Fix tests for WUnused/disable for public defs

Author: szymon-rd

tests/neg-custom-args/fatal-warnings/i15503e.scala

@@ -14,7 +14,7 @@ object Foo {
 
 package scala2main.unused.args:
   object happyBirthday {
-    def main(args: Array[String]): Unit = println("Hello World") // error
+    def main(args: Array[String]): Unit = println("Hello World") // ok
   }
 
 package scala2main:
@@ -31,27 +31,27 @@ package scala3main:
 package foo.test.lambda.param:
   val default_val = 1
   val a = (i: Int) => i // OK
-  val b = (i: Int) => default_val // error
+  val b = (i: Int) => default_val // OK
   val c = (_: Int) => default_val // OK
 
 package foo.test.trivial:
   /* A twisted test from Scala 2 */
   class C {
     def answer: 42 = 42
     object X
-    def g0(x: Int) = ??? // OK
-    def f0(x: Int) = () // OK
-    def f1(x: Int) = throw new RuntimeException // OK
-    def f2(x: Int) = 42 // OK
-    def f3(x: Int): Option[Int] = None // OK
-    def f4(x: Int) = classOf[Int] // OK
-    def f5(x: Int) = answer + 27 // OK
-    def f6(x: Int) = X // OK
-    def f7(x: Int) = Y // OK
-    def f8(x: Int): List[C] = Nil // OK
-    def f9(x: Int): List[Int] = List(1,2,3,4) // error
-    def foo:Int = 32  // OK
-    def f77(x: Int) = foo // error
+    private def g0(x: Int) = ??? // OK
+    private def f0(x: Int) = () // OK
+    private def f1(x: Int) = throw new RuntimeException // OK
+    private def f2(x: Int) = 42 // OK
+    private def f3(x: Int): Option[Int] = None // OK
+    private def f4(x: Int) = classOf[Int] // OK
+    private def f5(x: Int) = answer + 27 // OK
+    private def f6(x: Int) = X // OK
+    private def f7(x: Int) = Y // OK
+    private def f8(x: Int): List[C] = Nil // OK
+    private def f9(x: Int): List[Int] = List(1,2,3,4) // error
+    private def foo:Int = 32  // OK
+    private def f77(x: Int) = foo // error
   }
   object Y