New modularity language import

Author: odersky

library/src/scala/runtime/stdLibPatches/language.scala

@@ -91,6 +91,17 @@ object language:
     @compileTimeOnly("`into` can only be used at compile time in import statements")
     object into
 
+    /** Experimental support for new features for better modularity, including
+     *   - better tracking of dependencies through classes
+     *   - better usability of context bounds
+     *   - better syntax and conventions for type classes
+     *   - ability to merge exported types in intersections
+     *
+     *  @see [[https://dotty.epfl.ch/docs/reference/experimental/modularity]]
+     */
+    @compileTimeOnly("`modularity` can only be used at compile time in import statements")
+    object modularity
+
     /** Was needed to add support for relaxed imports of extension methods.
       * The language import is no longer needed as this is now a standard feature since SIP was accepted.
       * @see [[http://dotty.epfl.ch/docs/reference/contextual/extension-methods]]