Fix #8520: Add Reflection.Symbol.typeMembers

Author: nicolasstucki

compiler/src/dotty/tools/dotc/tastyreflect/ReflectionCompilerInterface.scala

@@ -1732,6 +1732,12 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
       case sym if isMethod(sym) && sym.name.toString == name => sym.asTerm
     }.toList
 
+  def Symbol_typeMembers(self: Symbol)(using ctx: Context): List[Symbol] =
+    self.unforcedDecls.filter(_.isType)
+
+  def Symbol_typeMember(self: Symbol)(name: String)(using ctx: Context): Symbol =
+    self.unforcedDecls.find(sym => sym.name == name.toTypeName)
+
   def Symbol_classMethods(self: Symbol)(using ctx: Context): List[Symbol] =
     self.typeRef.decls.iterator.collect {
       case sym if isMethod(sym) => sym.asTerm

library/src/scala/tasty/Reflection.scala

@@ -2219,6 +2219,14 @@ class Reflection(private[scala] val internal: CompilerInterface) { self =>
     def classMethods(using ctx: Context): List[Symbol] =
       internal.Symbol_classMethods(sym)
 
+    /** Type member directly declared in the class */
+    def typeMembers(using ctx: Context): List[Symbol] =
+      internal.Symbol_typeMembers(sym)
+
+    /** Type member with the given name directly declared in the class */
+    def typeMember(name: String)(using ctx: Context): Symbol =
+      internal.Symbol_typeMember(sym)(name)
+
     /** Get named non-private methods declared or inherited */
     def method(name: String)(using ctx: Context): List[Symbol] =
       internal.Symbol_method(sym)(name)

library/src/scala/tasty/reflect/CompilerInterface.scala

@@ -1308,6 +1308,12 @@ trait CompilerInterface {
   /** Get all non-private methods declared or inherited */
   def Symbol_methods(self: Symbol)(using ctx: Context): List[Symbol]
 
+  /** Type member directly declared in the class */
+  def Symbol_typeMembers(self: Symbol)(using ctx: Context): List[Symbol]
+
+  /** Type member with the given name directly declared in the class */
+  def Symbol_typeMember(self: Symbol)(name: String)(using ctx: Context): Symbol
+
   /** The symbols of each type parameter list and value parameter list of this
    *  method, or Nil if this isn't a method.
    */

tests/run-macros/i8520.check

@@ -0,0 +1,3 @@
+List((A,+))
+List((B,-))
+List((C, ))

tests/run-macros/i8520/Macro_1.scala

@@ -0,0 +1,13 @@
+import scala.quoted._
+
+inline def test[T[_]]: Unit = ${ testExpr[T] }
+
+def testExpr[T[_]: Type](using QuoteContext): Expr[Unit] = {
+  import qctx.tasty._
+  def variance(f: Flags) =
+     if f.is(Flags.Covariant) then "+"
+     else if f.is(Flags.Contravariant) then "-"
+     else " "
+  val t = '[T].unseal.tpe.typeSymbol.typeMembers.map(x => (x.name, variance(x.flags)))
+  '{ println(${Expr(t.toString)}) }
+}

tests/run-macros/i8520/Test_2.scala

@@ -0,0 +1,9 @@
+trait X[+A]
+trait Y[-B]
+trait Z[C]
+
+@main def Test = {
+  test[X]
+  test[Y]
+  test[Z]
+}