Fix issue with explicit type for parameters

- Before this fix, trying to remove the [Int] from the option resulted in: cannot infer type; expected type <?> is not fully defined
  To avoid this, we simply wrap the pre-typed arguments in TypedSplices

Author: timotheeandres

compiler/src/dotty/tools/dotc/ast/MainProxies.scala

@@ -184,16 +184,16 @@ object MainProxies {
     /** Turns an annotation (e.g. `@main(40)`) into an instance of the class (e.g. `new scala.main(40)`). */
     def instanciateAnnotation(annot: Annotation): Tree =
       val argss = {
-        def recurse(t: Tree, acc: List[List[Tree]]): List[List[Tree]] = t match {
-          case Apply(t, args: List[Tree]) => recurse(t, extractArgs(args) :: acc)
+        def recurse(t: tpd.Tree, acc: List[List[Tree]]): List[List[Tree]] = t match {
+          case Apply(t, args: List[tpd.Tree]) => recurse(t, extractArgs(args) :: acc)
           case _ => acc
         }
 
-        def extractArgs(args: List[Tree]): List[Tree] =
+        def extractArgs(args: List[tpd.Tree]): List[Tree] =
           args.flatMap {
-            case Typed(SeqLiteral(varargs, _), _) => varargs
-            case arg @ Select(_, name) => if name.is(DefaultGetterName) then List() else List(arg)
-            case arg => List(arg)
+            case Typed(SeqLiteral(varargs, _), _) => varargs.map(arg => TypedSplice(arg))
+            case arg @ Select(_, name) => if name.is(DefaultGetterName) then List() else List(TypedSplice(arg))
+            case arg => List(TypedSplice(arg))
           }
 
         recurse(annot.tree, Nil)

tests/run/main-annotation-homemade-annot-5.scala

@@ -1,6 +1,6 @@
 import scala.annotation.MainAnnotation
 
-@mainManyArgs(Some[Int](1)) def foo() = println("Hello world!")
+@mainManyArgs(Some(1)) def foo() = println("Hello world!")
 @mainManyArgs(None) def bar() = println("Hello world!")
 
 object Test: