commit fe31efbe5c4af576c4c6b77084fc269da2cf509f
Author: Justin Bull <me@justinbull.ca>
Date:   Wed May 6 10:28:05 2020 -0400

    Add Enumerable#empty?

diff --git a/enum.c b/enum.c
index 867eec8f81..f86c8285f5 100644
--- a/enum.c
+++ b/enum.c
@@ -1067,6 +1067,26 @@ enum_first(int argc, VALUE *argv, VALUE obj)
     }
 }
 
+/*
+ *  call-seq:
+ *     enum.empty? -> true or false
+ *
+ *  Returns true if enumerable is empty?
+ *
+ *    [].to_enum.empty?        #=> true
+ *    [nil].to_enum.empty?     #=> false
+ *    [false].to_enum.empty?   #=> false
+ *    [1, 2, 3].to_enum.empty? #=> false
+ *
+ */
+
+
+static VALUE
+enum_empty(VALUE obj)
+{
+    long len = RARRAY_LEN(enum_to_a(0, 0, enum_take(obj, INT2FIX(1))));
+    return len == 0 ? Qtrue : Qfalse;
+}
 
 /*
  *  call-seq:
@@ -4181,6 +4201,7 @@ Init_Enumerable(void)
     rb_define_method(rb_mEnumerable, "group_by", enum_group_by, 0);
     rb_define_method(rb_mEnumerable, "tally", enum_tally, 0);
     rb_define_method(rb_mEnumerable, "first", enum_first, -1);
+    rb_define_method(rb_mEnumerable, "empty?", enum_empty, 0);
     rb_define_method(rb_mEnumerable, "all?", enum_all, -1);
     rb_define_method(rb_mEnumerable, "any?", enum_any, -1);
     rb_define_method(rb_mEnumerable, "one?", enum_one, -1);
diff --git a/test/ruby/test_enum.rb b/test/ruby/test_enum.rb
index 7b647231c8..88fed491eb 100644
--- a/test/ruby/test_enum.rb
+++ b/test/ruby/test_enum.rb
@@ -375,6 +375,16 @@ def test_any
     assert_equal(true, {a: 1, b: 2}.any?(->(kv) { kv == [:b, 2] }))
   end
 
+  def test_empty
+    assert_equal(true, [].to_enum.empty?)
+    assert_equal(true, @empty.empty?)
+    assert_equal(false, @obj.empty?)
+    assert_equal(false, [nil].to_enum.empty?)
+    assert_equal(false, [0].to_enum.empty?)
+    assert_equal(false, [false].to_enum.empty?)
+    assert_equal(false, (1..Float::INFINITY).lazy.empty?)
+  end
+
   def test_any_with_unused_block
     assert_in_out_err [], <<-EOS, [], ["-:1: warning: given block not used"]
       [1, 23].any?(1) {|x| x == 1 }