Merge pull request #14923 from dotty-staging/fix-14740

Add reflect AppliedType constructor

Author: nicolasstucki

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

@@ -1893,6 +1893,8 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
     end AppliedTypeTypeTest
 
     object AppliedType extends AppliedTypeModule:
+      def apply(tycon: TypeRepr, args: List[TypeRepr]): AppliedType =
+        Types.AppliedType(tycon, args)
       def unapply(x: AppliedType): (TypeRepr, List[TypeRepr]) =
         (AppliedTypeMethods.tycon(x), AppliedTypeMethods.args(x))
     end AppliedType

library/src/scala/quoted/Quotes.scala

@@ -2812,6 +2812,9 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
 
     /** Methods of the module object `val AppliedType` */
     trait AppliedTypeModule { this: AppliedType.type =>
+      /** Applied the type constructor `T` to a list of type arguments `T_1,..,T_n` to create `T[T_1,..,T_n]` */
+      @experimental
+      def apply(tycon: TypeRepr, args: List[TypeRepr]): AppliedType
       def unapply(x: AppliedType): (TypeRepr, List[TypeRepr])
     }
 

project/MiMaFilters.scala

@@ -11,6 +11,7 @@ object MiMaFilters {
     ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolMethods.typeRef"),
     ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolMethods.termRef"),
     ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#TypeTreeModule.ref"),
+    ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#AppliedTypeModule.apply"),
 
     // Experimental `MainAnnotation` APIs. Can be added in 3.3.0 or later.
     ProblemFilters.exclude[MissingClassProblem]("scala.annotation.MainAnnotation"),

tests/pos-macros/i14740/Macro_1.scala

@@ -0,0 +1,11 @@
+import scala.quoted.*
+
+type Foo[T]
+
+transparent inline def emptyList[T]: Any = ${ impl[T] }
+
+private def impl[T: Type](using Quotes): Expr[Any] = {
+  import quotes.reflect._
+  val tpe = AppliedType(TypeRepr.of[Foo], List(TypeRepr.of[T])) // test AppliedType constructor
+  Typed('{???}.asTerm, Inferred(tpe)).asExpr // '{ ??? : Foo[T] }
+}

tests/pos-macros/i14740/Test_2.scala

@@ -0,0 +1,3 @@
+def test1: Foo[Any] = emptyList[Any]
+def test2: Foo[Int] = emptyList[Int]
+def test3: Foo[String] = emptyList[String]