Handle imports in path checks.

If `T` is a member of `p` then

    { import p._; ... T ... }

should be checked in the same way as

    { ... p.T ... }

Author: odersky

src/dotty/tools/dotc/typer/Typer.scala

@@ -274,6 +274,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
 
     val tree1 = ownType match {
       case ownType: NamedType if !prefixIsElidable(ownType) =>
+        checkRealizable(ownType.prefix, tree.pos)
         ref(ownType).withPos(tree.pos)
       case _ =>
         tree.withType(ownType)
@@ -991,6 +992,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     val impl1 = cpy.Template(impl)(constr1, parents1, self1, body1)
       .withType(dummy.nonMemberTermRef)
     checkVariance(impl1)
+    if (!cls.is(AbstractOrTrait)) checkRealizableBounds(cls.typeRef, cdef.pos)
     assignType(cpy.TypeDef(cdef)(name, impl1, Nil), cls)
 
     // todo later: check that

test/dotc/tests.scala

@@ -156,7 +156,7 @@ class tests extends CompilerTest {
   @Test def neg_i705 = compileFile(negDir, "i705-inner-value-class", xerrors = 7)
   @Test def neg_i866 = compileFile(negDir, "i866", xerrors = 2)
   @Test def neg_i974 = compileFile(negDir, "i974", xerrors = 2)
-  @Test def neg_i1050 = compileFile(negDir, "i1050", xerrors = 6)
+  @Test def neg_i1050 = compileFile(negDir, "i1050", xerrors = 8)
   @Test def neg_i1050a = compileFile(negDir, "i1050a", xerrors = 2)
   @Test def neg_moduleSubtyping = compileFile(negDir, "moduleSubtyping", xerrors = 4)
   @Test def neg_escapingRefs = compileFile(negDir, "escapingRefs", xerrors = 2)

tests/neg/i1050.scala

@@ -40,7 +40,7 @@ object Tiark1 {
     trait B { type L >: Any}
     trait U {
       lazy val p: B
-      def brand(x: Any): p.L = x // error: not final
+      def brand(x: Any): p.L = x // error: nonfinal lazy
     }
     trait V extends U {
       lazy val p: A & B = ???
@@ -54,7 +54,7 @@ object Tiark2 {
     trait U {
       type X <: B
       lazy val p: X
-      def brand(x: Any): p.L = x // error: not final
+      def brand(x: Any): p.L = x // error: nonfinal lazy
     }
     trait V extends U {
       type X = B & A
@@ -70,7 +70,7 @@ object Tiark3 {
       type X <: B
       def p2: X
       final lazy val p: X = p2
-      def brand(x: Any): p.L = x
+      def brand(x: Any): p.L = x // error: underlying not concrete
     }
     trait V extends U {
       type X = B with A
@@ -79,20 +79,18 @@ object Tiark3 {
     val v = new V {}
     v.brand("boom!"): Nothing
 }
-/*
 object Import {
     trait A { type L <: Nothing }
     trait B { type L >: Any}
     trait U {
-      val p: B
-      def brand(x: Any): p.L = x // error: not final
-      locally { import p._
+      lazy val p: B
+      locally { val x: p.L = ??? } // error: nonfinal lazy
+      locally {
+        import p._
+        val x: L = ??? // error: nonfinal lazy
       }
     }
     trait V extends U {
       lazy val p: A & B = ???
-    }
-    val v = new V {}
-    v.brand("boom!")
 }
-*/
+