Add regression tests

with prototype of places macro

Author: nicolasstucki

tests/run-macros/places-proto.check

@@ -0,0 +1,2 @@
+2
+List(3, 2, 4)

tests/run-macros/places-proto/Macros_1.scala

@@ -0,0 +1,40 @@
+import scala.quoted.*
+
+object Places:
+  def withPlace[T: Type, R: Type](x: Expr[T])(body: Quotes ?=> Place[T] => Expr[R])(using Quotes): Expr[R] = {
+    x match
+      case '{ ($arr: Array[T]).apply($index) } => // TODO use more general version using reflection (apply/update methods)
+        '{
+          val idx = $index
+          ${
+            body(
+              new Place[T]:
+                def set(x: Expr[T]): Expr[Unit] = '{ $arr(idx) = $x }
+                def get: Expr[T] = '{ $arr(idx) }
+            )
+          }
+        }
+      case '{ $x: T } =>
+        import quotes.reflect.*
+        x.asTerm match
+          case ident: Ident if ident.symbol.flags.is(Flags.Mutable) =>
+            body(
+              new Place[T]:
+                def set(x: Expr[T]): Expr[Unit] = Assign(ident, x.asTerm).asExprOf[Unit]
+                def get: Expr[T] = x
+            )
+          case Apply(Select(place, "apply"), List(idx)) => // TODO check that place has an update method
+            '{???} // TODO
+          case tree =>
+            throw new MatchError(tree.show(using Printer.TreeStructure))
+  }
+
+  trait Place[T]:
+    def set(x: Expr[T]): Expr[Unit]
+    def get: Expr[T]
+
+
+inline def increment(inline x: Int): Unit = ${ incrementExpr('x) } // TODO generalize to Numeric types
+
+private def incrementExpr(x: Expr[Int])(using Quotes): Expr[Unit] =
+  Places.withPlace(x) { place => place.set('{ ${place.get} + 1 }) }

tests/run-macros/places-proto/Test_2.scala

@@ -0,0 +1,11 @@
+
+@main def Test: Unit =
+  var x = 1
+  increment(x)
+  println(x)
+
+  val arr = Array(1, 2, 3)
+  increment(arr(0))
+  increment(arr(0))
+  increment(arr(2))
+  println(arr.toList)