Fix Range#overlap? ignoring empty ranges

Previously, #overlap? would incorrectly return true when one of the
ranges is effectively "empty":

```ruby
(2...2).overlap? 1..2 # => true
(1..2).overlap? 2...2 # => true
```

This is fixed in the Ruby 3.3 implementation of Range#overlap?, so this
commit fixes it for Ruby < 3.3 as well.

The tests added are from the Ruby repository and the implementation is
effectively a Ruby version of the fix in C.

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Shouichi Kamiya <shouichi.kamiya@gmail.com>

activesupport/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Fix Range#overlap? not taking empty ranges into account on Ruby < 3.3
+
+    *Nobuyoshi Nakada*, *Shouichi Kamiya*, *Hartley McGuire*
+
 *   Use Ruby 3.3 Range#overlap? if available
 
     *Yasuo Honda*

activesupport/lib/active_support/core_ext/range/overlap.rb

@@ -6,7 +6,33 @@ class Range
   #  (1..5).overlap?(7..9) # => false
   unless Range.method_defined?(:overlap?)
     def overlap?(other)
-      other.begin == self.begin || cover?(other.begin) || other.cover?(self.begin)
+      raise TypeError unless other.is_a? Range
+
+      self_begin = self.begin
+      other_end = other.end
+      other_excl = other.exclude_end?
+
+      return false if _empty_range?(self_begin, other_end, other_excl)
+
+      other_begin = other.begin
+      self_end = self.end
+      self_excl = self.exclude_end?
+
+      return false if _empty_range?(other_begin, self_end, self_excl)
+      return true if self_begin == other_begin
+
+      return false if _empty_range?(self_begin, self_end, self_excl)
+      return false if _empty_range?(other_begin, other_end, other_excl)
+
+      true
+    end
+
+    private
+    def _empty_range?(b, e, excl)
+      return false if b.nil? || e.nil?
+
+      comp = b <=> e
+      comp.nil? || comp > 0 || (comp == 0 && excl)
     end
   end
 

activesupport/test/core_ext/range_ext_test.rb

@@ -70,6 +70,67 @@ def test_overlaps_alias
     assert_not (1...5).overlaps?(6..10)
   end
 
+  def test_overlap_behaves_like_ruby
+    assert_not_operator(0..2, :overlap?, -2..-1)
+    assert_not_operator(0..2, :overlap?, -2...0)
+    assert_operator(0..2, :overlap?, -1..0)
+    assert_operator(0..2, :overlap?, 1..2)
+    assert_operator(0..2, :overlap?, 2..3)
+    assert_not_operator(0..2, :overlap?, 3..4)
+    assert_not_operator(0...2, :overlap?, 2..3)
+    assert_operator(..0, :overlap?, -1..0)
+    assert_operator(...0, :overlap?, -1..0)
+    assert_operator(..0, :overlap?, 0..1)
+    assert_operator(..0, :overlap?, ..1)
+    assert_not_operator(..0, :overlap?, 1..2)
+    assert_not_operator(...0, :overlap?, 0..1)
+    assert_not_operator(0.., :overlap?, -2..-1)
+    assert_not_operator(0.., :overlap?, ...0)
+    assert_operator(0.., :overlap?, -1..0)
+    assert_operator(0.., :overlap?, ..0)
+    assert_operator(0.., :overlap?, 0..1)
+    assert_operator(0.., :overlap?, 1..2)
+    assert_operator(0.., :overlap?, 1..)
+
+    assert_not_operator((1..3), :overlap?, ("a".."d"))
+
+    assert_raise(TypeError) { (0..).overlap?(1) }
+    assert_raise(TypeError) { (0..).overlap?(nil) }
+
+    assert_operator((1..3), :overlap?, (2..4))
+    assert_operator((1...3), :overlap?, (2..3))
+    assert_operator((2..3), :overlap?, (1..2))
+    assert_operator((..3), :overlap?, (3..))
+    assert_operator((nil..nil), :overlap?, (3..))
+    assert_operator((nil...nil), :overlap?, (nil..))
+
+    assert_raise(TypeError) { (1..3).overlap?(1) }
+
+    assert_not_operator((1..2), :overlap?, (2...2))
+    assert_not_operator((2...2), :overlap?, (1..2))
+
+    assert_not_operator((4..1), :overlap?, (2..3))
+    assert_not_operator((4..1), :overlap?, (..3))
+    assert_not_operator((4..1), :overlap?, (2..))
+
+    assert_not_operator((1..4), :overlap?, (3..2))
+    assert_not_operator((..4), :overlap?, (3..2))
+    assert_not_operator((1..), :overlap?, (3..2))
+
+    assert_not_operator((4..5), :overlap?, (2..3))
+    assert_not_operator((4..5), :overlap?, (2...4))
+
+    assert_not_operator((1..2), :overlap?, (3..4))
+    assert_not_operator((1...3), :overlap?, (3..4))
+
+    assert_not_operator((4..5), :overlap?, (2..3))
+    assert_not_operator((4..5), :overlap?, (2...4))
+
+    assert_not_operator((1..2), :overlap?, (3..4))
+    assert_not_operator((1...3), :overlap?, (3..4))
+    assert_not_operator((...3), :overlap?, (3..))
+  end
+
   def test_should_include_identical_inclusive
     assert((1..10).include?(1..10))
   end