Add uniform Tuple.apply and Tuple.unapply

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -362,7 +362,10 @@ object SpaceEngine {
       val funRef = fun1.tpe.asInstanceOf[TermRef]
       if (fun.symbol.name == nme.unapplySeq)
         val (arity, elemTp, resultTp) = unapplySeqInfo(fun.tpe.widen.finalResultType, fun.srcPos)
-        if fun.symbol.owner == defn.SeqFactoryClass && toUnderlying(pat.tpe).dealias.derivesFrom(defn.ListClass) then
+        // Special case: Tuple.unapplySeq with empty patterns covers EmptyTuple
+        if pats.isEmpty && fun.symbol.owner == defn.TupleModule.moduleClass then
+          Typ(defn.EmptyTupleModule.termRef, decomposed = false)
+        else if fun.symbol.owner == defn.SeqFactoryClass && toUnderlying(pat.tpe).dealias.derivesFrom(defn.ListClass) then
           // The exhaustivity and reachability logic already handles decomposing sum types (into its subclasses)
           // and product types (into its components).  To get better counter-examples for patterns that are of type
           // List (or a super-type of list, like LinearSeq) we project them into spaces that use `::` and Nil.

library/src/scala/Tuple.scala

@@ -1,7 +1,7 @@
 package scala
 
 import language.experimental.captureChecking
-import annotation.showAsInfix
+import annotation.{showAsInfix, targetName}
 import compiletime.*
 import compiletime.ops.int.*
 
@@ -288,9 +288,114 @@ object Tuple {
   /** Tuple with one element. */
   def apply[T](x: T): T *: EmptyTuple = Tuple1(x)
 
+  /** Uniform tuple construction for any arity with type preservation.
+   *  For arities 0 and 1, the overloads above are preferred (binary compatibility).
+   *  For arities >= 2, this varargs version is used.
+   *
+   *  Examples:
+   *  {{{
+   *  Tuple()              // EmptyTuple
+   *  Tuple(1)             // Tuple1[Int]
+   *  Tuple(1, "a")        // (Int, String)
+   *  Tuple(1, "a", 2.0)   // (Int, String, Double)
+   *  }}}
+   */
+  transparent inline def apply(inline args: Any*): Tuple = ${ TupleMacros.applyImpl('args) }
+
   /** Matches an empty tuple. */
   def unapply(x: EmptyTuple): true = true
 
+  /** Matches a 1-tuple, extracting its element. */
+  @targetName("unapply1")
+  inline def unapply[A](x: Tuple1[A]): Some[A] = Some(x._1)
+
+  /** Matches a 2-tuple, extracting its elements. */
+  @targetName("unapply2")
+  inline def unapply[A, B](x: (A, B)): (A, B) = x
+
+  /** Matches a 3-tuple, extracting its elements. */
+  @targetName("unapply3")
+  inline def unapply[A, B, C](x: (A, B, C)): (A, B, C) = x
+
+  /** Matches a 4-tuple, extracting its elements. */
+  @targetName("unapply4")
+  inline def unapply[A, B, C, D](x: (A, B, C, D)): (A, B, C, D) = x
+
+  /** Matches a 5-tuple, extracting its elements. */
+  @targetName("unapply5")
+  inline def unapply[A, B, C, D, E](x: (A, B, C, D, E)): (A, B, C, D, E) = x
+
+  /** Matches a 6-tuple, extracting its elements. */
+  @targetName("unapply6")
+  inline def unapply[A, B, C, D, E, F](x: (A, B, C, D, E, F)): (A, B, C, D, E, F) = x
+
+  /** Matches a 7-tuple, extracting its elements. */
+  @targetName("unapply7")
+  inline def unapply[A, B, C, D, E, F, G](x: (A, B, C, D, E, F, G)): (A, B, C, D, E, F, G) = x
+
+  /** Matches a 8-tuple, extracting its elements. */
+  @targetName("unapply8")
+  inline def unapply[A, B, C, D, E, F, G, H](x: (A, B, C, D, E, F, G, H)): (A, B, C, D, E, F, G, H) = x
+
+  /** Matches a 9-tuple, extracting its elements. */
+  @targetName("unapply9")
+  inline def unapply[A, B, C, D, E, F, G, H, I](x: (A, B, C, D, E, F, G, H, I)): (A, B, C, D, E, F, G, H, I) = x
+
+  /** Matches a 10-tuple, extracting its elements. */
+  @targetName("unapply10")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J](x: (A, B, C, D, E, F, G, H, I, J)): (A, B, C, D, E, F, G, H, I, J) = x
+
+  /** Matches a 11-tuple, extracting its elements. */
+  @targetName("unapply11")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K](x: (A, B, C, D, E, F, G, H, I, J, K)): (A, B, C, D, E, F, G, H, I, J, K) = x
+
+  /** Matches a 12-tuple, extracting its elements. */
+  @targetName("unapply12")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L](x: (A, B, C, D, E, F, G, H, I, J, K, L)): (A, B, C, D, E, F, G, H, I, J, K, L) = x
+
+  /** Matches a 13-tuple, extracting its elements. */
+  @targetName("unapply13")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M](x: (A, B, C, D, E, F, G, H, I, J, K, L, M)): (A, B, C, D, E, F, G, H, I, J, K, L, M) = x
+
+  /** Matches a 14-tuple, extracting its elements. */
+  @targetName("unapply14")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N) = x
+
+  /** Matches a 15-tuple, extracting its elements. */
+  @targetName("unapply15")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O) = x
+
+  /** Matches a 16-tuple, extracting its elements. */
+  @targetName("unapply16")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P) = x
+
+  /** Matches a 17-tuple, extracting its elements. */
+  @targetName("unapply17")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q) = x
+
+  /** Matches a 18-tuple, extracting its elements. */
+  @targetName("unapply18")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R) = x
+
+  /** Matches a 19-tuple, extracting its elements. */
+  @targetName("unapply19")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S) = x
+
+  /** Matches a 20-tuple, extracting its elements. */
+  @targetName("unapply20")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T) = x
+
+  /** Matches a 21-tuple, extracting its elements. */
+  @targetName("unapply21")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U) = x
+
+  /** Matches a 22-tuple, extracting its elements. */
+  @targetName("unapply22")
+  inline def unapply[A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V](x: (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V)): (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V) = x
+
+  /** Fallback for abstract Tuple types - provides runtime arity matching. */
+  def unapplySeq(x: Tuple): Option[Seq[Any]] = Some(x.productIterator.toSeq)
+
   /** Converts an array into a tuple of unknown arity and types. */
   def fromArray[T](xs: Array[T]): Tuple = {
     val xs2 = xs match {

library/src/scala/TupleMacros.scala

@@ -0,0 +1,66 @@
+package scala
+
+import scala.quoted.*
+
+object TupleMacros {
+
+  /** Macro implementation for type-preserving Tuple construction.
+   *  Extracts the precise types of each argument and builds a properly typed TupleN.
+   */
+  def applyImpl(args: Expr[Seq[Any]])(using Quotes): Expr[Tuple] = {
+    import quotes.reflect.*
+
+    def extractRepeated(term: Term): List[Term] = term match {
+      case Repeated(elems, _) => elems
+      case Inlined(_, _, inner) => extractRepeated(inner)
+      case Typed(inner, _) => extractRepeated(inner)
+      case Block(_, inner) => extractRepeated(inner)
+      case _ =>
+        report.error(s"Expected literal varargs, got: ${term.show}")
+        Nil
+    }
+
+    val argTerms = extractRepeated(args.asTerm)
+    val n = argTerms.length
+
+    n match {
+      case 0 => '{ EmptyTuple }
+      case _ if n <= scala.runtime.Tuples.MaxSpecialized =>
+        val tupleClass = Symbol.requiredClass(s"scala.Tuple$n")
+        val tupleType = tupleClass.typeRef.appliedTo(argTerms.map(_.tpe.widen))
+        val tupleCompanion = tupleClass.companionModule
+
+        val applyMethod = tupleCompanion.methodMember("apply").head
+        val call = Apply(
+          TypeApply(
+            Select(Ref(tupleCompanion), applyMethod),
+            argTerms.map(t => TypeTree.of(using t.tpe.widen.asType.asInstanceOf[Type[Any]]))
+          ),
+          argTerms
+        )
+
+        tupleType.asType match {
+          case '[t] => call.asExprOf[t & Tuple]
+        }
+
+      case _ =>
+        val consType = argTerms.foldRight(TypeRepr.of[EmptyTuple]) { (term, acc) =>
+          TypeRepr.of[*:].appliedTo(List(term.tpe.widen, acc))
+        }
+
+        val arrayElements = argTerms.map { t =>
+          t.tpe.widen.asType match {
+            case '[elem] =>
+              val termExpr = t.asExprOf[elem]
+              '{ $termExpr.asInstanceOf[Object] }
+          }
+        }
+        val arrayExpr = Expr.ofSeq(arrayElements)
+
+        consType.asType match {
+          case '[t] =>
+            '{ scala.runtime.Tuples.fromArray($arrayExpr.toArray[Object]).asInstanceOf[t & Tuple] }
+        }
+    }
+  }
+}

project/MiMaFilters.scala

@@ -11,6 +11,10 @@ object MiMaFilters {
         ProblemFilters.exclude[DirectMissingMethodProblem]("scala.caps.package#package.freeze"),
         // scala/scala3#24545 / scala/scala3#24788
         ProblemFilters.exclude[MissingClassProblem]("scala.annotation.unchecked.uncheckedOverride"),
+        // scala/scala3#24874 - Uniform Tuple.apply and Tuple.unapply for SIP-NN
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.Tuple.unapply*"),
+        ProblemFilters.exclude[MissingClassProblem]("scala.TupleMacros"),
+        ProblemFilters.exclude[MissingClassProblem]("scala.TupleMacros$"),
       ),
 
     )

repl/src/dotty/tools/repl/Rendering.scala

@@ -98,13 +98,12 @@ private[repl] class Rendering(parentClassLoader: Option[ClassLoader] = None):
 
   /** Return a colored fansi.Str representation of a value we got from `classLoader()`. */
   private[repl] def replStringOf(value: Object, prefixLength: Int)(using Context): fansi.Str = {
-    // pretty-print things with 100 cols 50 rows by default,
-    val res = pprintRender(
-      value,
-      width = 100,
-      height = 50,
-      initialOffset = prefixLength
-    )
+    // Use Tuple1(x) format to avoid pprint's "(x,)" format
+    val res = value match {
+      case t: Tuple1[?] => s"Tuple1(${t._1})"
+      case _ =>
+        pprintRender(value, width = 100, height = 50, initialOffset = prefixLength)
+    }
     if (ctx.settings.color.value == "never") fansi.Str(res).plainText else res
   }
 

tests/run/tuple-apply-unapply.check

@@ -0,0 +1,18 @@
+=== Tuple.apply tests ===
+Tuple() = ()
+Tuple(42) = (42)
+Tuple(1, hello) = (1,hello)
+Tuple(1, a, 3.14) = (1,a,3.14)
+Tuple(1..22) arity = 22
+Tuple(1..23) arity = 23
+=== Type preservation tests ===
+Type preservation: OK
+=== Tuple.unapply tests ===
+EmptyTuple: OK
+Tuple1: 42 (typed Int)
+Tuple2: 1, hello (typed)
+Tuple3: 1, a, 3.14 (typed)
+=== Abstract Tuple (unapplySeq) ===
+Abstract 3-tuple: 1, hello, 3.14
+Correct arity matched
+=== All tests passed ===

tests/run/tuple-apply-unapply.scala

@@ -0,0 +1,93 @@
+/** Test for uniform Tuple.apply
+ *
+ *  Tuple.apply: uniform construction for any arity with type preservation
+ */
+object Test extends App {
+
+  // === APPLY TESTS ===
+  println("=== Tuple.apply tests ===")
+
+  // Arity 0
+  val t0 = Tuple()
+  assert(t0 == EmptyTuple)
+  println(s"Tuple() = $t0")
+
+  // Arity 1
+  val t1 = Tuple(42)
+  assert(t1 == Tuple1(42))
+  println(s"Tuple(42) = $t1")
+
+  // Arity 2
+  val t2 = Tuple(1, "hello")
+  assert(t2 == (1, "hello"))
+  println(s"Tuple(1, hello) = $t2")
+
+  // Arity 3
+  val t3 = Tuple(1, "a", 3.14)
+  assert(t3 == (1, "a", 3.14))
+  println(s"Tuple(1, a, 3.14) = $t3")
+
+  // Arity 22 (max specialized)
+  val t22 = Tuple(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
+  assert(t22.productArity == 22)
+  println(s"Tuple(1..22) arity = ${t22.productArity}")
+
+  // Arity 23 (TupleXXL)
+  val t23 = Tuple(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
+  assert(t23.productArity == 23)
+  println(s"Tuple(1..23) arity = ${t23.productArity}")
+
+  // === TYPE PRESERVATION TESTS ===
+  println("=== Type preservation tests ===")
+
+  // Verify types are preserved (these would fail to compile if types were wrong)
+  val check0: EmptyTuple = t0
+  val check1: Tuple1[Int] = t1
+  val check2: (Int, String) = t2
+  val check3: (Int, String, Double) = t3
+
+  println("Type preservation: OK")
+
+  // === UNAPPLY TESTS ===
+  println("=== Tuple.unapply tests ===")
+
+  // EmptyTuple
+  EmptyTuple match
+    case Tuple() => println("EmptyTuple: OK")
+
+  // Tuple1 - typed extraction
+  Tuple1(42) match
+    case Tuple(x) =>
+      val check: Int = x
+      println(s"Tuple1: $x (typed Int)")
+
+  // Tuple2 - typed extraction
+  (1, "hello") match
+    case Tuple(a, b) =>
+      val checkA: Int = a
+      val checkB: String = b
+      println(s"Tuple2: $a, $b (typed)")
+
+  // Tuple3 - typed extraction
+  (1, "a", 3.14) match
+    case Tuple(a, b, c) =>
+      val checkA: Int = a
+      val checkB: String = b
+      val checkC: Double = c
+      println(s"Tuple3: $a, $b, $c (typed)")
+
+  // Abstract Tuple - unapplySeq fallback (elements are Any)
+  println("=== Abstract Tuple (unapplySeq) ===")
+  val abstractTuple: Tuple = (1, "hello", 3.14)
+  abstractTuple match
+    case Tuple(a, b, c) => println(s"Abstract 3-tuple: $a, $b, $c")
+    case _ => assert(false, "Should have matched")
+
+  // Arity mismatch - should not match
+  abstractTuple match
+    case Tuple(a, b) => assert(false, "Should not match wrong arity")
+    case Tuple(a, b, c) => println("Correct arity matched")
+    case _ => assert(false, "Should have matched")
+
+  println("=== All tests passed ===")
+}