Make all non-user-creatable structures non-comparable (#802)

This change makes all non-user-creatable structures non-comparable. This
makes it easier to add changes later that don't introduce breaking
changes from the go compatibility guarantees perspective.

This, of course, implies that this change _is_ a breaking change, but since
these structures are not intended to be created by users (or de-referenced),
it should be okay.

1 files changed, 2 insertions, 0 deletions

diff --git a/branch.go b/branch.go
index 217b877..9596d0b 100644
--- a/branch.go
+++ b/branch.go
@@ -19,6 +19,7 @@ const (
 )
 
 type Branch struct {
+	doNotCompare
 	*Reference
 }
 
@@ -27,6 +28,7 @@ func (r *Reference) Branch() *Branch {
 }
 
 type BranchIterator struct {
+	doNotCompare
 	ptr  *C.git_branch_iterator
 	repo *Repository
 }