Fix string literal autocorrect

changelog/fix_autocorrect_when_doublequotes_are.md

@@ -0,0 +1 @@
+* [#9751](https://github.com/rubocop/rubocop/pull/9751): `Style/StringLiteral` autocorrects `'\\'` into `"\\"`. ([@etiennebarrie][])

changelog/fix_dont_autocorrect_global_variable.md

@@ -0,0 +1 @@
+* [#9751](https://github.com/rubocop/rubocop/pull/9751): `Style/StringLiteral` doesn't autocorrect global variable interpolation. ([@etiennebarrie][])

lib/rubocop/cop/mixin/string_literals_help.rb

@@ -15,7 +15,7 @@ def wrong_quotes?(node)
         if style == :single_quotes
           !double_quotes_required?(src)
         else
-          !/" | \\[^'] | \#(@|\{)/x.match?(src)
+          !/" | \\[^'\\] | \#[@{$]/x.match?(src)
         end
       end
     end

spec/rubocop/cop/style/string_literals_spec.rb

@@ -206,10 +206,13 @@
       expect_offense(<<~'RUBY')
         '\''
         ^^^^ Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.
+        '\\'
+        ^^^^ Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.
       RUBY
 
       expect_correction(<<~'RUBY')
         "'"
+        "\\"
       RUBY
     end
 
@@ -261,10 +264,12 @@
         a = '\n'
         b = '"'
         c = '#{x}'
+        d = '#@x'
+        e = '#$x'
       RUBY
     end
 
-    it 'flags single quotes with plain # (not #@var or #{interpolation}' do
+    it 'flags single quotes with plain # (not #@var or #{interpolation} or #$global' do
       expect_offense(<<~RUBY)
         a = 'blah #'
             ^^^^^^^^ Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.