rebase on current main branch

Author: olhotak

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

@@ -4182,18 +4182,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
       // convert function literal to SAM closure
       tree match {
         case closure(Nil, id @ Ident(nme.ANON_FUN), _)
-        if defn.isFunctionType(wtp) && !defn.isFunctionType(pt) && SAMType.isSamCompatible(wtp, pt) =>
-            case FlexibleType(tp) => tp match {
-              // recurse once inside
-              case SAMType(sam)
-              if wtp <:< sam.toFunctionType(isJava = pt.classSymbol.is(JavaDefined)) =>
-                // was ... && isFullyDefined(pt, ForceDegree.flipBottom)
-                // but this prevents case blocks from implementing polymorphic partial functions,
-                // since we do not know the result parameter a priori. Have to wait until the
-                  // body is typechecked.
-              return toSAM(tree)
-              case _ =>
-            }
+        if defn.isFunctionType(wtp) && !defn.isFunctionType(pt) && SAMType.isSamCompatible(wtp, pt.stripFlexible) =>
           // was ... && isFullyDefined(pt, ForceDegree.flipBottom)
           // but this prevents case blocks from implementing polymorphic partial functions,
           // since we do not know the result parameter a priori. Have to wait until the