Ensure shape_id is never used on T_IMEMO

It doesn't make sense to set ivars or anything shape
related on a T_IMEMO.

Co-Authored-By: John Hawthorn <john@hawthorn.email>

1 files changed, 5 insertions, 1 deletions

diff --git a/eval.c b/eval.c
index f845bf98ae..739babf93d 100644
--- a/eval.c
+++ b/eval.c
@@ -529,10 +529,14 @@ exc_setup_message(const rb_execution_context_t *ec, VALUE mesg, VALUE *cause)
         rb_exc_check_circular_cause(*cause);
 #else
         VALUE c = *cause;
-        while (!NIL_P(c = rb_attr_get(c, id_cause))) {
+        while (!NIL_P(c)) {
             if (c == mesg) {
                 rb_raise(rb_eArgError, "circular causes");
             }
+            if (THROW_DATA_P(c)) {
+                break;
+            }
+            c = rb_attr_get(c, id_cause);
         }
 #endif
     }