Merge pull request #14057 from dotty-staging/fix-14010

Handle hoisted super arguments correctly in elimByName

Author: odersky

compiler/src/dotty/tools/dotc/transform/HoistSuperArgs.scala

@@ -88,7 +88,7 @@ class HoistSuperArgs extends MiniPhase with IdentityDenotTransformer { thisPhase
       def newSuperArgMethod(argType: Type) = {
         val (staticFlag, methOwner) =
           if (cls.owner.is(Package)) (JavaStatic, cls) else (EmptyFlags, cls.owner)
-        val argTypeWrtConstr = argType.subst(origParams, allParamRefs(constr.info))
+        val argTypeWrtConstr = argType.widenTermRefExpr.subst(origParams, allParamRefs(constr.info))
         // argType with references to paramRefs of the primary constructor instead of
         // local parameter accessors
         newSymbol(

compiler/src/dotty/tools/dotc/transform/TransformByNameApply.scala

@@ -11,7 +11,8 @@ import Types._
 import Flags._
 import Decorators._
 import DenotTransformers._
-import core.StdNames.nme
+import StdNames.nme
+import NameKinds.SuperArgName
 import ast.Trees._
 import reporting.trace
 
@@ -51,7 +52,8 @@ abstract class TransformByNameApply extends MiniPhase { thisPhase: DenotTransfor
             if qual.tpe.derivesFrom(defn.Function0) && (isPureExpr(qual) || qual.symbol.isAllOf(Inline | Param)) =>
               wrap(qual)
             case _ =>
-              if (isByNameRef(arg) || arg.symbol == defn.cbnArg) arg
+              if isByNameRef(arg) || arg.symbol == defn.cbnArg || arg.symbol.name.is(SuperArgName)
+              then arg
               else wrap(mkByNameClosure(arg, argType))
           }
         case _ =>

tests/pos/i14010.scala

@@ -0,0 +1,46 @@
+abstract class LazyList[+T] {
+  def head: T
+  def tail: LazyList[T]
+  def isEmpty: Boolean
+  def push[E >: T](top: => E): LazyList[E] =
+    new Push[E](top, this)
+  //def map[R](f: T => R): LazyList[R]
+  def append[E >: T](that: => LazyList[E]): LazyList[E]
+}
+
+private class Push[+T](top: => T, stack: => LazyList[T]) extends LazyList[T] {
+  override def head: T =
+    top
+  override def tail: LazyList[T] =
+    stack
+  override def isEmpty: Boolean =
+    false
+  //override def map[R](f: T => R): LazyList[R] =
+  //  new Push[R](f(top), stack.map(f)) {
+  //        override def map[R2](f2: R => R2): LazyList[R2] =
+  //          Push.this.map(f2 compose f)
+  //      }
+  override def append[E >: T](that: => LazyList[E]): LazyList[E] =
+    new Push[E](top, stack.append(that)) {
+          override def append[E2 >: E](that2: => LazyList[E2]): LazyList[E2] =
+            Push.this.append(that.append(that2))
+        }
+}
+
+object LazyList {
+  val empty =
+    new LazyList[Nothing] {
+          override def head: Nothing =
+            throw new NoSuchElementException
+          override def tail: LazyList[Nothing] =
+            throw new UnsupportedOperationException
+          override def isEmpty: Boolean =
+            true
+          //override def map[R](f: _ => R): LazyList[R] =
+          //  this
+          override def append[E](that: => LazyList[E]): LazyList[E] =
+            that
+        }
+  def apply[T](elements: T*): LazyList[T] =
+    elements.foldRight[LazyList[T]](empty)(new Push(_, _))
+}

tests/pos/i14010a.scala

@@ -0,0 +1,3 @@
+class Foo(top: => Int) {
+  def foo: Any = new Foo(top) { }
+}