[Fix rubocop#1123] Setter calls in safe assignment

Support if (a.b = x).

CHANGELOG.md

@@ -19,6 +19,7 @@
 * [#1111](https://github.com/bbatsov/rubocop/issues/1111): Fix problem in `EndOfLine` with reading non-UTF-8 encoded files. ([@jonas054][])
 * [#1115](https://github.com/bbatsov/rubocop/issues/1115): Fix `Next` to ignore super nodes. ([@geniou][])
 * [#1117](https://github.com/bbatsov/rubocop/issues/1117): Don't auto-correct indentation in scopes that contain block comments (`=begin`..`=end`). ([@jonas054][])
+* [#1123](https://github.com/bbatsov/rubocop/pull/1123): Support setter calls in safe assignment in `ParenthesesAroundCondition`. ([@jonas054][])
 
 ## 0.22.0 (20/04/2014)
 

lib/rubocop/cop/mixin/safe_assignment.rb

@@ -7,8 +7,19 @@ module Cop
     # assignment as a condition. It's not a mistake."
     module SafeAssignment
       def safe_assignment?(node)
-        node.type == :begin && node.children.size == 1 &&
-          Util::EQUALS_ASGN_NODES.include?(node.children[0].type)
+        return false unless node.type == :begin
+        return false unless node.children.size == 1
+
+        child = node.children.first
+        case child.type
+        when *Util::EQUALS_ASGN_NODES
+          true
+        when :send
+          _receiver, method_name, _args = *child
+          method_name.to_s.end_with?('=')
+        else
+          false
+        end
       end
 
       def safe_assignment_allowed?