[TypeChecker] SE-0347: Enable type inference from default expressions

include/swift/Basic/LangOptions.h

@@ -752,10 +752,6 @@ namespace swift {
     /// closures.
     bool EnableMultiStatementClosureInference = true;
 
-    /// Enable experimental support for generic parameter inference in
-    /// parameter positions from associated default expressions.
-    bool EnableTypeInferenceFromDefaultArguments = false;
-
     /// See \ref FrontendOptions.PrintFullConvention
     bool PrintFullConvention = false;
   };