Remove adaptation of 0-arg methods under -Xsource:3.0

Get thee to a nullary, go. Farewell -Xfuture.

Ref scala/bug#8035

src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala

@@ -629,7 +629,7 @@ abstract class BTypes {
         // synchronization required to ensure the apply is finished
         // which populates info. ClassBType doesnt escape apart from via the map
         // and the object mutex is locked prior to insertion. See apply
-        this.synchronized()
+        this.synchronized {}
       assert(_info != null, s"ClassBType.info not yet assigned: $this")
       _info
     }

src/compiler/scala/tools/nsc/settings/ScalaSettings.scala

@@ -98,6 +98,8 @@ trait ScalaSettings extends AbsScalaSettings
   def isScala213: Boolean = source.value >= version213
   private[this] val version214 = ScalaVersion("2.14.0")
   def isScala214: Boolean = source.value >= version214
+  private[this] val version3_0 = ScalaVersion("3.0.0")
+  def isScala3: Boolean = source.value >= version3_0
 
   /**
    * -X "Advanced" settings

src/compiler/scala/tools/nsc/typechecker/Adaptations.scala

@@ -67,21 +67,22 @@ trait Adaptations {
       }
 
       if (args.isEmpty) {
-        if (settings.future)
-          context.error(t.pos, adaptWarningMessage("Adaptation of argument list by inserting () has been removed.", showAdaptation = false))
+        def msg(what: String): String = s"adaptation of an empty argument list by appending () is $what"
+        if (settings.isScala3)
+          context.error(t.pos, adaptWarningMessage(msg("unsupported"), showAdaptation = false))
         else {
-          val msg = "Adaptation of argument list by inserting () is deprecated: " + (
-          if (isLeakyTarget) "leaky (Object-receiving) target makes this especially dangerous."
-          else "this is unlikely to be what you want.")
-          context.deprecationWarning(t.pos, t.symbol, adaptWarningMessage(msg), "2.11.0")
+          context.deprecationWarning(t.pos, t.symbol, adaptWarningMessage(
+            msg("deprecated") + ": " + (
+              if (isLeakyTarget) "leaky (Object-receiving) target makes this especially dangerous"
+              else "this is unlikely to be what you want")), "2.11.0")
         }
       } else if (settings.warnAdaptedArgs)
         context.warning(t.pos, adaptWarningMessage(
           s"adapted the argument list to the expected ${args.size}-tuple: add additional parens instead")
         )
 
       // return `true` if the adaptation should be kept
-      !(args.isEmpty && settings.future)
+      !(args.isEmpty && settings.isScala3)
     }
   }
 }

test/files/jvm/future-spec.check

@@ -1 +0,0 @@
-warning: there was one deprecation warning (since 2.11.0); re-run with -deprecation for details

test/files/jvm/future-spec/FutureTests.scala

@@ -1,3 +1,5 @@
+/* scalac: -Xsource:3.0 */
+
 import scala.concurrent._
 import scala.concurrent.duration._
 import scala.concurrent.duration.Duration.Inf
@@ -39,7 +41,8 @@ class FutureTests extends MinimalScalaTest {
       val ms = new concurrent.TrieMap[Throwable, Unit]
       implicit val ec = scala.concurrent.ExecutionContext.fromExecutor(new java.util.concurrent.ForkJoinPool(), {
         t =>
-        ms += (t -> ())
+        val u = ()
+        ms += (t -> u)
       })
 
       class ThrowableTest(m: String) extends Throwable(m)

test/files/neg/checksensible.check

@@ -1,17 +1,29 @@
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 #partest java8
 checksensible.scala:47: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+=======
+checksensible.scala:45: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: Any.==(x$1: Any): Boolean
   given arguments: <none>
  after adaptation: Any.==((): Unit)
   () == ()
      ^
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 checksensible.scala:50: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+=======
+checksensible.scala:48: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: Object.!=(x$1: Any): Boolean
   given arguments: <none>
  after adaptation: Object.!=((): Unit)
   scala.runtime.BoxedUnit.UNIT != ()
                                ^
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 checksensible.scala:51: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+=======
+checksensible.scala:49: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: Any.!=(x$1: Any): Boolean
   given arguments: <none>
  after adaptation: Any.!=((): Unit)

test/files/neg/t4851.check

@@ -1,10 +1,10 @@
-S.scala:2: warning: Adaptation of argument list by inserting () is deprecated: leaky (Object-receiving) target makes this especially dangerous.
+S.scala:2: warning: adaptation of an empty argument list by appending () is deprecated: leaky (Object-receiving) target makes this especially dangerous
         signature: J(x: Any): J
   given arguments: <none>
  after adaptation: new J((): Unit)
   val x1 = new J
            ^
-S.scala:3: warning: Adaptation of argument list by inserting () is deprecated: leaky (Object-receiving) target makes this especially dangerous.
+S.scala:3: warning: adaptation of an empty argument list by appending () is deprecated: leaky (Object-receiving) target makes this especially dangerous
         signature: J(x: Any): J
   given arguments: <none>
  after adaptation: new J((): Unit)
@@ -28,13 +28,13 @@ S.scala:7: warning: adapted the argument list to the expected 3-tuple: add addit
  after adaptation: new Some((1, 2, 3): (Int, Int, Int))
   val y2 = new Some(1, 2, 3)
            ^
-S.scala:9: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+S.scala:9: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
         signature: J2(x: T): J2[T]
   given arguments: <none>
  after adaptation: new J2((): Unit)
   val z1 = new J2
            ^
-S.scala:10: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+S.scala:10: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
         signature: J2(x: T): J2[T]
   given arguments: <none>
  after adaptation: new J2((): Unit)

test/files/neg/t8035-deprecated.check

@@ -1,16 +1,28 @@
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 t8035-deprecated.scala:4: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+=======
+t8035-deprecated.scala:2: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: SetOps.apply(elem: A): Boolean
   given arguments: <none>
  after adaptation: SetOps((): Unit)
   List(1,2,3).toSet()
                    ^
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 t8035-deprecated.scala:7: warning: Adaptation of argument list by inserting () is deprecated: this is unlikely to be what you want.
+=======
+t8035-deprecated.scala:5: warning: adaptation of an empty argument list by appending () is deprecated: this is unlikely to be what you want
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: A(x: T): Foo.A[T]
   given arguments: <none>
  after adaptation: new A((): Unit)
   new A
   ^
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 t8035-deprecated.scala:11: warning: Adaptation of argument list by inserting () is deprecated: leaky (Object-receiving) target makes this especially dangerous.
+=======
+t8035-deprecated.scala:9: warning: adaptation of an empty argument list by appending () is deprecated: leaky (Object-receiving) target makes this especially dangerous
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: Format.format(x$1: Any): String
   given arguments: <none>
  after adaptation: Format.format((): Unit)

test/files/neg/t8035-removed.check

@@ -1,14 +1,26 @@
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 t8035-removed.scala:4: error: Adaptation of argument list by inserting () has been removed.
+=======
+t8035-removed.scala:4: error: adaptation of an empty argument list by appending () is unsupported
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: SetOps.apply(elem: A): Boolean
   given arguments: <none>
   List(1,2,3).toSet()
                    ^
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 t8035-removed.scala:7: error: Adaptation of argument list by inserting () has been removed.
+=======
+t8035-removed.scala:7: error: adaptation of an empty argument list by appending () is unsupported
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: A(x: T): Foo.A[T]
   given arguments: <none>
   new A
   ^
+<<<<<<< b357b3a7376da5eacdd23ed0ca14ae107028618e
 t8035-removed.scala:11: error: Adaptation of argument list by inserting () has been removed.
+=======
+t8035-removed.scala:11: error: adaptation of an empty argument list by appending () is unsupported
+>>>>>>> Remove adaptation of 0-arg methods under -Xsource:3.0
         signature: Format.format(x$1: Any): String
   given arguments: <none>
   sdf.format()

test/files/neg/t8035-removed.scala

@@ -1,4 +1,4 @@
-// scalac: -Xfuture
+// scalac:-Xsource:3.0
 //
 object Foo {
   List(1,2,3).toSet()

test/files/pos/t5413.scala

@@ -1,9 +1,11 @@
+/* scalac: -Xsource:3.0 */
+
 object Fail {
   def nom (guard : => Boolean) (something : => Unit): Unit = { }
   def main(args: Array[String]): Unit = {
     nom {
       val i = 0
       (i != 3)
-    }()
+    }(())
   }
 }

test/files/run/macro-range.flags

@@ -1 +1 @@
--language:experimental.macros
+-language:experimental.macros -Xsource:3.0

test/files/run/macro-range/Common_1.scala

@@ -40,7 +40,7 @@ abstract class Utils {
   }
   def makeWhile(lname: TermName, cond: Tree, body: Tree): Tree = {
     val continu = Apply(Ident(lname), Nil)
-    val rhs = If(cond, Block(List(body), continu), Literal(Constant()))
+    val rhs = If(cond, Block(List(body), continu), Literal(Constant(())))
     LabelDef(lname, Nil, rhs)
   }
   def makeBinop(left: Tree, op: String, right: Tree): Tree =

test/files/run/t576.check

@@ -1,4 +1,3 @@
-warning: there was one deprecation warning (since 2.11.0); re-run with -deprecation for details
 1
 2
 3

test/files/run/t576.scala

@@ -1,3 +1,5 @@
+/* -Xsource:3.0 */
+
 import scala.language.reflectiveCalls
 
 class A {
@@ -35,7 +37,10 @@ object Test {
 
     assert(x1 == x1)
     assert(x1 != x2)
-    assert(x1 != ())
+
+    // This is a workaround for x1 != (())
+    val unit = ()
+    assert(x1 != unit)
     assert(x2 != x1)
 
     assert(x3 == x3)

test/files/run/t6863.check

@@ -1,13 +1,12 @@
-t6863.scala:38: warning: comparing values of types Unit and Unit using `==' will always yield true
-    assert({ () => x}.apply == ())
+t6863.scala:43: warning: comparing values of types Unit and Unit using `==' will always yield true
+    assert({ () => x}.apply == u)
                             ^
-t6863.scala:42: warning: comparing values of types Unit and Unit using `==' will always yield true
-    assert({ () => x}.apply == ())
+t6863.scala:47: warning: comparing values of types Unit and Unit using `==' will always yield true
+    assert({ () => x}.apply == u)
                             ^
-t6863.scala:46: warning: comparing values of types Unit and Unit using `==' will always yield true
-    assert({ () => x}.apply == ())
+t6863.scala:51: warning: comparing values of types Unit and Unit using `==' will always yield true
+    assert({ () => x}.apply == u)
                             ^
-t6863.scala:59: warning: comparing values of types Unit and Unit using `==' will always yield true
-    assert({ () => x }.apply == ())
+t6863.scala:64: warning: comparing values of types Unit and Unit using `==' will always yield true
+    assert({ () => x }.apply == u)
                              ^
-warning: there were four deprecation warnings (since 2.11.0); re-run with -deprecation for details

test/files/run/t6863.scala

@@ -1,5 +1,10 @@
+/* scalac: -Xsource:3.0 */
+
 /** Make sure that when a variable is captured its initialization expression is handled properly */
 object Test {
+  // This is a workaround for x == (())
+  val u = ()
+
   def lazyVal() = {
   	// internally lazy vals become vars which are initialized with "_", so they need to be tested just like vars do
   	lazy val x = "42"
@@ -35,15 +40,15 @@ object Test {
   def assign() = {
     var y = 1
     var x = y = 42
-    assert({ () => x}.apply == ())
+    assert({ () => x}.apply == u)
   }
   def valDef() = {
     var x = {val y = 42}
-    assert({ () => x}.apply == ())
+    assert({ () => x}.apply == u)
   }
   def `return`(): String = {
     var x = if (true) return "42" else ()
-    assert({ () => x}.apply == ())
+    assert({ () => x}.apply == u)
     "42"
   }
   def tryFinally() = {
@@ -56,7 +61,7 @@ object Test {
   }
   def `if`() = {
   	var x = if (true) ()
-    assert({ () => x }.apply == ())
+    assert({ () => x }.apply == u)
   }
   def ifElse() = {
     var x = if(true) "42" else "43"

test/files/run/t6935.check

@@ -1 +0,0 @@
-warning: there was one deprecation warning (since 2.11.0); re-run with -deprecation for details

test/files/run/t6935.scala

@@ -1,3 +1,5 @@
+/* scalac: -Xsource:3.0 */
+
 object Test {
 
   def main(args: Array[String]): Unit = {
@@ -8,7 +10,9 @@ object Test {
     out.close()
     val buf = bytes.toByteArray
     val in = new ObjectInputStream(new ByteArrayInputStream(buf))
-    val unit = in.readObject()
-    assert(unit == ())
+    val actual = in.readObject()
+    // This is a workaround for actual == (())
+    val unit = ()
+    assert(actual == unit)
   }
 }

test/junit/scala/lang/stringinterpol/StringContextTest.scala

@@ -72,7 +72,7 @@ class StringContextTest {
 
   // verifying that the standard interpolators can be supplanted
   @Test def antiHijack_?() = {
-    object AllYourStringsAreBelongToMe { case class StringContext(args: Any*) { def s(args: Any) = "!!!!" } }
+    object AllYourStringsAreBelongToMe { case class StringContext(args: Any*) { def s(args: Any*) = "!!!!" } }
     import AllYourStringsAreBelongToMe._
     //assertEquals("????", s"????")
     assertEquals("!!!!", s"????") // OK to hijack core interpolator ids