Maximize removedTypeVar

Author: Blaisorblade

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -689,7 +689,8 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
       tvar =>
         !(ctx.typerState.constraint.entry(tvar.origin) `eq` tvar.origin.underlying) ||
         (tvar `eq` removeThisType.prefixTVar),
-      minimizeAll = false
+      minimizeAll = false,
+      maximizeAll = true
     )
 
     // If parent contains a reference to an abstract type, then we should

compiler/src/dotty/tools/dotc/typer/Inferencing.scala

@@ -114,7 +114,7 @@ object Inferencing {
           else {
             val minimize =
               force.minimizeAll ||
-              variance >= 0 && !(
+              !force.maximizeAll && variance >= 0 && !(
                 force == ForceDegree.noBottom &&
                 defn.isBottomType(ctx.typeComparer.approximation(tvar.origin, fromBelow = true)))
             if (minimize) instantiate(tvar, fromBelow = true)
@@ -466,9 +466,9 @@ trait Inferencing { this: Typer =>
 
 /** An enumeration controlling the degree of forcing in "is-dully-defined" checks. */
 @sharable object ForceDegree {
-  class Value(val appliesTo: TypeVar => Boolean, val minimizeAll: Boolean)
-  val none = new Value(_ => false, minimizeAll = false)
-  val all = new Value(_ => true, minimizeAll = false)
-  val noBottom = new Value(_ => true, minimizeAll = false)
+  class Value(val appliesTo: TypeVar => Boolean, val minimizeAll: Boolean, val maximizeAll: Boolean = false)
+  val none = new Value(_ => false, minimizeAll = false, maximizeAll = false)
+  val all = new Value(_ => true, minimizeAll = false, maximizeAll = false)
+  val noBottom = new Value(_ => true, minimizeAll = false, maximizeAll = false)
 }