merge revision(s) ec8e5f5aa64e2a54cf1e303f2b012c98e8d521ba,5a187e26adc8aa32367f294c1496935c7356d386: [Backport #15952]

	array.c: always check frozenness in Array#unshift. Fixes [Bug #15952]

	Closes: https://github.com/ruby/ruby/pull/2251

	array.c add back shared array optimization to
	 ary_ensure_room_for_unshift

	Bug fix in commit ec8e5f5aa64e2a [Bug #15952] disabled an
	optimization in this function.

	Closes: https://github.com/ruby/ruby/pull/2252

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67740 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 0 deletions

diff --git a/array.c b/array.c
index 7b92bfe5b1..ec6f232662 100644
--- a/array.c
+++ b/array.c
@@ -1368,6 +1368,7 @@ ary_ensure_room_for_unshift(VALUE ary, int argc)
 	VALUE shared = ARY_SHARED(ary);
 	capa = RARRAY_LEN(shared);
 	if (ARY_SHARED_OCCUPIED(shared) && capa > new_len) {
+            rb_ary_modify_check(ary);
             head = RARRAY_CONST_PTR_TRANSIENT(ary);
             sharedp = RARRAY_CONST_PTR_TRANSIENT(shared);
 	    goto makeroom_if_need;