Get rid of TypeState.hashesStr

Hashes ruin diffability; replace them with the serial `id` numbers.

Author: odersky

compiler/src/dotty/tools/dotc/core/ConstraintHandling.scala

@@ -85,19 +85,21 @@ trait ConstraintHandling {
     finally homogenizeArgs = saved
   }
 
+  private def location(implicit ctx: Context) = "" // i"in ${ctx.typerState.stateChainStr}" // use for debugging
+
   protected def addUpperBound(param: TypeParamRef, bound: Type): Boolean = {
     def description = i"constraint $param <: $bound to\n$constraint"
     if (bound.isRef(defn.NothingClass) && ctx.typerState.isGlobalCommittable) {
       def msg = s"!!! instantiated to Nothing: $param, constraint = ${constraint.show}"
       if (Config.failOnInstantiationToNothing) assert(false, msg)
       else ctx.log(msg)
     }
-    constr.println(i"adding $description in ${ctx.typerState.hashesStr}")
+    constr.println(i"adding $description$location")
     val lower = constraint.lower(param)
     val res =
       addOneBound(param, bound, isUpper = true) &&
       lower.forall(addOneBound(_, bound, isUpper = true))
-    constr.println(i"added $description = $res in ${ctx.typerState.hashesStr}")
+    constr.println(i"added $description = $res$location")
     res
   }
 
@@ -108,7 +110,7 @@ trait ConstraintHandling {
     val res =
       addOneBound(param, bound, isUpper = false) &&
       upper.forall(addOneBound(_, bound, isUpper = false))
-    constr.println(i"added $description = $res in ${ctx.typerState.hashesStr}")
+    constr.println(i"added $description = $res$location")
     res
   }
 
@@ -121,12 +123,12 @@ trait ConstraintHandling {
         val up2 = p2 :: constraint.exclusiveUpper(p2, p1)
         val lo1 = constraint.nonParamBounds(p1).lo
         val hi2 = constraint.nonParamBounds(p2).hi
-        constr.println(i"adding $description down1 = $down1, up2 = $up2 ${ctx.typerState.hashesStr}")
+        constr.println(i"adding $description down1 = $down1, up2 = $up2$location")
         constraint = constraint.addLess(p1, p2)
         down1.forall(addOneBound(_, hi2, isUpper = true)) &&
         up2.forall(addOneBound(_, lo1, isUpper = false))
       }
-    constr.println(i"added $description = $res ${ctx.typerState.hashesStr}")
+    constr.println(i"added $description = $res$location")
     res
   }
 

compiler/src/dotty/tools/dotc/core/TyperState.scala

@@ -18,13 +18,11 @@ object TyperState {
   @sharable private var nextId: Int = 0
 }
 
-class TyperState(previous: TyperState /* | Null */) extends DotClass with Showable {
+class TyperState(previous: TyperState /* | Null */) {
 
   val id = TyperState.nextId
   TyperState.nextId += 1
 
-  //assert(id != 146)
-
   private[this] var myReporter =
     if (previous == null) new ConsoleReporter() else previous.reporter
 
@@ -181,8 +179,7 @@ class TyperState(previous: TyperState /* | Null */) extends DotClass with Showab
       constraint = constraint.remove(poly)
   }
 
-  override def toText(printer: Printer): Text = s"TS[$id]"
+  override def toString: String = s"TS[$id]"
 
-  def hashesStr: String =
-    if (previous == null) "" else hashCode.toString + " -> " + previous.hashesStr
+  def stateChainStr: String = s"$this${if (previous == null) "" else previous.stateChainStr}"
 }