Make git_odb_foreach_cb take const param

This makes the first OID param of the ODB callback a const pointer
and also propogates that change all the way to the backends.

2 files changed, 9 insertions, 7 deletions

diff --git a/include/git2/odb.h b/include/git2/odb.h
index d41c2fb52..f2633d11c 100644
--- a/include/git2/odb.h
+++ b/include/git2/odb.h
@@ -23,11 +23,6 @@
 GIT_BEGIN_DECL
 
 /**
- * Function type for callbacks from git_odb_foreach.
- */
-typedef int (*git_odb_foreach_cb)(git_oid *id, void *payload);
-
-/**
  * Create a new object database with no backends.
  *
  * Before the ODB can be used for read/writing, a custom database
diff --git a/include/git2/odb_backend.h b/include/git2/odb_backend.h
index 694803efd..04658f9b3 100644
--- a/include/git2/odb_backend.h
+++ b/include/git2/odb_backend.h
@@ -24,7 +24,14 @@ GIT_BEGIN_DECL
 struct git_odb_stream;
 struct git_odb_writepack;
 
-/** An instance for a custom backend */
+/**
+ * Function type for callbacks from git_odb_foreach.
+ */
+typedef int (*git_odb_foreach_cb)(const git_oid *id, void *payload);
+
+/**
+ * An instance for a custom backend
+ */
 struct git_odb_backend {
 	git_odb *odb;
 
@@ -79,7 +86,7 @@ struct git_odb_backend {
 
 	int (* foreach)(
 			struct git_odb_backend *,
-			int (*cb)(git_oid *oid, void *payload),
+			git_odb_foreach_cb cb,
 			void *payload);
 
 	int (* writepack)(