WIP: Construct trees for HOAS patterns respecting eta expansion

Author: zeptometer

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

@@ -11,6 +11,7 @@ import dotty.tools.dotc.core.Symbols.*
 import dotty.tools.dotc.util.optional
 import dotty.tools.dotc.core.Types
 import dotty.tools.dotc.core.Definitions
+import dotty.tools.dotc.ast.untpd
 
 /** Matches a quoted tree against a quoted pattern tree.
  *  A quoted pattern tree may have type and term holes in addition to normal terms.
@@ -508,14 +509,30 @@ object QuoteMatcher {
           case Block(List(DefDef(nme.ANON_FUN, _, _, Apply(Ident(name), _))), _) => name.asTermName
           case arg => arg.symbol.name.asTermName
         }
-        val paramTypes = args.map(x => mapTypeHoles(x.tpe.widenTermRefExpr))
+        val paramTypes = args.map(x => adaptTypes(mapTypeHoles(x.tpe.widenTermRefExpr)))
         val methTpe = MethodType(names)(_ => paramTypes, _ => mapTypeHoles(patternTpe))
         val meth = newAnonFun(ctx.owner, methTpe)
         def bodyFn(lambdaArgss: List[List[Tree]]): Tree = {
           val argsMap = args.view.map(_.symbol).zip(lambdaArgss.head).toMap
           val body = new TreeMap {
             override def transform(tree: Tree)(using Context): Tree =
               tree match
+                /*
+                 * When matching a method call `f(0)` against a HOAS pattern `p(g)` where
+                 * f has a method type `(x: Int): Int` and  `f` maps to `g`, `p` should be `g.apply(0)`
+                 * because the type of `g` is `Int => Int` due to eta expansion.
+                 *
+                 * Remaining TODOs from issue-17105
+                 * * [ ] cover the case of nested method call
+                 * * [ ] contextual params?
+                 * * [ ] erasure types?
+                 */
+                case Apply(methId: Ident, args) =>
+                  val fnId = env.get(tree.symbol).flatMap(argsMap.get).getOrElse(tree)
+                  ctx.typer.typed(
+                    untpd.Apply(
+                      untpd.Select(untpd.TypedSplice(fnId), nme.apply),
+                      args.map(untpd.TypedSplice(_))))
                 case tree: Ident => env.get(tree.symbol).flatMap(argsMap.get).getOrElse(tree)
                 case tree => super.transform(tree)
           }.transform(tree)

tests/run-macros/i17105/Macro_1.scala

@@ -1,30 +1,37 @@
 import scala.quoted.*
 
-inline def test1: String =  ${ testExpr1 }
-def testExpr1(using Quotes): Expr[String] =
-  '{ def f(x: Int) = 1; val n = 2; f(n) } match
-    case '{ def g(y: Int) = 1; val n = 2; $a(g, n): Int } =>  Expr(a.show)
+inline def testExpr(inline body: Any) = ${ testExprImpl('body) }
+def testExprImpl(body: Expr[Any])(using Quotes): Expr[String] =
+  body match
+    case '{ def g(y: Int) = "hello" * y; $a(g): String } =>
+      '{ $a((z:Int) => "this is " + z.toString()) }
     case _ => Expr("not matched")
 
-inline def test2: String = ${ testExpr2 }
-def testExpr2(using Quotes): Expr[String] =
-  '{ def f(x: Int, y:Int) = 1; f(1, 2) } match
-    case '{ def g(y: Int, z:Int) = 1; $a(g): Int } =>  Expr(a.show)
-    case _ => Expr("not matched")
+// TODO issue-17105: Clean this up if not neccessary
+// inline def test1: String =  ${ testExpr1 }
+// def testExpr1(using Quotes): Expr[String] =
+//   '{ def f(x: Int) = 1; val n = 2; f(n) } match
+//     case '{ def g(y: Int) = 1; val n = 2; $a(g, n): Int } =>  Expr(a.show)
+//     case _ => Expr("not matched")
 
-inline def test3: String = ${ testExpr3 }
-def testExpr3(using Quotes): Expr[String] =
-  '{
-      def f1(using Ordered[Int]) =
-        def f2(using Ordered[Int]) =
-          1 < 2
-        f2 || 2 < 3: Boolean
-   } match
-    case '{
-      def g1(using ord: Ordered[Int]) =
-        def g2(using Ordered[Int]) =
-          1 < 2
-        $a(g2, ord): Boolean
-    } => Expr(a.show)
-    case _ => Expr("not matched")
+// inline def test2: String = ${ testExpr2 }
+// def testExpr2(using Quotes): Expr[String] =
+//   '{ def f(x: Int, y:Int) = 1; f(1, 2) } match
+//     case '{ def g(y: Int, z:Int) = 1; $a(g): Int } =>  Expr(a.show)
+//     case _ => Expr("not matched")
 
+// inline def test3: String = ${ testExpr3 }
+// def testExpr3(using Quotes): Expr[String] =
+//   '{
+//       def f1(using Ordered[Int]) =
+//         def f2(using Ordered[Int]) =
+//           1 < 2
+//         f2 || 2 < 3: Boolean
+//    } match
+//     case '{
+//       def g1(using ord: Ordered[Int]) =
+//         def g2(using Ordered[Int]) =
+//           1 < 2
+//         $a(g2, ord): Boolean
+//     } => Expr(a.show)
+//     case _ => Expr("not matched")

tests/run-macros/i17105/Test_2.scala

@@ -1,4 +1,2 @@
-@main def Test: Unit =
-  println(test1)
-  println(test2)
-  println(test3)
+@main def app: Unit =
+  testExpr { def f(x: Int) = "hello" * x; f(0) + "bye" }