[Bug #20324] Uncomparable ranges are not overlapping

2 files changed, 12 insertions, 2 deletions

diff --git a/range.c b/range.c
index 22dbd989d4..e9073e53c4 100644
--- a/range.c
+++ b/range.c
@@ -2373,8 +2373,16 @@ range_overlap(VALUE range, VALUE other)
     if (empty_region_p(self_beg, other_end, other_excl)) return Qfalse;
     if (empty_region_p(other_beg, self_end, self_excl)) return Qfalse;
 
-    /* if both begin values are equal, no more comparisons needed */
-    if (rb_equal(self_beg, other_beg)) return Qtrue;
+    if (!NIL_P(self_beg) && !NIL_P(other_beg)) {
+        VALUE cmp = rb_funcall(self_beg, id_cmp, 1, other_beg);
+        if (NIL_P(cmp)) return Qfalse;
+        /* if both begin values are equal, no more comparisons needed */
+        if (rb_cmpint(cmp, self_beg, other_beg) == 0) return Qtrue;
+    }
+    else if (NIL_P(self_beg) && NIL_P(other_beg)) {
+        VALUE cmp = rb_funcall(self_end, id_cmp, 1, other_end);
+        return RBOOL(!NIL_P(cmp));
+    }
 
     if (empty_region_p(self_beg, self_end, self_excl)) return Qfalse;
     if (empty_region_p(other_beg, other_end, other_excl)) return Qfalse;
diff --git a/test/ruby/test_range.rb b/test/ruby/test_range.rb
index fe14bb9b3b..2aa69dc6a4 100644
--- a/test/ruby/test_range.rb
+++ b/test/ruby/test_range.rb
@@ -1265,6 +1265,8 @@ class TestRange < Test::Unit::TestCase
     assert_operator(0.., :overlap?, 1..)
 
     assert_not_operator((1..3), :overlap?, ('a'..'d'))
+    assert_not_operator((1..), :overlap?, ('a'..))
+    assert_not_operator((..1), :overlap?, (..'a'))
 
     assert_raise(TypeError) { (0..).overlap?(1) }
     assert_raise(TypeError) { (0..).overlap?(nil) }