Tightening of position handlng

1) endPos works now even for NoPosition.
2) On the other hand, there's an assertion in Typer.typed which requires every non-empty tree that's type checked in a globally committable context to have a defined position.

Some fixes were needed to make the tests pass the new assert.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/TyperState.scala b/src/dotty/tools/dotc/core/TyperState.scala
index f46c58c90..455320ba8 100644
--- a/src/dotty/tools/dotc/core/TyperState.scala
+++ b/src/dotty/tools/dotc/core/TyperState.scala
@@ -41,6 +41,9 @@ class TyperState(val reporter: Reporter) extends DotClass with Showable {
   /** Is it allowed to commit this state? */
   def isCommittable: Boolean = false
 
+  /** Can this state be transitively committed until the top-level? */
+  def isGlobalCommittable: Boolean = false
+
   override def toText(printer: Printer): Text = "ImmutableTyperState"
 }
 
@@ -55,6 +58,10 @@ extends TyperState(reporter) {
   override def fresh(isCommittable: Boolean): TyperState =
     new MutableTyperState(this, new StoreReporter, isCommittable)
 
+  override val isGlobalCommittable =
+    isCommittable &&
+    (!previous.isInstanceOf[MutableTyperState] || previous.isGlobalCommittable)
+
   /** Commit typer state so that its information is copied into current typer state
    *  In addition (1) the owning state of undetermined or temporarily instantiated
    *  type variables changes from this typer state to the current one. (2) Variables