SI-6363 removes scala.reflect.base

As the experience has shown, there's no need for a separate layer of reflection
in scala-library.jar. Therefore I'm putting an end to it.

1 files changed, 26 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/api/TypeCreator.scala b/src/reflect/scala/reflect/api/TypeCreator.scala
new file mode 100644
index 0000000000..cc6d38c548
--- /dev/null
+++ b/src/reflect/scala/reflect/api/TypeCreator.scala
@@ -0,0 +1,26 @@
+package scala.reflect
+package api
+
+/** A mirror-aware factory for types.
+ *
+ * In the reflection API, artifacts are specific to universes and
+ * symbolic references used in artifacts (e.g. `scala.Int`) are resolved by mirrors.
+ *
+ * Therefore to build a type one needs to know a universe that the type is going to be bound to
+ * and a mirror that is going to resolve symbolic references (e.g. to determine that `scala.Int`
+ * points to a core class `Int` from scala-library.jar).
+ *
+ * `TypeCreator` implements this notion by providing a standalone type factory.
+ *
+ * This is immediately useful for type tags. When the compiler creates a type tag,
+ * the end result needs to make sense in any mirror. That's because the compiler knows
+ * the universe it's creating a type tag for (since `TypeTag` is path-dependent on a universe),
+ * but it cannot know in advance the mirror to instantiate the result in (e.g. on JVM
+ * it doesn't know what classloader use to resolve symbolic names in the type tag).
+ *
+ * Due to a typechecker restriction (no eta-expansion for dependent method types),
+ * `TypeCreator` can't have a functional type, so it's implemented as class with an apply method.
+ */
+abstract class TypeCreator {
+  def apply[U <: Universe with Singleton](m: MirrorOf[U]): U # Type
+}