Backport "Fix WUnused for accessible symbols that are renamed"

tests/neg-custom-args/fatal-warnings/i15503-scala2/scala2-t11681.scala

@@ -100,9 +100,9 @@ trait Anonymous {
 trait Context[A]
 trait Implicits {
   def f[A](implicit ctx: Context[A]) = answer // error
-  def g[A: Context] = answer // error
+  def g[A: Context] = answer // OK
 }
-class Bound[A: Context] // error
+class Bound[A: Context] // OK
 object Answers {
   def answer: Int = 42
 }

tests/neg-custom-args/fatal-warnings/i15503b.scala

@@ -75,7 +75,7 @@ package foo.scala2.tests:
 
   object Types {
     def l1() = {
-      object HiObject { def f = this } // error
+      object HiObject { def f = this } // OK
       class Hi { // error
         def f1: Hi = new Hi
         def f2(x: Hi) = x

tests/neg-custom-args/fatal-warnings/i15503f.scala

@@ -5,8 +5,9 @@ val default_int = 1
 
 def f1(a: Int) = a // OK
 def f2(a: Int) = 1 // OK
-def f3(a: Int)(using Int) = a // error
-def f4(a: Int)(using Int) = default_int // error
+def f3(a: Int)(using Int) = a // OK
+def f4(a: Int)(using Int) = default_int // OK
 def f6(a: Int)(using Int) = summon[Int] // OK
 def f7(a: Int)(using Int) = summon[Int] + a // OK
+def f8(a: Int)(using foo: Int) = a // error
 

tests/neg-custom-args/fatal-warnings/i15503g.scala

@@ -5,8 +5,8 @@ val default_int = 1
 
 def f1(a: Int) = a // OK
 def f2(a: Int) = default_int // error
-def f3(a: Int)(using Int) = a // error
-def f4(a: Int)(using Int) = default_int // error // error
+def f3(a: Int)(using Int) = a // OK
+def f4(a: Int)(using Int) = default_int // error
 def f6(a: Int)(using Int) = summon[Int] // error
 def f7(a: Int)(using Int) = summon[Int] + a // OK
 

tests/neg-custom-args/fatal-warnings/i15503i.scala

@@ -78,13 +78,13 @@ package foo.test.companionprivate:
 package foo.test.i16678:
   def foo(func: Int => String, value: Int): String = func(value) // OK
 
-  def run = 
+  def run =
     println(foo(number => number.toString, value = 5)) // OK
     println(foo(number => "<number>", value = 5)) // error
     println(foo(func = number => "<number>", value = 5)) // error
     println(foo(func = number => number.toString, value = 5)) // OK
     println(foo(func = _.toString, value = 5)) // OK
-    
+
 package foo.test.possibleclasses:
   case class AllCaseClass(
     k: Int, // OK
@@ -93,7 +93,7 @@ package foo.test.possibleclasses:
     s: Int, // error /* But not these */
     val t: Int, // OK
     private val z: Int // error
-  )       
+  )
 
   case class AllCaseUsed(
     k: Int, // OK
@@ -113,7 +113,7 @@ package foo.test.possibleclasses:
     s: Int, // error
     val t: Int, // OK
     private val z: Int // error
-  )      
+  )
 
   class AllUsed(
     k: Int, // OK
@@ -124,10 +124,137 @@ package foo.test.possibleclasses:
     private val z: Int // OK
   ) {
     def a = k + y + s + t + z
-  } 
+  }
 
 package foo.test.from.i16675:
   case class PositiveNumber private (i: Int) // OK
   object PositiveNumber:
-    def make(i: Int): Option[PositiveNumber] = //OK 
+    def make(i: Int): Option[PositiveNumber] = //OK
       Option.when(i >= 0)(PositiveNumber(i)) // OK
+
+package foo.test.i16822:
+  enum ExampleEnum {
+    case Build(context: String) // OK
+    case List // OK
+  }
+
+  def demo = {
+    val x = ExampleEnum.List // OK
+    println(x) // OK
+  }
+
+package foo.test.i16877:
+  import scala.collection.immutable.HashMap // OK
+  import scala.annotation.StaticAnnotation // OK
+
+  class ExampleAnnotation(val a: Object) extends StaticAnnotation // OK
+
+  @ExampleAnnotation(new HashMap()) // OK
+  class Test //OK
+
+package foo.test.i16926:
+  def hello(): Unit =
+    for {
+      i <- (0 to 10).toList
+      (a, b) = "hello" -> "world" // OK
+    } yield println(s"$a $b")
+
+package foo.test.i16925:
+  def hello =
+    for {
+      i <- 1 to 2 if true
+      _ = println(i) // OK
+    } yield ()
+
+package foo.test.i16863a:
+  import scala.quoted.*
+  def fn(using Quotes) =
+    val x = Expr(1)
+    '{ $x + 2 } // OK
+
+package foo.test.i16863b:
+  import scala.quoted.*
+  def fn[A](using Quotes, Type[A]) = // OK
+    val numeric = Expr.summon[Numeric[A]].getOrElse(???)
+    '{ $numeric.fromInt(3) } // OK
+
+package foo.test.i16863c:
+  import scala.quoted.*
+  def fn[A](expr: Expr[Any])(using Quotes) =
+    val imp = expr match
+      case '{ ${ _ }: a } => Expr.summon[Numeric[a]] // OK
+    println(imp)
+
+package foo.test.i16863d:
+  import scala.quoted.*
+  import scala.compiletime.asMatchable // OK
+  def fn[A](using Quotes, Type[A]) =
+    import quotes.reflect.*
+    val imp = TypeRepr.of[A].widen.asMatchable match
+      case Refinement(_,_,_) => ()
+    println(imp)
+
+package foo.test.i16679a:
+  object myPackage:
+    trait CaseClassName[A]:
+      def name: String
+    object CaseClassName:
+      trait CaseClassByStringName[A] extends CaseClassName[A]
+      import scala.deriving.Mirror
+      object CaseClassByStringName:
+        inline final def derived[A](using inline A: Mirror.Of[A]): CaseClassByStringName[A] =
+          new CaseClassByStringName[A]:
+            def name: String = A.toString
+
+  object secondPackage:
+    import myPackage.CaseClassName // OK
+    case class CoolClass(i: Int) derives CaseClassName.CaseClassByStringName
+    println(summon[CaseClassName[CoolClass]].name)
+
+package foo.test.i16679b:
+  object myPackage:
+    trait CaseClassName[A]:
+      def name: String
+
+    object CaseClassName:
+      import scala.deriving.Mirror
+      inline final def derived[A](using inline A: Mirror.Of[A]): CaseClassName[A] =
+        new CaseClassName[A]:
+          def name: String = A.toString
+
+  object Foo:
+    given x: myPackage.CaseClassName[secondPackage.CoolClass] = null
+
+  object secondPackage:
+    import myPackage.CaseClassName // OK
+    import Foo.x
+    case class CoolClass(i: Int)
+    println(summon[myPackage.CaseClassName[CoolClass]])
+
+package foo.test.i17156:
+  package a:
+    trait Foo[A]
+    object Foo:
+      inline def derived[T]: Foo[T] = new Foo{}
+
+  package b:
+    import a.Foo
+    type Xd[A] = Foo[A]
+
+  package c:
+    import b.Xd
+    trait Z derives Xd
+
+package foo.test.i17117:
+  package example {
+    object test1 {
+      val test = "test"
+    }
+
+    object test2 {
+
+      import example.test1 as t1
+
+      val test = t1.test
+    }
+  }

tests/neg-custom-args/fatal-warnings/i16930.scala

@@ -0,0 +1,22 @@
+// scalac: -Wunused:imports
+
+trait Outer:
+  trait Used
+  trait Unused
+
+object Test {
+  val outer: Outer = ???
+  import outer.{Used, Unused} // error
+  def foo(x: Any): Used = x.asInstanceOf[Used]
+}
+
+trait Outer1:
+  trait UnusedToo1
+  trait Unused1
+  def unusedToo1: UnusedToo1
+
+object Test1 {
+  val outer1: Outer1 = ???
+  import outer1.{Unused1, UnusedToo1} // error // error
+  def foo() = outer1.unusedToo1 // in this case UnusedToo1 is not used explicitly, only inferred
+}