[Fix rubocop#3383] Handle properly nested methods in RedundantSelf (r…

…ubocop#3459)

That commit adds failing test for issue rubocop#3383, and
fixes the problem by adding scoped local vars
management.

CHANGELOG.md

@@ -12,6 +12,7 @@
 
 ### Bug fixes
 
+* [#3383](https://github.com/bbatsov/rubocop/issues/3383): Fix the local variable reset issue with `Style/RedundantSelf` cop. ([@bankair][])
 * [#3445](https://github.com/bbatsov/rubocop/issues/3445): Fix bad autocorrect for `Style/AndOr` cop. ([@mikezter][])
 * [#3349](https://github.com/bbatsov/rubocop/issues/3349): Fix bad autocorrect for `Style/Lambda` cop. ([@metcalf][])
 * [#3351](https://github.com/bbatsov/rubocop/issues/3351): Fix bad auto-correct for `Performance/RedundantMatch` cop. ([@annaswims][])

lib/rubocop/cop/style/redundant_self.rb

@@ -49,7 +49,7 @@ class RedundantSelf < Cop
         def initialize(config = nil, options = nil)
           super
           @allowed_send_nodes = []
-          @local_variables = []
+          @local_variables_scopes = Hash.new { |hash, key| hash[key] = [] }
         end
 
         # Assignment of self.x
@@ -68,12 +68,12 @@ def on_op_asgn(node)
 
         # Using self.x to distinguish from local variable x
 
-        def on_def(_node)
-          @local_variables = []
+        def on_def(node)
+          add_scope(node)
         end
 
-        def on_defs(_node)
-          @local_variables = []
+        def on_defs(node)
+          add_scope(node)
         end
 
         def on_args(node)
@@ -86,7 +86,7 @@ def on_blockarg(node)
 
         def on_lvasgn(node)
           lhs, _rhs = *node
-          @local_variables << lhs
+          @local_variables_scopes[node] << lhs
         end
 
         # Detect offenses
@@ -97,8 +97,7 @@ def on_send(node)
           return unless regular_method_call?(node)
 
           return if @allowed_send_nodes.include?(node) ||
-                    @local_variables.include?(method_name)
-
+                    @local_variables_scopes[node].include?(method_name)
           add_offense(node, :expression)
         end
 
@@ -112,6 +111,13 @@ def autocorrect(node)
 
         private
 
+        def add_scope(node)
+          local_variables = []
+          node.descendants.each do |child_node|
+            @local_variables_scopes[child_node] = local_variables
+          end
+        end
+
         def regular_method_call?(node)
           _receiver, method_name, *_args = *node
 
@@ -123,7 +129,7 @@ def regular_method_call?(node)
 
         def on_argument(node)
           name, = *node
-          @local_variables << name
+          @local_variables_scopes[node] << name
         end
 
         def keyword?(method_name)

spec/rubocop/cop/style/redundant_self_spec.rb

@@ -125,6 +125,23 @@
       inspect_source(cop, src)
       expect(cop.offenses).to be_empty
     end
+
+    it 'accepts a self receiver used to distinguish from an argument' do
+      src = ['def foo(bar)',
+             '  puts bar, self.bar',
+             'end']
+      inspect_source(cop, src)
+      expect(cop.offenses).to be_empty
+    end
+
+    it 'accepts a self receiver used to distinguish from an argument' do
+      src = ['def foo(bar)',
+             '  def inner_method(); end',
+             '  puts bar, self.bar',
+             'end']
+      inspect_source(cop, src)
+      expect(cop.offenses).to be_empty
+    end
   end
 
   describe 'class methods' do