diff: better document GIT_DIFF_PATHSPEC_DISABLE

Document that `GIT_DIFF_PATHSPEC_DISABLE` is not necessarily about
explicit path matching, but also includes matching of directory
names.  Enforce this in a test.

include/git2/diff.h

@@ -130,7 +130,9 @@ typedef enum {
 	GIT_DIFF_INCLUDE_CASECHANGE = (1u << 11),
 
 	/** If the pathspec is set in the diff options, this flags means to
-	 *  apply it as an exact match instead of as an fnmatch pattern.
+	 *  use exact prefix matches instead of an fnmatch pattern.  Each
+	 *  path in the list must either be a full filename or a subdirectory
+	 *  prefix.
 	 */
 	GIT_DIFF_DISABLE_PATHSPEC_MATCH = (1u << 12),
 

tests/diff/workdir.c

@@ -444,6 +444,216 @@ void test_diff_workdir__to_index_with_pathspec(void)
 	git_diff_free(diff);
 }
 
+void test_diff_workdir__to_index_with_pathlist_disabling_fnmatch(void)
+{
+	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
+	git_diff *diff = NULL;
+	diff_expects exp;
+	char *pathspec = NULL;
+	int use_iterator;
+
+	g_repo = cl_git_sandbox_init("status");
+
+	opts.context_lines = 3;
+	opts.interhunk_lines = 1;
+	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED |
+		GIT_DIFF_DISABLE_PATHSPEC_MATCH;
+	opts.pathspec.strings = &pathspec;
+	opts.pathspec.count   = 0;
+
+	/* ensure that an empty pathspec list is ignored */
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(13, exp.files);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_ADDED]);
+		cl_assert_equal_i(4, exp.file_status[GIT_DELTA_DELETED]);
+		cl_assert_equal_i(4, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(4, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	/* ensure that a single NULL pathspec is filtered out (like when using
+	 * fnmatch filtering)
+	 */
+	opts.pathspec.strings = &pathspec;
+	opts.pathspec.count   = 1;
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(13, exp.files);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_ADDED]);
+		cl_assert_equal_i(4, exp.file_status[GIT_DELTA_DELETED]);
+		cl_assert_equal_i(4, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(4, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	pathspec = "modified_file";
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(1, 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(0, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	/* ensure that subdirs can be specified */
+	pathspec = "subdir";
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(3, exp.files);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_ADDED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_DELETED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	/* ensure that subdirs can be specified with a trailing slash */
+	pathspec = "subdir/";
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(3, exp.files);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_ADDED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_DELETED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(1, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	/* ensure that fnmatching is completely disabled */
+	pathspec = "subdir/*";
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(0, 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(0, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	/* ensure that the prefix matching isn't completely braindead */
+	pathspec = "subdi";
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(0, 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(0, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+
+	/* ensure that fnmatching isn't working at all */
+	pathspec = "*_deleted";
+
+	cl_git_pass(git_diff_index_to_workdir(&diff, g_repo, NULL, &opts));
+
+	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
+		memset(&exp, 0, sizeof(exp));
+
+		if (use_iterator)
+			cl_git_pass(diff_foreach_via_iterator(
+				diff, diff_file_cb, NULL, NULL, NULL, &exp));
+		else
+			cl_git_pass(git_diff_foreach(diff, diff_file_cb, NULL, NULL, NULL, &exp));
+
+		cl_assert_equal_i(0, 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(0, exp.file_status[GIT_DELTA_MODIFIED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_IGNORED]);
+		cl_assert_equal_i(0, exp.file_status[GIT_DELTA_UNTRACKED]);
+	}
+
+	git_diff_free(diff);
+}
+
 void test_diff_workdir__filemode_changes(void)
 {
 	git_diff *diff = NULL;