wip

Author: soronpo

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

@@ -4017,9 +4017,8 @@ object Types {
 
     val declaredParamPrecises: List[Boolean]
     def paramPrecises(using Context): List[Boolean] =
-//      if declaredParamPrecises.isEmpty then paramInfos.map(_ => false)
-//      else
-        declaredParamPrecises
+      if declaredParamPrecises.isEmpty then paramNames.map(_ => false)
+      else declaredParamPrecises
 
     @threadUnsafe lazy val typeParams: List[LambdaParam] =
       paramNames.indices.toList.map(new LambdaParam(this, _))
@@ -4534,8 +4533,7 @@ object Types {
     def copyBoundType(bt: BT): Type = bt.paramRefs(paramNum)
     private var propagatedPrecise: Boolean = false
     protected[Types] def setPropagatedPrecise(p: Boolean): Unit = propagatedPrecise = p
-    override def isPrecise(using Context): Boolean =
-      propagatedPrecise || binder.paramPrecises.nonEmpty && binder.paramPrecises(paramNum)
+    override def isPrecise(using Context): Boolean = propagatedPrecise || binder.paramPrecises(paramNum)
     /** Optimized version of occursIn, avoid quadratic blowup when solving
      *  constraints over large ground types.
      */

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

@@ -290,7 +290,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
     def paramText(name: Name, tp: Type, precise: Boolean) =
       (if precise then "@precise " else "") ~ toText(name) ~ lambdaHash(lam) ~ toTextRHS(tp, isParameter = true)
     val precises = lam match
-      case pt: TypeLambda if pt.paramPrecises.nonEmpty => pt.paramPrecises
+      case pt: TypeLambda => pt.paramPrecises
       case _ => lam.paramNames.map(_ => false)
     Text(lam.paramNames.lazyZip(lam.paramInfos).lazyZip(precises).toList.map(paramText), ", ")
   }