just null out cancelled finalizers

src/gc-common.c

@@ -487,22 +487,18 @@ int erase_finalizer_at(arraylist_t *list, jl_value_t *o, size_t idx)
     void **items = list->items;
     void *v = items[idx];
     if (o == (jl_value_t*)gc_ptr_clear_tag(v, 1)) {
-        for (size_t j = idx + 2; j < list->len; j += 2) {
-            items[j-2] = items[j];
-            items[j-1] = items[j+1];
-        }
-        list->len = list->len - 2;
+        items[idx] = NULL;
+        items[idx+1] = NULL;
         return 1;
     }
     return 0;
 }
 
 int erase_finalizer(arraylist_t *list, jl_value_t *o)
 {
-    for (size_t i = 0; i < list->len; i += 2) {
+    for (size_t i = 0; i < list->len; i += 2)
         if (erase_finalizer_at(list, o, i))
             return 1;
-    }
     return 0;
 }
 

test/compiler/inline.jl

@@ -1672,7 +1672,7 @@ const _xs_with_finalizers_ = Any[]
     if _gc_or_register[]
         # this would hit the slow path
         empty!(_xs_with_finalizers_)
-        GC.gc()
+        GC.gc(); GC.gc();
     else
         # still hits the fast path
         push!(_xs_with_finalizers_, finalizer(Ref(y)) do x