Redefine hasCaptureConversionArg

Author: dwijnand

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

@@ -4470,8 +4470,6 @@ object Types {
 
     def hasWildcardArg(using Context): Boolean = args.exists(isBounds)
 
-    def hasCaptureConversionArg(using Context): Boolean = args.exists(_.typeSymbol == defn.TypeBox_CAP)
-
     def derivedAppliedType(tycon: Type, args: List[Type])(using Context): Type =
       if ((tycon eq this.tycon) && (args eq this.args)) this
       else tycon.appliedTo(args)

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

@@ -546,6 +546,10 @@ object Inferencing {
     case tp: AnnotatedType => tp.derivedAnnotatedType(captureWildcards(tp.parent), tp.annot)
     case _ => tp
   }
+
+  def hasCaptureConversionArg(tp: Type)(using Context): Boolean = tp match
+    case tp: AppliedType => tp.args.exists(_.typeSymbol == defn.TypeBox_CAP)
+    case _ => false
 }
 
 trait Inferencing { this: Typer =>

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

@@ -13,6 +13,7 @@ import Decorators._
 import Uniques._
 import inlines.Inlines
 import config.Printers.typr
+import Inferencing.*
 import ErrorReporting.*
 import util.SourceFile
 import TypeComparer.necessarySubType
@@ -495,18 +496,21 @@ object ProtoTypes {
         force = true)
       val targ1 = typer.adapt(targ, wideFormal, locked)
       if wideFormal eq formal then targ1
-      else targ1.tpe match
-        case tp: AppliedType if tp.hasCaptureConversionArg =>
-          stripCast(targ1).tpe match
-            case tp: AppliedType if tp.hasWildcardArg =>
-              errorTree(targ1,
-                em"""argument for by-name parameter is not a value
-                    |and contains wildcard arguments: $tp
-                    |
-                    |Assign it to a val and pass that instead.
-                    |""")
-            case _ => targ1
-        case _ => targ1
+      else checkNoWildcardCaptureForCBN(targ1)
+    }
+
+    def checkNoWildcardCaptureForCBN(targ1: Tree)(using Context): Tree = {
+      if hasCaptureConversionArg(targ1.tpe) then
+        stripCast(targ1).tpe match
+          case tp: AppliedType if tp.hasWildcardArg =>
+            errorTree(targ1,
+              em"""argument for by-name parameter is not a value
+                  |and contains wildcard arguments: $tp
+                  |
+                  |Assign it to a val and pass that instead.
+                  |""")
+          case _ => targ1
+      else targ1
     }
 
     /** The type of the argument `arg`, or `NoType` if `arg` has not been typed before

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

@@ -1568,7 +1568,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
                 else if ((tree.tpt `eq` untpd.ContextualEmptyTree) && mt.paramNames.isEmpty)
                   // Note implicitness of function in target type since there are no method parameters that indicate it.
                   TypeTree(defn.FunctionOf(Nil, mt.resType, isContextual = true, isErased = false))
-                else if mt.resType.match { case tp: AppliedType => tp.hasCaptureConversionArg case _ => false } then
+                else if hasCaptureConversionArg(mt.resType) then
                   errorTree(tree,
                     em"""cannot turn method type $mt into closure
                         |because it has capture conversion skolem types""")