ffi: bugfix: clone of type points to old self.

* ffi.c (ffi_type_copy, ffi_type_copy_new_ops): The cloned txr_ffi_type
structure must have a self member which points to the new cobj,
not the original one. Otherwise things are inconsistent. For instance
if the clone is being made for the purposes of adjusting alignment,
any operation which chases the self pointer will be accessing incorrect
attributes. One example of this is (alignof foo.bar) where if bar
is the clone of a type, this will incorrectly report the alignment of
the original from which bar was cloned, and the original alignment,
not the adjusted alignment is reported.

1 files changed, 6 insertions, 2 deletions

diff --git a/ffi.c b/ffi.c
index 4fbb6d28..437713d7 100644
--- a/ffi.c
+++ b/ffi.c
@@ -3217,14 +3217,18 @@ static val ffi_type_copy(val orig)
 {
   struct txr_ffi_type *otft = ffi_type_struct(orig);
   struct txr_ffi_type *ctft = otft->clone(otft);
-  return cobj(coerce(mem_t *, ctft), orig->co.cls, orig->co.ops);
+  val obj = cobj(coerce(mem_t *, ctft), orig->co.cls, orig->co.ops);
+  ctft->self = obj;
+  return obj;
 }
 
 static val ffi_type_copy_new_ops(val orig, struct cobj_ops *ops)
 {
   struct txr_ffi_type *otft = ffi_type_struct(orig);
   struct txr_ffi_type *ctft = otft->clone(otft);
-  return cobj(coerce(mem_t *, ctft), orig->co.cls, ops);
+  val obj = cobj(coerce(mem_t *, ctft), orig->co.cls, ops);
+  ctft->self = obj;
+  return obj;
 }
 
 static struct txr_ffi_type *ffi_simple_clone(struct txr_ffi_type *orig)