GIT_STATUS_IGNORED,
+		GIT_STATUS_WT_MODIFIED,
+		GIT_STATUS_WT_MODIFIED,
+		GIT_STATUS_WT_NEW
+	};
+
+	cl_git_rewritefile("submodules/testrepo/README", "heyheyhey");
+	cl_git_mkfile("submodules/testrepo/all_new.txt", "never seen before");
+
+	/* first do a normal status, which should now include the submodule */
+
+	memset(&counts, 0, sizeof(counts));
+	counts.expected_paths = expected_files_with_sub;
+	counts.expected_statuses = expected_status_with_sub;
+
+	opts.flags = GIT_STATUS_OPT_DEFAULTS;
+
+	cl_git_pass(
+		git_status_foreach_ext(g_repo, &opts, cb_status__match, &counts));
+	cl_assert_equal_i(7, counts.entry_count);
+
+	/* try again with EXCLUDE_SUBMODULES which should skip it */
+
+	memset(&counts, 0, sizeof(counts));
+	counts.expected_paths = expected_files;
+	counts.expected_statuses = expected_status;
+
+	opts.flags = GIT_STATUS_OPT_DEFAULTS | GIT_STATUS_OPT_EXCLUDE_SUBMODULES;
+
+	cl_git_pass(
+		git_status_foreach_ext(g_repo, &opts, cb_status__match, &counts));
+	cl_assert_equal_i(6, counts.entry_count);
+}