Avoid NPE when printing TyperStates

odersky · odersky · commit 539c203dbf94 · 2017-10-04T20:52:55.000+02:00
diff --git a/compiler/src/dotty/tools/dotc/core/TyperState.scala b/compiler/src/dotty/tools/dotc/core/TyperState.scala
@@ -165,5 +165,6 @@ class TyperState(previous: TyperState /* | Null */) extends DotClass with Showab
 
   override def toText(printer: Printer): Text = constraint.toText(printer)
 
-  def hashesStr: String = hashCode.toString + " -> " + previous.hashesStr
+  def hashesStr: String =
+    if (previous == null) "" else hashCode.toString + " -> " + previous.hashesStr
 }

Original file line number	Diff line number	Diff line change
`@@ -165,5 +165,6 @@ class TyperState(previous: TyperState /* \| Null */) extends DotClass with Showab`
`165`	`165`
`166`	`166`	`override def toText(printer: Printer): Text = constraint.toText(printer)`
`167`	`167`
`168`		`- def hashesStr: String = hashCode.toString + " -> " + previous.hashesStr`
	`168`	`+ def hashesStr: String =`
	`169`	`+ if (previous == null) "" else hashCode.toString + " -> " + previous.hashesStr`
`169`	`170`	`}`