Make sure errorTermTrees have positions

Crashed the parser before, because errorTermTree
did not have a position.

Author: odersky

src/dotty/tools/dotc/parsing/Parsers.scala

@@ -269,7 +269,8 @@ object Parsers {
     def acceptStatSepUnlessAtEnd(altEnd: Token = EOF) =
       if (!isStatSeqEnd && in.token != altEnd) acceptStatSep()
 
-    def errorTermTree    = atPos(in.offset) { Literal(Constant(null)) }
+    def errorTermTree =
+      Literal(Constant(null)).withPos(Position(in.offset, in.offset))
 
     private var inFunReturnType = false
     private def fromWithinReturnType[T](body: => T): T = {

tests/neg/i1705.scala

@@ -0,0 +1,24 @@
+object DepBug {
+  class A {
+    class B
+    def mkB = new B
+    def m(b: B) = b
+  }
+  trait Dep {
+    val a: A
+    val b: a.B
+  }
+  val dep = new {
+    val a = new A
+    val b = a mkB
+  }
+  def useDep(d: Dep) {  // error: procedure syntax
+    import d._
+    a m (b)
+  }
+  {   // error: Null does not take parameters (follow on)
+    import dep._
+    a m (b)
+  }
+  dep.a m (dep b) // error (follow on)
+}