[Fix #10148] Fix Style/QuotedSymbols handling escaped characters in…

…correctly.

Two cases are improved here:
1. Escaped double quotes (`\"`) within a double-quoted string are handled correctly (replaced with an unescaped double quote) when converting to a single-quoted string.
2. Escaped backslashes (`\\`) are treated properly and not doubled for both single- and double-quoted strings.

changelog/fix_fix_stylequotedsymbols_handling_escaped.md

@@ -0,0 +1 @@
+* [#10148](https://github.com/rubocop/rubocop/issues/10148): Fix `Style/QuotedSymbols` handling escaped characters incorrectly. ([@dvandersluis][])

lib/rubocop/cop/mixin/string_literals_help.rb

@@ -13,7 +13,11 @@ def wrong_quotes?(src_or_node)
         if style == :single_quotes
           !double_quotes_required?(src)
         else
-          !/" | \\[^'\\] | \#[@{$]/x.match?(src)
+          # The string needs single quotes if:
+          # 1. It contains a double quote
+          # 2. It contains text that would become an escape sequence with double quotes
+          # 3. It contains text that would become an interpolation with double quotes
+          !/" | (?<!\\)\\[abcefMnrtuUx0-7] | \#[@{$]/x.match?(src)
         end
       end
     end

lib/rubocop/cop/style/quoted_symbols.rb

@@ -76,11 +76,14 @@ def hash_colon_key?(node)
         end
 
         def correct_quotes(str)
-          if style == :single_quotes
-            to_string_literal(str)
-          else
-            str.inspect
-          end
+          correction = if style == :single_quotes
+                         to_string_literal(str)
+                       else
+                         str.gsub("\\'", "'").inspect
+                       end
+
+          # The conversion process doubles escaped slashes, so they have to be reverted
+          correction.gsub('\\\\', '\\')
         end
 
         def style

lib/rubocop/cop/util.rb

@@ -113,7 +113,8 @@ def to_string_literal(string)
         if needs_escaping?(string) && compatible_external_encoding_for?(string)
           string.inspect
         else
-          "'#{string.gsub('\\') { '\\\\' }}'"
+          # In a single-quoted strings, double quotes don't need to be escaped
+          "'#{string.gsub('\"', '"').gsub('\\') { '\\\\' }}'"
         end
       end
 

spec/rubocop/cop/style/quoted_symbols_spec.rb

@@ -113,6 +113,34 @@
       RUBY
     end
 
+    it 'registers an offense and corrects for an escaped quote within double quotes' do
+      expect_offense(<<~'RUBY')
+        :"my\"quote"
+        ^^^^^^^^^^^^ Prefer single-quoted symbols when you don't need string interpolation or special symbols.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        :'my"quote'
+      RUBY
+    end
+
+    it 'registers an offense and corrects escape characters properly' do
+      expect_offense(<<~'RUBY')
+        :"foo\\bar"
+        ^^^^^^^^^^^ Prefer single-quoted symbols when you don't need string interpolation or special symbols.
+      RUBY
+
+      expect_correction(<<~'RUBY')
+        :'foo\\bar'
+      RUBY
+    end
+
+    it 'accepts single quoted symbol with an escaped quote' do
+      expect_no_offenses(<<~'RUBY')
+        :'o\'clock'
+      RUBY
+    end
+
     context 'hash with hashrocket style' do
       it 'accepts properly quoted symbols' do
         expect_no_offenses(<<~RUBY)
@@ -213,6 +241,34 @@
       RUBY
     end
 
+    it 'registers an offense and corrects for an escaped quote within single quotes' do
+      expect_offense(<<~'RUBY')
+        :'o\'clock'
+        ^^^^^^^^^^^ Prefer double-quoted symbols unless you need single quotes to avoid extra backslashes for escaping.
+      RUBY
+
+      expect_correction(<<~'RUBY')
+        :"o'clock"
+      RUBY
+    end
+
+    it 'registers an offense and corrects escape characters properly' do
+      expect_offense(<<~'RUBY')
+        :'foo\\bar'
+        ^^^^^^^^^^^ Prefer double-quoted symbols unless you need single quotes to avoid extra backslashes for escaping.
+      RUBY
+
+      expect_correction(<<~'RUBY')
+        :"foo\\bar"
+      RUBY
+    end
+
+    it 'accepts double quoted symbol with an escaped quote' do
+      expect_no_offenses(<<~'RUBY')
+        :"my\"quote"
+      RUBY
+    end
+
     context 'hash with hashrocket style' do
       it 'accepts properly quoted symbols' do
         expect_no_offenses(<<~RUBY)

spec/rubocop/cop/style/string_literals_spec.rb

@@ -157,6 +157,17 @@
       RUBY
     end
 
+    it 'registers an offense for "\\"' do
+      expect_offense(<<~'RUBY')
+        "\\"
+        ^^^^ Prefer single-quoted strings when you don't need string interpolation or special symbols.
+      RUBY
+
+      expect_correction(<<~'RUBY')
+        '\\'
+      RUBY
+    end
+
     it 'registers an offense for words with non-ascii chars' do
       expect_offense(<<~RUBY)
         "España"