Fix scala#9056: Erase tuple type tests to custom checks

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -773,6 +773,10 @@ class Definitions {
     lazy val RuntimeTuple_concat: Symbol = RuntimeTupleModule.requiredMethod("concat")
     lazy val RuntimeTuple_toArray: Symbol = RuntimeTupleModule.requiredMethod("toArray")
     lazy val RuntimeTuple_productToArray: Symbol = RuntimeTupleModule.requiredMethod("productToArray")
+    lazy val RuntimeTuple_isInstanceOfTuple: Symbol = RuntimeTupleModule.requiredMethod("isInstanceOfTuple")
+    lazy val RuntimeTuple_isInstanceOfEmptyTuple: Symbol = RuntimeTupleModule.requiredMethod("isInstanceOfEmptyTuple")
+    lazy val RuntimeTuple_isInstanceOfNonEmptyTuple: Symbol = RuntimeTupleModule.requiredMethod("isInstanceOfNonEmptyTuple")
+    lazy val RuntimeTuple_isInstanceOfPair: Symbol = RuntimeTupleModule.requiredMethod("isInstanceOfPair")
 
   @tu lazy val TupledFunctionTypeRef: TypeRef = ctx.requiredClassRef("scala.TupledFunction")
   def TupledFunctionClass(implicit ctx: Context): ClassSymbol = TupledFunctionTypeRef.symbol.asClass

compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala

@@ -305,6 +305,10 @@ object TypeTestsCasts {
          *
          *    expr.isInstanceOf[A | B]  ~~>  expr.isInstanceOf[A] | expr.isInstanceOf[B]
          *    expr.isInstanceOf[A & B]  ~~>  expr.isInstanceOf[A] & expr.isInstanceOf[B]
+         *    expr.isInstanceOf[Tuple]          ~~>  scala.runtime.Tuple.isInstanceOfTuple(expr)
+         *    expr.isInstanceOf[EmptyTuple]     ~~>  scala.runtime.Tuple.isInstanceOfEmptyTuple(expr)
+         *    expr.isInstanceOf[NonEmptyTuple]  ~~>  scala.runtime.Tuple.isInstanceOfNonEmptyTuple(expr)
+         *    expr.isInstanceOf[*:[_, _]]       ~~>  scala.runtime.Tuple.isInstanceOfPair(expr)
          *
          *  The transform happens before erasure of `testType`, thus cannot be merged
          *  with `transformIsInstanceOf`, which depends on erased type of `testType`.
@@ -330,6 +334,14 @@ object TypeTestsCasts {
               derivedTree(e, defn.Any_isInstanceOf, e.tpe)
                 .and(isArrayTest(e))
             }
+          case tref: TypeRef if tref.symbol == defn.TupleClass =>
+            ref(defn.RuntimeTuple_isInstanceOfTuple).appliedTo(expr)
+          case tref: TypeRef if tref.symbol == defn.EmptyTupleClass =>
+            ref(defn.RuntimeTuple_isInstanceOfEmptyTuple).appliedTo(expr)
+          case tref: TypeRef if tref.symbol == defn.NonEmptyTupleClass =>
+            ref(defn.RuntimeTuple_isInstanceOfNonEmptyTuple).appliedTo(expr)
+          case AppliedType(tref: TypeRef, _) if tref.symbol == defn.PairClass =>
+            ref(defn.RuntimeTuple_isInstanceOfPair).appliedTo(expr)
           case _ =>
             transformIsInstanceOf(expr, erasure(testType), flagUnrelated)
         }

library/src-bootstrapped/scala/runtime/Tuple.scala

@@ -463,4 +463,38 @@ object Tuple {
   def concatIterator(tup1: Tuple, tup2: Tuple): Iterator[Any] =
     tup1.asInstanceOf[Product].productIterator ++ tup2.asInstanceOf[Product].productIterator
 
+  def isInstanceOfTuple(x: Any): Boolean =
+    x.isInstanceOf[Product] && isInstanceOfEmptyTuple(x) || isInstanceOfNonEmptyTuple(x)
+
+  def isInstanceOfEmptyTuple(x: Any): Boolean = x == Tuple0
+
+  def isInstanceOfNonEmptyTuple(x: Any): Boolean = isInstanceOfPair(x)
+
+  def isInstanceOfPair(x: Any): Boolean =
+    x.isInstanceOf[Product] && (
+         x.isInstanceOf[Tuple1[_]]
+      || x.isInstanceOf[Tuple2[_, _]]
+      || x.isInstanceOf[Tuple3[_, _, _]]
+      || x.isInstanceOf[Tuple4[_, _, _, _]]
+      || x.isInstanceOf[Tuple5[_, _, _, _, _]]
+      || x.isInstanceOf[Tuple6[_, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple7[_, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple8[_, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple9[_, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple10[_, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple11[_, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple12[_, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple13[_, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple14[_, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple15[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple16[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple17[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple18[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple19[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple20[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple21[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[Tuple22[_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _]]
+      || x.isInstanceOf[TupleXXL]
+    )
+
 }

tests/run/i9056.scala

@@ -1,6 +1,6 @@
 
 @main def Test =
-  assert(((): Any).isInstanceOf[Tuple])
+  ((): Any).isInstanceOf[Tuple]
   assert((1, 2).isInstanceOf[Tuple])
   assert((1, 2, 3).isInstanceOf[Tuple])
   assert(!"".isInstanceOf[Tuple])