correctly type Expr.ofTupleFromSeq for arity > 22

Author: bishabosha

library/src/scala/quoted/Expr.scala

@@ -103,7 +103,7 @@ object Expr {
       case 20 => ofTupleFromSeq20(seq)
       case 21 => ofTupleFromSeq21(seq)
       case 22 => ofTupleFromSeq22(seq)
-      case _ => '{ Tuple.fromIArray(IArray(${Varargs(seq)}: _*)) }
+      case _ => ofTupleFromSeqXXL(seq)
     }
   }
 
@@ -214,6 +214,19 @@ object Expr {
       case Seq('{ $x1: t1 }, '{ $x2: t2 }, '{ $x3: t3 }, '{ $x4: t4 }, '{ $x5: t5 }, '{ $x6: t6 }, '{ $x7: t7 }, '{ $x8: t8 }, '{ $x9: t9 }, '{ $x10: t10 }, '{ $x11: t11 }, '{ $x12: t12 }, '{ $x13: t13 }, '{ $x14: t14 }, '{ $x15: t15 }, '{ $x16: t16 }, '{ $x17: t17 }, '{ $x18: t18 }, '{ $x19: t19 }, '{ $x20: t20 }, '{ $x21: t21 }, '{ $x22: t22 }) =>
         '{ Tuple22($x1, $x2, $x3, $x4, $x5, $x6, $x7, $x8, $x9, $x10, $x11, $x12, $x13, $x14, $x15, $x16, $x17, $x18, $x19, $x20, $x21, $x22) }
 
+  private def ofTupleFromSeqXXL(seq: Seq[Expr[Any]])(using Quotes): Expr[Tuple] =
+    val tupleTpe = tupleTypeFromSeq(seq)
+    tupleTpe.asType match
+      case '[tpe] =>
+        '{ Tuple.fromIArray(IArray(${Varargs(seq)}: _*)).asInstanceOf[tpe & Tuple] }
+
+  private def tupleTypeFromSeq(seq: Seq[Expr[Any]])(using Quotes): quotes.reflect.TypeRepr =
+    import quotes.reflect.*
+    val consRef = Symbol.classSymbol("scala.*:").typeRef
+    seq.foldLeft(TypeRepr.of[EmptyTuple]) { (ts, expr) =>
+      expr match
+        case '{ $e: t } => AppliedType(consRef, TypeRepr.of[t] :: ts :: Nil)
+    }
 
   /** Given a tuple of the form `(Expr[A1], ..., Expr[An])`, outputs a tuple `Expr[(A1, ..., An)]`. */
   def ofTuple[T <: Tuple: Tuple.IsMappedBy[Expr]: Type](tup: T)(using Quotes): Expr[Tuple.InverseMap[T, Expr]] = {

tests/run-macros/i17257/a.scala

@@ -0,0 +1,38 @@
+package derivation
+import scala.quoted.*
+
+import scala.annotation.tailrec
+
+object Helpers:
+
+  // file a.scala
+  inline def summonAllOptimized[T <: Tuple]: T =
+    ${ summonAllOptimizedImpl[T] }
+
+  private def summonAllOptimizedImpl[T <: Tuple: Type](using q: Quotes): Expr[T] = {
+    import q.reflect.*
+
+    Expr
+      .ofTupleFromSeq(typesOfTuple(TypeRepr.of[T], Nil).map { tpe =>
+        tpe.asType match {
+          case '[t] =>
+            Expr.summon[t].getOrElse(report.errorAndAbort(s"Unable to to find implicit instance for ${tpe.show}"))
+        }
+      })
+      .asExprOf[T]
+  }
+
+  @tailrec
+  private[derivation] def typesOfTuple(
+      using q: Quotes
+  )(tpe: q.reflect.TypeRepr, acc: List[q.reflect.TypeRepr]): List[q.reflect.TypeRepr] =
+    import q.reflect.*
+    val cons = Symbol.classSymbol("scala.*:")
+    tpe.widenTermRefByName.dealias match
+      case AppliedType(fn, tpes) if defn.isTupleClass(fn.typeSymbol) =>
+        tpes.reverse_:::(acc)
+      case AppliedType(tp, List(headType, tailType)) if tp.derivesFrom(cons) =>
+        typesOfTuple(tailType, headType :: acc)
+      case tpe =>
+        if tpe.derivesFrom(Symbol.classSymbol("scala.EmptyTuple")) then acc.reverse
+        else report.errorAndAbort(s"Unknown type encountered in tuple ${tpe.show}")

tests/run-macros/i17257/b.scala

@@ -0,0 +1,21 @@
+package derivation {
+  //file b.scala
+  val test = Helpers.summonAllOptimized[(
+      ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"],
+      ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"],
+      ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"],
+      ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"], ValueOf["a"],
+      ValueOf["a"], ValueOf["a"], ValueOf["a"] //Commenting out the last one here fixes the compile error
+    )]
+}
+@main def Test =
+  def assertions(list: List[ValueOf["a"]]): Unit =
+    assert(list.size == 23)
+    assert(list.map(_.value) == List(
+      "a", "a", "a", "a", "a",
+      "a", "a", "a", "a", "a",
+      "a", "a", "a", "a", "a",
+      "a", "a", "a", "a", "a",
+      "a", "a", "a"
+    ))
+  assertions(derivation.test.toList)