Fix HK quoted pattern type variables (#16907)

The issue was in the encoding into
`{ExprMatchModule,TypeMatchModule}.unapply`. Specifically with the
`TypeBindings` argument. This arguments holds the list of type variable
definitions (`tpd.Bind` trees). We used a `Tuple` to list all the types
inside. The problem is that higher-kinded type variables do not conform
with the upper bounds of the tuple elements. The solution is to use an
HList with any-kinded elements.

Author: nicolasstucki

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -1508,7 +1508,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
     }
   }
 
-  /** Creates the tuple type tree repesentation of the type trees in `ts` */
+  /** Creates the tuple type tree representation of the type trees in `ts` */
   def tupleTypeTree(elems: List[Tree])(using Context): Tree = {
     val arity = elems.length
     if arity <= Definitions.MaxTupleArity then
@@ -1519,10 +1519,14 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
     else nestedPairsTypeTree(elems)
   }
 
-  /** Creates the nested pairs type tree repesentation of the type trees in `ts` */
+  /** Creates the nested pairs type tree representation of the type trees in `ts` */
   def nestedPairsTypeTree(ts: List[Tree])(using Context): Tree =
     ts.foldRight[Tree](TypeTree(defn.EmptyTupleModule.termRef))((x, acc) => AppliedTypeTree(TypeTree(defn.PairClass.typeRef), x :: acc :: Nil))
 
+  /** Creates the nested higher-kinded pairs type tree representation of the type trees in `ts` */
+  def hkNestedPairsTypeTree(ts: List[Tree])(using Context): Tree =
+    ts.foldRight[Tree](TypeTree(defn.QuoteMatching_KNil.typeRef))((x, acc) => AppliedTypeTree(TypeTree(defn.QuoteMatching_KCons.typeRef), x :: acc :: Nil))
+
   /** Replaces all positions in `tree` with zero-extent positions */
   private def focusPositions(tree: Tree)(using Context): Tree = {
     val transformer = new tpd.TreeMap {

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

@@ -865,6 +865,9 @@ class Definitions {
     @tu lazy val QuoteMatching_ExprMatchModule: Symbol = QuoteMatchingClass.requiredClass("ExprMatchModule")
     @tu lazy val QuoteMatching_TypeMatch: Symbol = QuoteMatchingClass.requiredMethod("TypeMatch")
     @tu lazy val QuoteMatching_TypeMatchModule: Symbol = QuoteMatchingClass.requiredClass("TypeMatchModule")
+  @tu lazy val QuoteMatchingModule: Symbol = requiredModule("scala.quoted.runtime.QuoteMatching")
+    @tu lazy val QuoteMatching_KNil: Symbol = QuoteMatchingModule.requiredType("KNil")
+    @tu lazy val QuoteMatching_KCons: Symbol = QuoteMatchingModule.requiredType("KCons")
 
   @tu lazy val ToExprModule: Symbol = requiredModule("scala.quoted.ToExpr")
     @tu lazy val ToExprModule_BooleanToExpr: Symbol = ToExprModule.requiredMethod("BooleanToExpr")

compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala

@@ -364,7 +364,7 @@ trait QuotesAndSplices {
    *
    *  ```
    *  case scala.internal.quoted.Expr.unapply[
-   *          Tuple1[t @ _], // Type binging definition
+   *          KList[t @ _, KNil], // Type binging definition
    *          Tuple2[Type[t], Expr[List[t]]] // Typing the result of the pattern match
    *        ](
    *          Tuple2.unapply
@@ -411,7 +411,7 @@ trait QuotesAndSplices {
     val replaceBindings = new ReplaceBindings
     val patType = defn.tupleType(splices.tpes.map(tpe => replaceBindings(tpe.widen)))
 
-    val typeBindingsTuple = tpd.tupleTypeTree(typeBindings.values.toList)
+    val typeBindingsTuple = tpd.hkNestedPairsTypeTree(typeBindings.values.toList)
 
     val replaceBindingsInTree = new TreeMap {
       private var bindMap = Map.empty[Symbol, Symbol]

compiler/src/scala/quoted/runtime/impl/QuoteMatcher.scala

@@ -121,9 +121,9 @@ object QuoteMatcher {
 
   private def withEnv[T](env: Env)(body: Env ?=> T): T = body(using env)
 
-  def treeMatch(scrutineeTerm: Tree, patternTerm: Tree)(using Context): Option[Tuple] =
+  def treeMatch(scrutineeTree: Tree, patternTree: Tree)(using Context): Option[Tuple] =
     given Env = Map.empty
-    scrutineeTerm =?= patternTerm
+    scrutineeTree =?= patternTree
 
   /** Check that all trees match with `mtch` and concatenate the results with &&& */
   private def matchLists[T](l1: List[T], l2: List[T])(mtch: (T, T) => Matching): Matching = (l1, l2) match {

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -3097,14 +3097,14 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
     new TypeImpl(tree, SpliceScope.getCurrent).asInstanceOf[scala.quoted.Type[T]]
 
   object ExprMatch extends ExprMatchModule:
-    def unapply[TypeBindings <: Tuple, Tup <: Tuple](scrutinee: scala.quoted.Expr[Any])(using pattern: scala.quoted.Expr[Any]): Option[Tup] =
+    def unapply[TypeBindings, Tup <: Tuple](scrutinee: scala.quoted.Expr[Any])(using pattern: scala.quoted.Expr[Any]): Option[Tup] =
       val scrutineeTree = reflect.asTerm(scrutinee)
       val patternTree = reflect.asTerm(pattern)
       treeMatch(scrutineeTree, patternTree).asInstanceOf[Option[Tup]]
   end ExprMatch
 
   object TypeMatch extends TypeMatchModule:
-    def unapply[TypeBindings <: Tuple, Tup <: Tuple](scrutinee: scala.quoted.Type[?])(using pattern: scala.quoted.Type[?]): Option[Tup] =
+    def unapply[TypeBindings, Tup <: Tuple](scrutinee: scala.quoted.Type[?])(using pattern: scala.quoted.Type[?]): Option[Tup] =
       val scrutineeTree = reflect.TypeTree.of(using scrutinee)
       val patternTree = reflect.TypeTree.of(using pattern)
       treeMatch(scrutineeTree, patternTree).asInstanceOf[Option[Tup]]

library/src/scala/quoted/runtime/QuoteMatching.scala

@@ -17,7 +17,7 @@ trait QuoteMatching:
     *    - `ExprMatch.unapply('{ f(0, myInt) })('{ f(patternHole[Int], patternHole[Int]) }, _)`
     *       will return `Some(Tuple2('{0}, '{ myInt }))`
     *    - `ExprMatch.unapply('{ f(0, "abc") })('{ f(0, patternHole[Int]) }, _)`
-    *       will return `None` due to the missmatch of types in the hole
+    *       will return `None` due to the mismatch of types in the hole
     *
     *  Holes:
     *    - scala.quoted.runtime.Patterns.patternHole[T]: hole that matches an expression `x` of type `Expr[U]`
@@ -27,7 +27,7 @@ trait QuoteMatching:
     *  @param pattern `Expr[Any]` containing the pattern tree
     *  @return None if it did not match, `Some(tup)` if it matched where `tup` contains `Expr[Ti]``
     */
-    def unapply[TypeBindings <: Tuple, Tup <: Tuple](scrutinee: Expr[Any])(using pattern: Expr[Any]): Option[Tup]
+    def unapply[TypeBindings, Tup <: Tuple](scrutinee: Expr[Any])(using pattern: Expr[Any]): Option[Tup]
   }
 
   val TypeMatch: TypeMatchModule
@@ -40,5 +40,10 @@ trait QuoteMatching:
      *  @param pattern `Type[?]` containing the pattern tree
      *  @return None if it did not match, `Some(tup)` if it matched where `tup` contains `Type[Ti]``
      */
-    def unapply[TypeBindings <: Tuple, Tup <: Tuple](scrutinee: Type[?])(using pattern: Type[?]): Option[Tup]
+    def unapply[TypeBindings, Tup <: Tuple](scrutinee: Type[?])(using pattern: Type[?]): Option[Tup]
   }
+
+object QuoteMatching:
+  type KList
+  type KCons[+H <: AnyKind, +T <: KList] <: KList
+  type KNil <: KList

project/MiMaFilters.scala

@@ -16,6 +16,7 @@ object MiMaFilters {
     ProblemFilters.exclude[MissingClassProblem]("scala.util.boundary$"),
     ProblemFilters.exclude[MissingClassProblem]("scala.util.boundary$Break"),
     ProblemFilters.exclude[MissingClassProblem]("scala.util.boundary$Label"),
+    ProblemFilters.exclude[MissingClassProblem]("scala.quoted.runtime.QuoteMatching$"),
 
     // Scala.js only: new runtime support class in 3.2.3; not available to users
     ProblemFilters.exclude[MissingClassProblem]("scala.scalajs.runtime.AnonFunctionXXL"),

tests/pos-macros/hk-quoted-type-patterns/Macro_1.scala

@@ -0,0 +1,17 @@
+import scala.quoted._
+
+private def impl(x: Expr[Any])(using Quotes): Expr[Unit] = {
+  x match
+    case '{ foo[x] } =>
+      assert(Type.show[x] == "scala.Int", Type.show[x])
+    case '{ type f[X]; foo[`f`] } =>
+      assert(Type.show[f] == "[A >: scala.Nothing <: scala.Any] => scala.collection.immutable.List[A]", Type.show[f])
+    case '{ type f <: AnyKind; foo[`f`] } =>
+      assert(Type.show[f] == "[K >: scala.Nothing <: scala.Any, V >: scala.Nothing <: scala.Any] => scala.collection.immutable.Map[K, V]", Type.show[f])
+    case x => throw MatchError(x.show)
+  '{}
+}
+
+inline def test(inline x: Any): Unit = ${ impl('x) }
+
+def foo[T <: AnyKind]: Any = ???

tests/pos-macros/hk-quoted-type-patterns/Test_2.scala

@@ -0,0 +1,5 @@
+@main
+def Test =
+  test(foo[Int])
+  test(foo[List])
+  test(foo[Map])