Add run tests

Author: odersky

tests/run/i9928.check

@@ -0,0 +1,2 @@
+In foo
+In foo

tests/run/i9928.scala

@@ -0,0 +1,44 @@
+trait Magic[F]:
+  extension (x: Int) def read: F
+
+trait LowPrio:
+  given Magic[String]:
+    extension(x: Int) def read: String =
+      println("In string")
+      s"$x"
+
+object test1:
+  object Magic extends LowPrio
+
+  opaque type Foo = String
+  object Foo extends LowPrio:
+    import Magic.{given _}
+    def apply(s: String): Foo = s
+
+    given Magic[Foo]:
+      extension (x: Int) def read: Foo =
+        println("In foo")
+        Foo(s"$x")
+
+    def test: Unit =
+      (3.read: Foo)
+
+object test2:
+  object Magic extends LowPrio:
+    given Magic[Foo]:
+      extension (x: Int) def read: Foo =
+        println("In foo")
+        Foo(s"$x")
+
+  opaque type Foo = String
+  object Foo extends LowPrio:
+    import Magic.{given _}
+    def apply(s: String): Foo = s
+
+    def test: Unit =
+      (3.read: Foo)
+
+
+@main def Test =
+  test1.Foo.test
+  test2.Foo.test