Handle poly functions

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Semantic.scala

@@ -555,6 +555,14 @@ class Semantic {
         case _ =>
           ??? // impossible
 
+      case PolyFun(body) =>
+        thisV match
+          case obj: (ThisRef | Warm) =>
+            val value = Fun(body, obj, klass)
+            Result(value, Nil)
+          case _ =>
+            ??? // impossible
+
       case Block(stats, expr) =>
         val ress = eval(stats, thisV, klass)
         eval(expr, thisV, klass) ++ ress.flatMap(_.errors)
@@ -829,7 +837,7 @@ object Semantic {
       case TypeApply(fn, targs) =>
         unapply(fn)
 
-      case ref: RefTree if ref.symbol.is(Flags.Method) =>
+      case ref: RefTree if ref.tpe.widenSingleton.isInstanceOf[MethodicType] =>
         Some((ref, Nil))
 
       case _ => None
@@ -844,6 +852,19 @@ object Semantic {
       case _ => None
   }
 
+  object PolyFun {
+    def unapply(tree: Tree)(using Context): Option[Tree] =
+      tree match
+      case Block((cdef: TypeDef) :: Nil, Typed(NewExpr(tref, _, _, _), _))
+      if tref.symbol.isAnonymousClass && tref <:< defn.PolyFunctionType
+      =>
+        val body = cdef.rhs.asInstanceOf[Template].body
+        val apply = body.head.asInstanceOf[DefDef]
+        Some(apply.rhs)
+      case _ =>
+        None
+  }
+
   extension (symbol: Symbol) def hasSource(using Context): Boolean =
     !symbol.defTree.isEmpty
 

tests/init/neg/polyfun.scala

@@ -0,0 +1,8 @@
+class Test {
+  val m: [T] => (arg: T) => T =
+    [T] => (arg: T) => {
+      println(n)
+      arg
+    }
+  val n = m.apply(arg = 23)
+}

tests/init/neg/super.scala

@@ -20,11 +20,11 @@ class Bar extends A, B, C:
 
   override def foo() = n * n
 
-  val n = 10
+  val n = 10  // error
 
 class Qux extends A, B, C:
   super.foo()
 
   override def foo() = n * n
 
-  val n = 10
+  val n = 10 // error