Ignore BoundedWildcardType in erasure type map

This case can be triggered as illustrated in the test.

Author: adriaanm

src/reflect/scala/reflect/internal/transform/Erasure.scala

@@ -161,6 +161,11 @@ trait Erasure {
           }
         if (newParents eq parents) tp
         else ClassInfoType(newParents, decls, clazz)
+
+      // can happen while this map is being used before erasure (e.g. when reasoning about sam types)
+      // the regular mapOver will cause a class cast exception because TypeBounds don't erase to TypeBounds
+      case _: BoundedWildcardType => tp // skip
+
       case _ =>
         mapOver(tp)
     }

test/files/pos/sam_erasure_boundedwild.scala

@@ -0,0 +1,11 @@
+class Test {
+  trait Q[T] {
+    def toArray[T](x: Array[T]): Array[T]
+    def toArray(): Array[T]
+  }
+
+  def crashTyper: Array[_] = {
+   val x : Q[_] = ???
+   x.toArray // crashes while doing overload resolution
+  }
+}