diff options
| -rw-r--r-- | src/dotty/tools/dotc/typer/EtaExpansion.scala | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/src/dotty/tools/dotc/typer/EtaExpansion.scala b/src/dotty/tools/dotc/typer/EtaExpansion.scala index 7c1130b83..394accd03 100644 --- a/src/dotty/tools/dotc/typer/EtaExpansion.scala +++ b/src/dotty/tools/dotc/typer/EtaExpansion.scala @@ -84,7 +84,7 @@ object EtaExpansion { case TypeApply(fn, targs) => cpy.TypeApply(tree)(liftApp(defs, fn), targs) case Select(pre, name) if isPureRef(tree) => - cpy.Select(tree)(liftApp(defs, pre), name) + cpy.Select(tree)(liftPrefix(defs, pre), name) case Block(stats, expr) => liftApp(defs ++= stats, expr) case New(tpt) => @@ -93,6 +93,18 @@ object EtaExpansion { lift(defs, tree) } + /** Lift prefix `pre` of an application `pre.f(...)` to + * + * val x0 = pre + * x0.f(...) + * + * unless `pre` is a `New` or `pre` is idempotent. + */ + def liftPrefix(defs: mutable.ListBuffer[Tree], tree: Tree)(implicit ctx: Context): Tree = tree match { + case New(_) => tree + case _ => if (isIdempotentExpr(tree)) tree else lift(defs, tree) + } + /** Eta-expanding a tree means converting a method reference to a function value. * @param tree The tree to expand * @param mt The type of the method reference |