From e23514fed81179d2a837925815954dfd819a5135 Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Mon, 15 Jul 2019 14:03:28 -0700
Subject: [PATCH] Make Array#uniq return subclass instance if called on
 subclass instance

Previously, Array#uniq would return subclass instance if the
length of the array were 2 or greater, and would return Array
instance if the length of the array were 0 or 1.

Fixes [Bug #7768]
---
 array.c                 | 12 ++++++++----
 test/ruby/test_array.rb | 25 +++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/array.c b/array.c
index c693b00755..2165dcfd8e 100644
--- a/array.c
+++ b/array.c
@@ -4961,9 +4961,11 @@ rb_ary_uniq(VALUE ary)
 {
     VALUE hash, uniq;
 
-    if (RARRAY_LEN(ary) <= 1)
-        return rb_ary_dup(ary);
-    if (rb_block_given_p()) {
+    if (RARRAY_LEN(ary) <= 1) {
+        hash = 0;
+        uniq = rb_ary_dup(ary);
+    }
+    else if (rb_block_given_p()) {
 	hash = ary_make_hash_by(ary);
 	uniq = rb_hash_values(hash);
     }
@@ -4972,7 +4974,9 @@ rb_ary_uniq(VALUE ary)
 	uniq = rb_hash_values(hash);
     }
     RBASIC_SET_CLASS(uniq, rb_obj_class(ary));
-    ary_recycle_hash(hash);
+    if (hash) {
+        ary_recycle_hash(hash);
+    }
 
     return uniq;
 }
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index c6aff553ff..475354b548 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1859,6 +1859,31 @@ def test_uniq
     ary = [bug9340, bug9340.dup, bug9340.dup]
     assert_equal 1, ary.uniq.size
     assert_same bug9340, ary.uniq[0]
+
+    sc = Class.new(@cls)
+    a = sc[]
+    b = a.dup
+    assert_instance_of(sc, a.uniq)
+    assert_equal(sc[], a.uniq)
+    assert_equal(b, a)
+
+    a = sc[1]
+    b = a.dup
+    assert_instance_of(sc, a.uniq)
+    assert_equal(sc[1], a.uniq)
+    assert_equal(b, a)
+
+    a = sc[1, 1]
+    b = a.dup
+    assert_instance_of(sc, a.uniq)
+    assert_equal(sc[1], a.uniq)
+    assert_equal(b, a)
+
+    a = sc[1, 1]
+    b = a.dup
+    assert_instance_of(sc, a.uniq{|x| x})
+    assert_equal(sc[1], a.uniq{|x| x})
+    assert_equal(b, a)
   end
 
   def test_uniq_with_block
-- 
2.21.0