Fix pickling tests failing with smarter tpd.

This also seems to be a reason why Ycheck:front fails.

typeAssigner is REMOVING partial evaluation that typer did
when you copy a tree. It means that types would be different if
you test pickling.

Temporary(permanent) solution: don't print constant types in pickling.

Author: DarkDimius

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -473,33 +473,27 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
     }
 
     override def Apply(tree: Tree)(fun: Tree, args: List[Tree])(implicit ctx: Context): Apply = {
-      if (ctx.settings.optimise.value) {
-        val untyped = untpd.cpy.Apply(tree)(fun, args)
-        val typed   = ta.assignType(untyped, fun, args)
-        if (untyped.ne(tree))
-          typed
-        else
-          tree.asInstanceOf[Apply]
-      } else {
-        ta.assignType(untpd.cpy.Apply(tree)(fun, args), fun, args)
-      }
+      val untyped = untpd.cpy.Apply(tree)(fun, args)
+      val typed = ta.assignType(untyped, fun, args)
+      if (untyped.ne(tree))
+        typed
+      else
+        tree.asInstanceOf[Apply]
     }
-      // Note: Reassigning the original type if `fun` and `args` have the same types as before
+
+    // Note: Reassigning the original type if `fun` and `args` have the same types as before
       // does not work here: The computed type depends on the widened function type, not
       // the function type itself. A treetransform may keep the function type the
       // same but its widened type might change.
 
     override def TypeApply(tree: Tree)(fun: Tree, args: List[Tree])(implicit ctx: Context): TypeApply = {
-      if (ctx.settings.optimise.value) {
-        val untyped = untpd.cpy.TypeApply(tree)(fun, args)
-        val typed   = ta.assignType(untyped, fun, args)
-        if (untyped.ne(tree))
-          typed
-        else
-          tree.asInstanceOf[TypeApply]
-      } else {
-        ta.assignType(untpd.cpy.TypeApply(tree)(fun, args), fun, args)
-      }
+      val untyped = untpd.cpy.TypeApply(tree)(fun, args)
+      val typed = ta.assignType(untyped, fun, args)
+      if (untyped.ne(tree))
+        typed
+      else
+        tree.asInstanceOf[TypeApply]
+
     }
       // Same remark as for Apply
 
@@ -535,16 +529,12 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
     }
 
     override def Closure(tree: Tree)(env: List[Tree], meth: Tree, tpt: Tree)(implicit ctx: Context): Closure = {
-      if (ctx.settings.optimise.value) {
-        val untyped = untpd.cpy.Closure(tree)(env, meth, tpt)
-        val typed   = ta.assignType(untyped, meth, tpt)
-        if (untyped.ne(tree))
-          typed
-        else
-          tree.asInstanceOf[Closure]
-      } else {
-        ta.assignType(untpd.cpy.Closure(tree)(env, meth, tpt), meth, tpt)
-      }
+      val untyped = untpd.cpy.Closure(tree)(env, meth, tpt)
+      val typed = ta.assignType(untyped, meth, tpt)
+      if (untyped.ne(tree))
+        typed
+      else
+        tree.asInstanceOf[Closure]
     }
       // Same remark as for Apply
 

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -53,7 +53,9 @@ class PlainPrinter(_ctx: Context) extends Printer {
         case AndType(tp1, tp2) =>
           homogenize(tp1) & homogenize(tp2)
         case OrType(tp1, tp2) =>
-          homogenize(tp1) | homogenize(tp2)
+          if (tp1.classSymbol.id > tp2.classSymbol.id)
+            homogenize(tp1) | homogenize(tp2)
+          else homogenize(tp2) | homogenize(tp1)
         case tp: SkolemType =>
           homogenize(tp.info)
         case tp: LazyRef =>

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -124,7 +124,10 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
             toTextTuple(args.init)
         ("implicit " provided isImplicit) ~ argStr ~ " => " ~ argText(args.last)
       }
-    homogenize(tp) match {
+    val htp = homogenize(tp)
+    htp match {
+      case x: ConstantType if homogenizedView =>
+        return toText(x.widen)
       case AppliedType(tycon, args) =>
         val cls = tycon.typeSymbol
         if (tycon.isRepeatedParam) return toTextLocal(args.head) ~ "*"