Various tweaks

- Swap order of subtype tests

The theory is that if two refined types have the same refined name, then
they are likely to be of related classes. So it seems more fruitful to
check the argument before the typeconstructor because that way we test
the part that's more likely to fail first. Rough observations seem to
indicate a 3% improvement in the junit test time.

- Cleanups

Drop some unnecessary cases; improve comments.

- Smarter handling of LazyRefs in betaReduce

Try to combine type constructor and arguments under a
common LazyRef.

- Optimize RecType/RecType comparisons
- Fix compareHkLambda, make it check variances.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/typer/Inferencing.scala b/src/dotty/tools/dotc/typer/Inferencing.scala
index 3b79d7c4c..2b37fa36c 100644
--- a/src/dotty/tools/dotc/typer/Inferencing.scala
+++ b/src/dotty/tools/dotc/typer/Inferencing.scala
@@ -218,7 +218,7 @@ object Inferencing {
     val qualifies = (tvar: TypeVar) =>
       (tree contains tvar.owningTree) || ownedBy.exists && tvar.owner == ownedBy
     def interpolate() = Stats.track("interpolateUndetVars") {
-      val tp = tree.tpe.widen  // TODO add `.BetaReduce` ?
+      val tp = tree.tpe.widen
       constr.println(s"interpolate undet vars in ${tp.show}, pos = ${tree.pos}, mode = ${ctx.mode}, undets = ${constraint.uninstVars map (tvar => s"${tvar.show}@${tvar.owningTree.pos}")}")
       constr.println(s"qualifying undet vars: ${constraint.uninstVars filter qualifies map (tvar => s"$tvar / ${tvar.show}")}, constraint: ${constraint.show}")