New subtype constraint maintenance algorithm.

Objective: Avoid cycles by detecting all cases where

    A <: B and B <: A

and removing those cases by unifuing A and B.

Cycles need to be avoided because they lead to deep subtype recursions.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/util/SourceFile.scala b/src/dotty/tools/dotc/util/SourceFile.scala
index 5691ddcb8..4e1eb224a 100644
--- a/src/dotty/tools/dotc/util/SourceFile.scala
+++ b/src/dotty/tools/dotc/util/SourceFile.scala
@@ -125,6 +125,8 @@ case class SourceFile(file: AbstractFile, content: Array[Char]) {
     }
     col + 1
   }
+
+  override def toString = file.toString
 }
 
 object NoSource extends SourceFile("<no source>", Nil) {