[Fix rubocop#255] Fix a false positive for `Style/RedundantEqualityCo…

…mparisonBlock`

Fixes rubocop#255.

This PR fixes a false positive for `Style/RedundantEqualityComparisonBlock`
when using block argument is used for an argument of operand.

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### Bug fixes
+
+* [#255](https://github.com/rubocop/rubocop-performance/issues/255): Fix a false positive for `Style/RedundantEqualityComparisonBlock` when using block argument is used for an argument of operand. ([@koic][])
+
 ## 1.11.4 (2021-07-07)
 
 ### Bug fixes

lib/rubocop/cop/performance/redundant_equality_comparison_block.rb

@@ -74,12 +74,27 @@ def same_block_argument_and_is_a_argument?(block_body, block_argument)
 
         def new_argument(block_argument, block_body)
           if block_argument.source == block_body.receiver.source
-            block_body.first_argument.source
+            rhs = block_body.first_argument
+            return if use_block_argument_in_method_argument_of_operand?(block_argument, rhs)
+
+            rhs.source
           elsif block_argument.source == block_body.first_argument.source
-            block_body.receiver.source
+            lhs = block_body.receiver
+            return if use_block_argument_in_method_argument_of_operand?(block_argument, lhs)
+
+            lhs.source
           end
         end
 
+        def use_block_argument_in_method_argument_of_operand?(block_argument, operand)
+          return false unless operand.send_type?
+
+          arguments = operand.arguments
+          arguments.inject(arguments.map(&:source)) do |operand_sources, argument|
+            operand_sources + argument.each_descendant(:lvar).map(&:source)
+          end.any?(block_argument.source)
+        end
+
         def offense_range(node)
           node.send_node.loc.selector.join(node.source_range.end)
         end

spec/rubocop/cop/performance/redundant_equality_comparison_block_spec.rb

@@ -106,4 +106,28 @@
       items.do_something { |item| item == other }
     RUBY
   end
+
+  it 'does not register an offense when using block argument is used for an argument of RHS operand' do
+    expect_no_offenses(<<~RUBY)
+      items.any? { |item| item == do_something(item) }
+    RUBY
+  end
+
+  it 'does not register an offense when using block argument is used for a argument of LHS operand' do
+    expect_no_offenses(<<~RUBY)
+      items.any? { |item| do_something(item) == item }
+    RUBY
+  end
+
+  it 'does not register an offense when using block argument is used for a nested argument of RHS operand' do
+    expect_no_offenses(<<~RUBY)
+      items.any? { |item| item == do_something[0..item] }
+    RUBY
+  end
+
+  it 'does not register an offense when using block argument is used for a nested argument of LHS operand' do
+    expect_no_offenses(<<~RUBY)
+      items.any? { |item| do_something[0..item] == item }
+    RUBY
+  end
 end