Don't freeze input strings

See 34321e4a433bb7eef48fd743286601403f8f7d82 for background on
ImmutableString vs String.

Our String type cannot delegate typecasting to ImmutableString, because
the latter freezes its input: duplicating the value after that gives us
an unfrozen result, but still mutates the originally passed object.

1 files changed, 6 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/type/string.rb b/activemodel/lib/active_model/type/string.rb
index c7e0208a5a..850cab962b 100644
--- a/activemodel/lib/active_model/type/string.rb
+++ b/activemodel/lib/active_model/type/string.rb
@@ -12,7 +12,12 @@ module ActiveModel
       private
 
         def cast_value(value)
-          ::String.new(super)
+          case value
+          when ::String then ::String.new(value)
+          when true then "t".freeze
+          when false then "f".freeze
+          else value.to_s
+          end
         end
     end
   end