Add toExprOfTuple method for tuples

Author: anatoliykmetyuk

compiler/test/dotc/pos-test-pickling.blacklist

@@ -24,3 +24,6 @@ matchtype.scala
 
 # Opaque type
 i5720.scala
+
+# Tuples
+toexproftuple.scala

library/src-bootstrapped/scala/quoted/package.scala

@@ -97,4 +97,10 @@ package object quoted {
     }
   }
 
+  def (tup: T) toExprOfTuple[T <: Tuple: Tuple.IsInverseMap[Expr]] given (
+    ctx: QuoteContext, t: Type[Tuple.InverseMap[T, Expr]]): Expr[Tuple.InverseMap[T, Expr]] = {
+    import ctx.tasty._
+    val res: Expr[Tuple] = tup.asInstanceOf[Product].productIterator.toSeq.asInstanceOf[Seq[Expr[_]]].toExprOfTuple
+    res.cast[Tuple.InverseMap[T, Expr]]
+  }
 }

library/src/scala/Tuple.scala

@@ -1,5 +1,5 @@
 package scala
-import annotation.showAsInfix
+import annotation.{ showAsInfix, implicitNotFound }
 import compiletime._
 import internal._
 
@@ -74,6 +74,27 @@ object Tuple {
     case h *: t => F[h] *: Map[t, F]
   }
 
+  /** Converts a tuple `(F[T1], ..., F[Tn])` to `(T1,  ... Tn)` */
+  type InverseMap[X <: Tuple, F[_]] <: Tuple = X match {
+    case F[x] *: t => x *: InverseMap[t, F]
+    case Unit => Unit
+  }
+  type IsInverseMap[F[_]] = [X <: Tuple] =>> Tuple.IsInverseMap.PredicateAux[X, F, InverseMap[X, F]]
+  object IsInverseMap {
+    sealed trait Predicate[X <: Tuple, F[_]] { type Result <: Tuple }
+    type PredicateAux[X <: Tuple, F[_], R] = Predicate[X, F] { type Result = R }
+
+    given [X <: NonEmptyTuple, F[_], H, T <: Tuple] as PredicateAux[X, F, H *: T] given (
+      e1: Head[X] =:= F[H],
+      e2: PredicateAux[Tail[X], F, T]) = new Predicate[X, F] {
+      type Result = H *: T
+    }
+
+    given [F[_]] as PredicateAux[Unit, F, Unit] = new Predicate[Unit, F] {
+      type Result = Unit
+    }
+  }
+
   /** Convert an array into a tuple of unknown arity and types */
   def fromArray[T](xs: Array[T]): Tuple = {
     val xs2 = xs match {

tests/neg/toexproftuple.scala

@@ -0,0 +1,11 @@
+import scala.quoted._, scala.deriving._
+import given scala.quoted._
+
+inline def mcr: Any = ${mcrImpl}
+def mcrImpl given (ctx: QuoteContext): Expr[Any] = {
+  val tpl: (Expr[1], Expr[2], Expr[3]) = ('{1}, '{2}, '{3})
+  '{val res: (1, 3, 3) = ${tpl.toExprOfTuple}; res}  // error
+
+  val tpl2: (Expr[1], 2, Expr[3]) = ('{1}, 2, '{3})
+  '{val res = ${tpl2.toExprOfTuple}; res}  // error
+}

tests/pos/toexproftuple.scala

@@ -0,0 +1,8 @@
+import scala.quoted._, scala.deriving._
+import given scala.quoted._
+
+inline def mcr: Any = ${mcrImpl}
+def mcrImpl given (ctx: QuoteContext): Expr[Any] = {
+  val tpl: (Expr[1], Expr[2], Expr[3]) = ('{1}, '{2}, '{3})
+  '{val res: (1, 2, 3) = ${tpl.toExprOfTuple}; res}
+}