Fix #9518: Instantiate HKTypeLambda in AppliedTypes

Author: nicolasstucki

compiler/src/dotty/tools/dotc/quoted/reflect/ReflectionCompilerInterface.scala

@@ -1335,7 +1335,10 @@ class ReflectionCompilerInterface(val rootContext: Context) extends CompilerInte
   def AppliedType_tycon(self: AppliedType)(using Context): Type = self.tycon
   def AppliedType_args(self: AppliedType)(using Context): List[TypeOrBounds] = self.args
 
-  def AppliedType_apply(tycon: Type, args: List[TypeOrBounds])(using Context): AppliedType = Types.AppliedType(tycon, args)
+  def AppliedType_apply(tycon: Type, args: List[TypeOrBounds])(using Context): Type =
+    tycon match
+      case tycon: Types.HKTypeLambda => tycon.instantiate(args)
+      case _ => Types.AppliedType(tycon, args)
 
   type AnnotatedType = Types.AnnotatedType
 

library/src/scala/internal/tasty/CompilerInterface.scala

@@ -644,7 +644,7 @@ trait CompilerInterface extends scala.tasty.reflect.Types {
   def AppliedType_tycon(self: AppliedType)(using ctx: Context): Type
   def AppliedType_args(self: AppliedType)(using ctx: Context): List[TypeOrBounds]
 
-  def AppliedType_apply(tycon: Type, args: List[TypeOrBounds])(using ctx: Context) : AppliedType
+  def AppliedType_apply(tycon: Type, args: List[TypeOrBounds])(using ctx: Context) : Type
 
   def AnnotatedType_TypeTest(using ctx: Context): TypeTest[TypeOrBounds, AnnotatedType]
 

library/src/scala/tasty/Reflection.scala

@@ -1549,7 +1549,7 @@ trait Reflection extends reflect.Types { reflectSelf: CompilerInterface =>
   given AppliedTypeOps as AppliedType.type = AppliedType
 
   object AppliedType:
-    def apply(tycon: Type, args: List[TypeOrBounds])(using ctx: Context): AppliedType =
+    def apply(tycon: Type, args: List[TypeOrBounds])(using ctx: Context): Type =
       reflectSelf.AppliedType_apply(tycon, args)
     def unapply(x: AppliedType)(using ctx: Context): Option[(Type, List[TypeOrBounds /* Type | TypeBounds */])] =
       Some((x.tycon, x.args))

tests/pos-macros/i9518/Macro_1.scala

@@ -0,0 +1,21 @@
+
+import scala.quoted._
+
+trait CB[T]
+
+inline def shift : Unit = ${ shiftTerm }
+
+def shiftTerm(using QuoteContext): Expr[Unit] = {
+  import qctx.tasty._
+  val nTree = '{ ??? : CB[Int] }.unseal
+  val tp1 = '[CB[Int]].unseal.tpe
+  val tp2 = '[([X] =>> CB[X])[Int]].unseal.tpe
+  val ta = '[[X] =>> CB[X]]
+  val tp3 = '[ta.T[Int]].unseal.tpe
+  val tp4 = AppliedType('[CB].unseal.tpe, List(typeOf[Int]))
+  assert(nTree.tpe <:< tp1)
+  assert(nTree.tpe <:< tp2)
+  assert(nTree.tpe <:< tp3)
+  assert(nTree.tpe <:< tp4)
+  '{}
+}

tests/pos-macros/i9518/Test_2.scala

@@ -0,0 +1 @@
+def test: Unit = shift