Add regression test

This add a prototype implementation for providing precise types without
the overhead of quote pattern matching.

Author: nicolasstucki

tests/pos-macros/quoted-with-precise-types.scala

@@ -0,0 +1,41 @@
+import scala.quoted.*
+
+def withType[T <: AnyKind, U](tpe: Type[T])(body: [X <: T] => Type[X] ?=> U)(using Quotes): U =
+  type X <: T
+  val tpeX: Type[X] = tpe.asInstanceOf[Type[X]]
+  body[X](using tpeX)
+
+def test1(t1: Type[?], t2: Type[? <: Any])(using Quotes) =
+  withType(t1) { [T <: AnyKind] => _ ?=> // TODO remove _ ?=> // Implementation restriction: polymorphic function literals must have a value parameter
+    Type.of[T]
+    Type.show[T]
+  }
+  withType(t2) { [T] => _ ?=> // TODO remove _ ?=>
+    '{ val a: T = ??? }
+    Type.of[T]
+    Type.show[T]
+  }
+  withType(t2):
+    [T] => _ ?=> '{ val a: T = ??? } // TODO remove _ ?=>
+
+def exprWithPreciseType[T, U](expr: Expr[T])(body: [X <: T] => Type[X] ?=> Expr[X] => U)(using Quotes): U =
+  import quotes.reflect.*
+  type X <: T
+  val exprX = expr.asInstanceOf[Expr[X]]
+  val tpeX = expr.asTerm.tpe.asType.asInstanceOf[Type[X]]
+  body[X](using tpeX)(exprX)
+
+def test2(x: Expr[Any])(using Quotes) =
+  // exprWithPreciseType(x) { [T] => x => // Inference limitation: x is assumed to be the Type[T] instead of the Expr[T]
+  exprWithPreciseType(x) { [T] => _ ?=> x => // TODO remove _ ?=>
+    Type.of[T]
+    '{ val a: T = $x }
+  }
+  exprWithPreciseType('{1}) { [T <: Int] => _ ?=> x => // TODO remove _ ?=>
+    Type.of[T]
+    '{ val a: Int = $x }
+    '{ val a: T = $x }
+    '{ val a: T = i($x) }
+  }
+
+def i[T <: Int](x: T): T = x