Fix typing of generated context bound refinements

Avoid accidental binding to self

# Conflicts:
#	compiler/src/dotty/tools/dotc/typer/Typer.scala

Author: odersky

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

@@ -2211,7 +2211,8 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
     if tycon.tpe.typeParams.nonEmpty then
       typed(untpd.AppliedTypeTree(tyconSplice, tparam :: Nil))
     else if Feature.enabled(modularity) && tycon.tpe.member(tpnme.Self).symbol.isAbstractType then
-      typed(untpd.RefinedTypeTree(tyconSplice, List(untpd.TypeDef(tpnme.Self, tparam))))
+      val tparamSplice = untpd.TypedSplice(typedExpr(tparam))
+      typed(untpd.RefinedTypeTree(tyconSplice, List(untpd.TypeDef(tpnme.Self, tparamSplice))))
     else
       errorTree(tree,
         em"""Illegal context bound: ${tycon.tpe} does not take type parameters and

tests/pos/hylolib-extract.scala

@@ -1,17 +1,25 @@
 //> using options -language:experimental.modularity -source future
 package hylotest
 
-trait Value[Self]
+trait Value:
+  type Self
+  extension (self: Self) def eq(other: Self): Boolean
 
 /** A collection of elements accessible by their position. */
-trait Collection[Self]:
+trait Collection:
+  type Self
 
   /** The type of the elements in the collection. */
   type Element: Value
 
 class BitArray
 
-given Value[Boolean] {}
+given Boolean is Value:
+  extension (self: Self) def eq(other: Self): Boolean =
+    self == other
 
-given Collection[BitArray] with
+given BitArray is Collection:
   type Element = Boolean
+
+extension [Self: Value](self: Self)
+  def neq(other: Self): Boolean = !self.eq(other)