Add new InternalAffairs/RedundantSourceRange cop

This PR adds new `InternalAffairs/RedundantSourceRange` cop

It checks for redundant `source_range`.

```ruby
# bad
node.source_range.source

# good
node.source
```

This PR also adds `RuboCop::Ext::Comment#source` so that `Parser::Source::Comment`
can be treated like `Node#source`.

lib/rubocop/cop/bundler/gem_comment.rb

@@ -124,7 +124,7 @@ def preceding_lines(node)
         end
 
         def preceding_comment?(node1, node2)
-          node1 && node2 && precede?(node2, node1) && comment_line?(node2.source_range.source)
+          node1 && node2 && precede?(node2, node1) && comment_line?(node2.source)
         end
 
         def ignored_gem?(node)

lib/rubocop/cop/correctors/line_break_corrector.rb

@@ -35,7 +35,7 @@ def break_line_before(range:, node:, corrector:, configured_width:,
         def move_comment(eol_comment:, node:, corrector:)
           return unless eol_comment
 
-          text = eol_comment.source_range.source
+          text = eol_comment.source
           corrector.insert_before(node, "#{text}\n#{' ' * node.loc.keyword.column}")
           corrector.remove(eol_comment)
         end

lib/rubocop/cop/internal_affairs.rb

@@ -23,6 +23,7 @@
 require_relative 'internal_affairs/redundant_location_argument'
 require_relative 'internal_affairs/redundant_message_argument'
 require_relative 'internal_affairs/redundant_method_dispatch_node'
+require_relative 'internal_affairs/redundant_source_range'
 require_relative 'internal_affairs/single_line_comparison'
 require_relative 'internal_affairs/style_detected_api_use'
 require_relative 'internal_affairs/undefined_config'

lib/rubocop/cop/internal_affairs/cop_description.rb

@@ -77,7 +77,7 @@ def suggestion_for_message(suggestion, match_data)
         end
 
         def first_comment_line(node)
-          node.source_range.source.lines.find { |line| comment_line?(line) }
+          node.source.lines.find { |line| comment_line?(line) }
         end
 
         def comment_body(comment_line)
@@ -86,7 +86,7 @@ def comment_body(comment_line)
 
         def comment_index(node, comment_line)
           body = comment_body(comment_line)
-          node.source_range.source.index(body)
+          node.source.index(body)
         end
 
         def relevant_file?(file)

lib/rubocop/cop/internal_affairs/redundant_source_range.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module InternalAffairs
+      # Checks for redundant `source_range`.
+      #
+      # @example
+      #
+      #   # bad
+      #   node.source_range.source
+      #
+      #   # good
+      #   node.source
+      #
+      class RedundantSourceRange < Base
+        extend AutoCorrector
+
+        MSG = 'Remove the redundant `source_range`.'
+        RESTRICT_ON_SEND = %i[source].freeze
+
+        # @!method redundant_source_range(node)
+        def_node_matcher :redundant_source_range, <<~PATTERN
+          (send $(send _ :source_range) :source)
+        PATTERN
+
+        def on_send(node)
+          return unless (source_range = redundant_source_range(node))
+
+          selector = source_range.loc.selector
+
+          add_offense(selector) do |corrector|
+            corrector.remove(source_range.loc.dot.join(selector))
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/layout/heredoc_indentation.rb

@@ -115,7 +115,7 @@ def adjust_squiggly(corrector, node)
         end
 
         def adjust_minus(corrector, node)
-          heredoc_beginning = node.source_range.source
+          heredoc_beginning = node.source
           corrected = heredoc_beginning.sub(/<<-?/, '<<~')
           corrector.replace(node, corrected)
         end

lib/rubocop/cop/layout/trailing_whitespace.rb

@@ -93,7 +93,7 @@ def whitespace_only?(range)
         end
 
         def static?(heredoc)
-          heredoc.source_range.source.end_with? "'"
+          heredoc.source.end_with? "'"
         end
 
         def skip_heredoc?

lib/rubocop/cop/lint/empty_block.rb

@@ -77,7 +77,7 @@ def allow_comment?(node)
           return false unless processed_source.contains_comment?(node.source_range)
 
           line_comment = processed_source.comment_at_line(node.source_range.line)
-          !line_comment || !comment_disables_cop?(line_comment.source_range.source)
+          !line_comment || !comment_disables_cop?(line_comment.source)
         end
 
         def allow_empty_lambdas?

lib/rubocop/cop/lint/redundant_cop_enable_directive.rb

@@ -82,7 +82,7 @@ def cop_name_indention(comment, name)
         end
 
         def range_with_comma(comment, name)
-          source = comment.source_range.source
+          source = comment.source
 
           begin_pos = cop_name_indention(comment, name)
           end_pos = begin_pos + name.size
@@ -94,7 +94,7 @@ def range_with_comma(comment, name)
 
         def range_to_remove(begin_pos, end_pos, comment)
           start = comment_start(comment)
-          source = comment.source_range.source
+          source = comment.source
 
           if source[begin_pos - 1] == ','
             range_with_comma_before(start, begin_pos, end_pos)
@@ -112,7 +112,7 @@ def range_with_comma_before(start, begin_pos, end_pos)
         # If the list of cops is comma-separated, but without a empty space after the comma,
         # we should **not** remove the prepending empty space, thus begin_pos += 1
         def range_with_comma_after(comment, start, begin_pos, end_pos)
-          begin_pos += 1 if comment.source_range.source[end_pos + 1] != ' '
+          begin_pos += 1 if comment.source[end_pos + 1] != ' '
 
           range_between(start + begin_pos, start + end_pos + 1)
         end

lib/rubocop/cop/mixin/documentation_comment.rb

@@ -23,7 +23,7 @@ def documentation_comment?(node)
       # The args node1 & node2 may represent a RuboCop::AST::Node
       # or a Parser::Source::Comment. Both respond to #loc.
       def preceding_comment?(node1, node2)
-        node1 && node2 && precede?(node2, node1) && comment_line?(node2.source_range.source)
+        node1 && node2 && precede?(node2, node1) && comment_line?(node2.source)
       end
 
       # The args node1 & node2 may represent a RuboCop::AST::Node

lib/rubocop/cop/mixin/hash_transform_method.rb

@@ -179,7 +179,7 @@ def set_new_arg_name(transformed_argname, corrector)
         end
 
         def set_new_body_expression(transforming_body_expr, corrector)
-          body_source = transforming_body_expr.source_range.source
+          body_source = transforming_body_expr.source
           if transforming_body_expr.hash_type? && !transforming_body_expr.braces?
             body_source = "{ #{body_source} }"
           end

lib/rubocop/cop/mixin/statement_modifier.rb

@@ -72,7 +72,7 @@ def first_line_comment(node)
         comment = processed_source.find_comment { |c| same_line?(c, node) }
         return unless comment
 
-        comment_source = comment.source_range.source
+        comment_source = comment.source
         comment_source unless comment_disables_cop?(comment_source)
       end
 

lib/rubocop/cop/style/multiline_ternary_operator.rb

@@ -83,7 +83,7 @@ def replacement(node)
 
         def comments_in_condition(node)
           comments_in_range(node).map do |comment|
-            "#{comment.source_range.source}\n"
+            "#{comment.source}\n"
           end.join
         end
 

lib/rubocop/cop/style/redundant_interpolation.rb

@@ -97,7 +97,7 @@ def embedded_in_percent_array?(node)
         end
 
         def autocorrect_variable_interpolation(corrector, embedded_node, node)
-          replacement = "#{embedded_node.source_range.source}.to_s"
+          replacement = "#{embedded_node.source}.to_s"
 
           corrector.replace(node, replacement)
         end

lib/rubocop/cop/style/redundant_string_escape.rb

@@ -139,7 +139,7 @@ def percent_array_literal?(node)
 
         def heredoc_with_disabled_interpolation?(node)
           if heredoc?(node)
-            node.source_range.source.end_with?("'")
+            node.source.end_with?("'")
           elsif node.parent&.dstr_type?
             heredoc_with_disabled_interpolation?(node.parent)
           else

lib/rubocop/ext/comment.rb

@@ -4,6 +4,10 @@ module RuboCop
   module Ext
     # Extensions to `Parser::Source::Comment`.
     module Comment
+      def source
+        loc.expression.source
+      end
+
       def source_range
         loc.expression
       end

spec/rubocop/cop/internal_affairs/redundant_source_range_spec.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::InternalAffairs::RedundantSourceRange, :config do
+  it 'registers an offense when using `node.source_range.source`' do
+    expect_offense(<<~RUBY)
+      node.source_range.source
+           ^^^^^^^^^^^^ Remove the redundant `source_range`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      node.source
+    RUBY
+  end
+
+  it 'does not register an offense when using `node.source`' do
+    expect_no_offenses(<<~RUBY)
+      node.source
+    RUBY
+  end
+end