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, 3 insertions, 1 deletions

diff --git a/refdb.go b/refdb.go
index 578f43c..a8b1715 100644
--- a/refdb.go
+++ b/refdb.go
@@ -13,11 +13,13 @@ import (
 )
 
 type Refdb struct {
+	doNotCompare
 	ptr *C.git_refdb
 	r   *Repository
 }
 
 type RefdbBackend struct {
+	doNotCompare
 	ptr *C.git_refdb_backend
 }
 
@@ -38,7 +40,7 @@ func (v *Repository) NewRefdb() (refdb *Refdb, err error) {
 }
 
 func NewRefdbBackendFromC(ptr unsafe.Pointer) (backend *RefdbBackend) {
-	backend = &RefdbBackend{(*C.git_refdb_backend)(ptr)}
+	backend = &RefdbBackend{ptr: (*C.git_refdb_backend)(ptr)}
 	return backend
 }