Fix #8397: Make context parameters of given instances protected

Author: odersky

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -3508,7 +3508,7 @@ object Parsers {
             possibleTemplateStart()
             val tparams1 = tparams.map(tparam => tparam.withMods(tparam.mods | PrivateLocal))
             val vparamss1 = vparamss.map(_.map(vparam =>
-              vparam.withMods(vparam.mods &~ Param | ParamAccessor | PrivateLocal)))
+              vparam.withMods(vparam.mods &~ Param | ParamAccessor | Protected)))
             val templ = templateBodyOpt(makeConstructor(tparams1, vparamss1), parents, Nil)
             if tparams.isEmpty && vparamss.isEmpty then ModuleDef(name, templ)
             else TypeDef(name.toTypeName, templ)

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

@@ -510,8 +510,8 @@ object Checking {
           var tp1 =
             if (isLeaked(tp.symbol)) {
               errors =
-                (() => em"non-private ${sym.showLocated} refers to private ${tp.symbol}\nin its type signature ${sym.info}") ::
-                errors
+                (() => em"non-private ${sym.showLocated} refers to private ${tp.symbol}\nin its type signature ${sym.info}")
+                :: errors
               tp
             }
             else mapOver(tp)

tests/pos/i8397.scala

@@ -0,0 +1,3 @@
+given foo(using x: Int) as AnyRef:
+  type T = x.type
+