[Fix rubocop#9793] Add Style/QuotedSymbols to enforce consistency i…

…n quoted symbols.

Like `Style/StringLiterals`, this cop checks for the quoting style for symbols to be consistent. Checking whether a symbol _should_ be quoted or not is still handled by `Lint/SymbolConversion`.

This cop shares as much as possible with `Style/StringLiterals` for ease of maintainabilty. As well, for simple configuration, the default "style" is `same_as_string_literals` which will automatically apply the same configuration set up for `Style/StringLiterals` to this cop as well (it defaults to `single_quotes` if `StringLiterals` is not enabled).

changelog/new_add_stylequotedsymbols_to_enforce.md

@@ -0,0 +1 @@
+* [#9793](https://github.com/rubocop/rubocop/issues/9793): Add `Style/QuotedSymbols` to enforce consistency in quoted symbols. ([@dvandersluis][])

config/default.yml

@@ -4186,6 +4186,16 @@ Style/Proc:
   VersionAdded: '0.9'
   VersionChanged: '0.18'
 
+Style/QuotedSymbols:
+  Description: 'Use a consistent style for quoted symbols.'
+  Enabled: pending
+  VersionAdded: '<<next>>'
+  EnforcedStyle: same_as_string_literals
+  SupportedStyles:
+    - same_as_string_literals
+    - single_quotes
+    - double_quotes
+
 Style/RaiseArgs:
   Description: 'Checks the arguments passed to raise/fail.'
   StyleGuide: '#exception-class-messages'

lib/rubocop.rb

@@ -119,6 +119,7 @@
 require_relative 'rubocop/cop/mixin/statement_modifier'
 require_relative 'rubocop/cop/mixin/string_help'
 require_relative 'rubocop/cop/mixin/string_literals_help'
+require_relative 'rubocop/cop/mixin/symbol_help'
 require_relative 'rubocop/cop/mixin/target_ruby_version'
 require_relative 'rubocop/cop/mixin/trailing_body'
 require_relative 'rubocop/cop/mixin/trailing_comma'
@@ -550,6 +551,7 @@
 require_relative 'rubocop/cop/style/perl_backrefs'
 require_relative 'rubocop/cop/style/preferred_hash_methods'
 require_relative 'rubocop/cop/style/proc'
+require_relative 'rubocop/cop/style/quoted_symbols'
 require_relative 'rubocop/cop/style/raise_args'
 require_relative 'rubocop/cop/style/random_with_offset'
 require_relative 'rubocop/cop/style/redundant_argument'

lib/rubocop/cop/lint/symbol_conversion.rb

@@ -66,6 +66,7 @@ module Lint
       class SymbolConversion < Base
         extend AutoCorrector
         include ConfigurableEnforcedStyle
+        include SymbolHelp
 
         MSG = 'Unnecessary symbol conversion; use `%<correction>s` instead.'
         MSG_CONSISTENCY = 'Symbol hash key should be quoted for consistency; ' \
@@ -138,10 +139,6 @@ def in_percent_literal_array?(node)
           node.parent&.array_type? && node.parent&.percent_literal?
         end
 
-        def hash_key?(node)
-          node.parent&.pair_type? && node == node.parent.child_nodes.first
-        end
-
         def correct_hash_key(node)
           # Although some operators can be converted to symbols normally
           # (ie. `:==`), these are not accepted as hash keys and will

lib/rubocop/cop/mixin/string_literals_help.rb

@@ -4,12 +4,10 @@ module RuboCop
   module Cop
     # Common functionality for cops checking single/double quotes.
     module StringLiteralsHelp
-      include StringHelp
-
       private
 
-      def wrong_quotes?(node)
-        src = node.source
+      def wrong_quotes?(src_or_node)
+        src = src_or_node.is_a?(RuboCop::AST::Node) ? src_or_node.source : src_or_node
         return false if src.start_with?('%', '?')
 
         if style == :single_quotes

lib/rubocop/cop/mixin/symbol_help.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    # Classes that include this module just implement functions for working
+    # with symbol nodes.
+    module SymbolHelp
+      def hash_key?(node)
+        node.parent&.pair_type? && node == node.parent.child_nodes.first
+      end
+    end
+  end
+end

lib/rubocop/cop/style/quoted_symbols.rb

@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Style
+      # Checks if the quotes used for quoted symbols match the configured defaults.
+      # By default uses the same configuration as `Style/StringLiterals`.
+      #
+      # String interpolation is always kept in double quotes.
+      #
+      # Note: `Lint/SymbolConversion` can be used in parallel to ensure that symbols
+      # are not quoted that don't need to be. This cop is for configuring the quoting
+      # style to use for symbols that require quotes.
+      #
+      # @example EnforcedStyle: same_as_string_literals (default) / single_quotes
+      #   # bad
+      #   :"abc-def"
+      #
+      #   # good
+      #   :'abc-def'
+      #   :"#{str}"
+      #   :"a\'b"
+      #
+      # @example EnforcedStyle: double_quotes
+      #   # bad
+      #   :'abc-def'
+      #
+      #   # good
+      #   :"abc-def"
+      #   :"#{str}"
+      #   :"a\'b"
+      class QuotedSymbols < Base
+        include ConfigurableEnforcedStyle
+        include SymbolHelp
+        include StringLiteralsHelp
+        extend AutoCorrector
+
+        MSG_SINGLE = "Prefer single-quoted symbols when you don't need string interpolation " \
+          'or special symbols.'
+        MSG_DOUBLE = 'Prefer double-quoted symbols unless you need single quotes to ' \
+          'avoid extra backslashes for escaping.'
+
+        def on_sym(node)
+          return unless quoted?(node)
+
+          message = style == :single_quotes ? MSG_SINGLE : MSG_DOUBLE
+
+          if wrong_quotes?(node)
+            add_offense(node, message: message) do |corrector|
+              opposite_style_detected
+              autocorrect(corrector, node)
+            end
+          else
+            correct_style_detected
+          end
+        end
+
+        private
+
+        def autocorrect(corrector, node)
+          str = if hash_key?(node)
+                  # strip quotes
+                  correct_quotes(node.source[1..-2])
+                else
+                  # strip leading `:` and quotes
+                  ":#{correct_quotes(node.source[2..-2])}"
+                end
+
+          corrector.replace(node, str)
+        end
+
+        def correct_quotes(str)
+          if style == :single_quotes
+            to_string_literal(str)
+          else
+            str.inspect
+          end
+        end
+
+        def style
+          return super unless super == :same_as_string_literals
+
+          string_literals_config = config.for_cop('Style/StringLiterals')
+          return :single_quotes unless string_literals_config['Enabled']
+
+          string_literals_config['EnforcedStyle'].to_sym
+        end
+
+        def alternative_style
+          (supported_styles - [style, :same_as_string_literals]).first
+        end
+
+        def quoted?(sym_node)
+          sym_node.source.match?(/\A:?(['"]).*?\1\z/m)
+        end
+
+        def wrong_quotes?(node)
+          return super if hash_key?(node)
+
+          super(node.source[1..-1])
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/style/string_literals.rb

@@ -29,6 +29,7 @@ module Style
       class StringLiterals < Base
         include ConfigurableEnforcedStyle
         include StringLiteralsHelp
+        include StringHelp
         extend AutoCorrector
 
         MSG_INCONSISTENT = 'Inconsistent quote style.'

lib/rubocop/cop/style/string_literals_in_interpolation.rb

@@ -22,6 +22,7 @@ module Style
       class StringLiteralsInInterpolation < Base
         include ConfigurableEnforcedStyle
         include StringLiteralsHelp
+        include StringHelp
         extend AutoCorrector
 
         def autocorrect(corrector, node)