Avoid forming intersections for dependent function types

Avoid forming an intersection when selecting the apply method
of a dependent function type.

Author: odersky

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

@@ -1171,19 +1171,18 @@ class Definitions {
     }
   }
 
-  object RefinedFunctionOf {
+  object RefinedFunctionOf:
+
     /** Matches a refined `PolyFunction`/`FunctionN[...]`/`ContextFunctionN[...]`.
      *  Extracts the method type type and apply info.
      */
-    def unapply(tpe: RefinedType)(using Context): Option[MethodOrPoly] = {
+    def unapply(tpe: RefinedType)(using Context): Option[MethodOrPoly] =
       tpe.refinedInfo match
         case mt: MethodOrPoly
-        if tpe.refinedName == nme.apply
-        && (tpe.parent.derivesFrom(defn.PolyFunctionClass) || isFunctionNType(tpe.parent)) =>
-          Some(mt)
+        if tpe.refinedName == nme.apply && isFunctionType(tpe.parent) => Some(mt)
         case _ => None
-    }
-  }
+
+  end RefinedFunctionOf
 
   object PolyFunctionOf {
 

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

@@ -845,7 +845,9 @@ object Types extends TypeUtils {
             safeIntersection = ctx.base.pendingMemberSearches.contains(name))
           joint match
             case joint: SingleDenotation
-            if isRefinedMethod && rinfo <:< joint.info =>
+            if isRefinedMethod
+              && (rinfo <:< joint.info
+                 || name == nme.apply && defn.isFunctionType(tp.parent)) =>
               // use `rinfo` to keep the right parameter names for named args. See i8516.scala.
               joint.derivedSingleDenotation(joint.symbol, rinfo, pre, isRefinedMethod)
             case _ =>
@@ -6479,7 +6481,7 @@ object Types extends TypeUtils {
     protected def needsRangeIfInvariant(refs: CaptureSet): Boolean = true
 
     override def mapCapturingType(tp: Type, parent: Type, refs: CaptureSet, v: Int): Type =
-      if v == 0 && needsRangeIfInvariant(refs) then
+      if v == 0 && needsRangeIfInvariant(refs) /* && false*/ then
         range(mapCapturingType(tp, parent, refs, -1), mapCapturingType(tp, parent, refs, 1))
       else
         super.mapCapturingType(tp, parent, refs, v)