From f877e02d861cb12d9d57d0c9bc49ac85b9cd616b Mon Sep 17 00:00:00 2001
From: Andrew Szczepanski <aszczepanski@financeit.io>
Date: Mon, 31 Aug 2020 14:01:28 -0400
Subject: [PATCH] Fix `Style/CaseLikeIf` not properly handling overriden
 equality methods

If a class overrides one of `#==`, `#eql?`, or `equal?` and the
overridden method has no arguments, then
CaseLikeIf#find_target_in_equality_node would error as it assumes there
is at least one argument.
---
 CHANGELOG.md                                | 2 ++
 lib/rubocop/cop/style/case_like_if.rb       | 2 +-
 spec/rubocop/cop/style/case_like_if_spec.rb | 8 ++++++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a4aab64bd0d..f0bd4ea9368 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@
 * [#8321](https://github.com/rubocop-hq/rubocop/issues/8321): Enable auto-correction for `Layout/{Def}EndAlignment`, `Lint/EmptyEnsure`. ([@marcandre][])
 * [#8583](https://github.com/rubocop-hq/rubocop/issues/8583): Fix `Style/RedundantRegexpEscape` false positive for line continuations. ([@owst][])
 * [#8593](https://github.com/rubocop-hq/rubocop/issues/8593): Fix `Style/RedundantRegexpCharacterClass` false positive for interpolated multi-line expressions. ([@owst][])
+* [#8624](https://github.com/rubocop-hq/rubocop/pull/8624): Fix an error with the `Style/CaseLikeIf` cop where it does not properly handle overridden equality methods with no arguments. ([@Skipants][])
 
 ### Changes
 
@@ -4821,3 +4822,4 @@
 [@chocolateboy]: https://github.com/chocolateboy
 [@Lykos]: https://github.com/Lykos
 [@jaimerave]: https://github.com/jaimerave
+[@Skipants]: https://github.com/Skipants
diff --git a/lib/rubocop/cop/style/case_like_if.rb b/lib/rubocop/cop/style/case_like_if.rb
index 16570cce578..d454c62fe10 100644
--- a/lib/rubocop/cop/style/case_like_if.rb
+++ b/lib/rubocop/cop/style/case_like_if.rb
@@ -116,7 +116,7 @@ def find_target_in_send_node(node)
         def find_target_in_equality_node(node)
           argument = node.arguments.first
           receiver = node.receiver
-          return unless receiver
+          return unless argument && receiver
 
           if argument.literal? || const_reference?(argument)
             receiver
diff --git a/spec/rubocop/cop/style/case_like_if_spec.rb b/spec/rubocop/cop/style/case_like_if_spec.rb
index 05025c8d467..00c2a23e0ee 100644
--- a/spec/rubocop/cop/style/case_like_if_spec.rb
+++ b/spec/rubocop/cop/style/case_like_if_spec.rb
@@ -336,4 +336,12 @@
       foo if x == 1
     RUBY
   end
+
+  it 'does not register an offense when an object overrides `equal?` with no arity' do
+    expect_no_offenses(<<~RUBY)
+      if x.equal?
+      elsif y
+      end
+    RUBY
+  end
 end