should not use rb_ary_modify()

ractor_copy() used rb_ary_modify() to make sure this array is not
sharing anything, but it also checks frozen flag. So frozen arrays
raises an error. To solve this issue, this patch introduces new
function rb_ary_cancel_sharing() which makes sure the array does not
share another array and it doesn't check frozen flag.
[Bug #17343]

A test is quoted from https://github.com/ruby/ruby/pull/3817

1 files changed, 3 insertions, 2 deletions

diff --git a/ractor.c b/ractor.c
index 4a75b41fc5..693bbe274d 100644
--- a/ractor.c
+++ b/ractor.c
@@ -2314,7 +2314,7 @@ obj_traverse_replace_i(VALUE obj, struct obj_traverse_replace_data *data)
 
       case T_ARRAY:
         {
-            rb_ary_modify(obj);
+            rb_ary_cancel_sharing(obj);
 #if USE_TRANSIENT_HEAP
             if (data->move) rb_ary_transient_heap_evacuate(obj, TRUE);
 #endif
@@ -2537,7 +2537,8 @@ copy_leave(VALUE obj, struct obj_traverse_replace_data *data)
     return traverse_cont;
 }
 
-static VALUE ractor_copy(VALUE obj)
+static VALUE
+ractor_copy(VALUE obj)
 {
     VALUE val = rb_obj_traverse_replace(obj, copy_enter, copy_leave, false);
     if (val != Qundef) {