Improve error message

Blaisorblade · Blaisorblade · commit c9b97809116c · 2018-04-09T13:49:22.000+02:00
diff --git a/compiler/src/dotty/tools/dotc/core/OrderingConstraint.scala b/compiler/src/dotty/tools/dotc/core/OrderingConstraint.scala
@@ -526,7 +526,7 @@ class OrderingConstraint(private val boundsMap: ParamBounds,
         case (e1: TypeBounds, _) if e1 contains e2 => e2
         case (tv1: TypeVar, tv2: TypeVar) if tv1.instanceOpt eq tv2.instanceOpt => e1
         case _ =>
-          throw new AssertionError(i"cannot merge $this with $other")
+          throw new AssertionError(i"cannot merge $this with $other, mergeEntries($e1, $e2) failed")
       }
 
     val that = other.asInstanceOf[OrderingConstraint]

Original file line number	Diff line number	Diff line change
`@@ -526,7 +526,7 @@ class OrderingConstraint(private val boundsMap: ParamBounds,`
`526`	`526`	`case (e1: TypeBounds, _) if e1 contains e2 => e2`
`527`	`527`	`case (tv1: TypeVar, tv2: TypeVar) if tv1.instanceOpt eq tv2.instanceOpt => e1`
`528`	`528`	`case _ =>`
`529`		`- throw new AssertionError(i"cannot merge $this with $other")`
	`529`	`+ throw new AssertionError(i"cannot merge $this with $other, mergeEntries($e1, $e2) failed")`
`530`	`530`	`}`
`531`	`531`
`532`	`532`	`val that = other.asInstanceOf[OrderingConstraint]`