Add ignore_submodules to diff options

This adds correct support for an equivalent to --ignore-submodules
in diff, where an actual ignore value can be passed to diff to
override the per submodule settings in the configuration.

This required tweaking the constants for ignore values so that
zero would not be used and could represent an unset option to the
diff.  This was an opportunity to move the submodule values into
include/git2/types.h and to rename the poorly named DEFAULT values
for ignore and update constants to RESET instead.

Now the GIT_DIFF_IGNORE_SUBMODULES flag is exactly the same as
setting the ignore_submodules option to GIT_SUBMODULE_IGNORE_ALL
(which is actually a minor change from the old behavior in that
submodules will now be treated as UNMODIFIED deltas instead of
being left out totally - if you set GIT_DIFF_INCLUDE_UNMODIFIED).

This includes tests for the various new settings.

1 files changed, 34 insertions, 0 deletions

diff --git a/include/git2/types.h b/include/git2/types.h
index dc344075c..1da0d3ed2 100644
--- a/include/git2/types.h
+++ b/include/git2/types.h
@@ -229,6 +229,40 @@ typedef struct git_transfer_progress {
  */
 typedef int (*git_transfer_progress_callback)(const git_transfer_progress *stats, void *payload);
 
+/**
+ * Opaque structure representing a submodule.
+ */
+typedef struct git_submodule git_submodule;
+
+/**
+ * Values that could be specified for the update rule of a submodule.
+ *
+ * Use the RESET value if you have altered the in-memory update value via
+ * `git_submodule_set_update()` and wish to reset to the original default.
+ */
+typedef enum {
+	GIT_SUBMODULE_UPDATE_RESET = -1,
+	GIT_SUBMODULE_UPDATE_CHECKOUT = 1,
+	GIT_SUBMODULE_UPDATE_REBASE = 2,
+	GIT_SUBMODULE_UPDATE_MERGE = 3,
+	GIT_SUBMODULE_UPDATE_NONE = 4
+} git_submodule_update_t;
+
+/**
+ * Values that could be specified for how closely to examine the
+ * working directory when getting submodule status.
+ *
+ * Use the RESET value if you have altered the in-memory ignore value via
+ * `git_submodule_set_ignore()` and wish to reset to the original value.
+ */
+typedef enum {
+	GIT_SUBMODULE_IGNORE_RESET = -1,    /* reset to on-disk value */
+	GIT_SUBMODULE_IGNORE_NONE = 1,      /* any change or untracked == dirty */
+	GIT_SUBMODULE_IGNORE_UNTRACKED = 2, /* dirty if tracked files change */
+	GIT_SUBMODULE_IGNORE_DIRTY = 3,     /* only dirty if HEAD moved */
+	GIT_SUBMODULE_IGNORE_ALL = 4        /* never dirty */
+} git_submodule_ignore_t;
+
 /** @} */
 GIT_END_DECL