Check trivial trait args

som-snytt · som-snytt · commit 41aafb71f794 · 2025-04-01T03:14:39.000-07:00
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1599,12 +1599,11 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
 
       def cookIfNeeded(tpt: Tree) = if (context.unit.isJava) tpt modifyType rawToExistential else tpt
       cookIfNeeded(if (probe.isTrait || inMixinPosition) {
-        if (!argssAreTrivial) {
-          if (probe.isTrait) ConstrArgsInParentWhichIsTraitError(encodedtpt, probe)
-          else () // a class in a mixin position - this warrants an error in `validateParentClasses`
+        if (probe.isTrait && inMixinPosition && !argss.isEmpty)
+          ConstrArgsInParentWhichIsTraitError(encodedtpt, probe)
+                  // a class in a mixin position - this warrants an error in `validateParentClasses`
                   // therefore here we do nothing, e.g. don't check that the # of ctor arguments
                   // matches the # of ctor parameters or stuff like that
-        }
         typedType(decodedtpt)
       } else {
         val supertpt = typedTypeConstructor(decodedtpt)
@@ -1757,8 +1756,9 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
       case Nil => List(atPos(templ.pos)(TypeTree(AnyRefTpe)))
       case first :: rest =>
         try {
+          val firstMixin = !context.owner.isAnonymousClass // permit new T() {} syntax
           val supertpts = fixDuplicateSyntheticParents(normalizeFirstParent(
-            typedParentType(first, templ, inMixinPosition = false) +:
+            typedParentType(first, templ, inMixinPosition = firstMixin) +:
             (rest map (typedParentType(_, templ, inMixinPosition = true)))))
 
           // if that is required to infer the targs of a super call
diff --git a/test/files/neg/t6805.check b/test/files/neg/t6805.check
@@ -0,0 +1,13 @@
+t6805.scala:4: error: trait T is a trait; does not take constructor arguments
+class C extends T() // error
+                ^
+t6805.scala:7: error: trait T is a trait; does not take constructor arguments
+class Y extends X with T() // error
+                       ^
+t6805.scala:11: error: trait T is abstract; cannot be instantiated
+  def u: T = new T()  // error
+             ^
+t6805.scala:12: error: trait T is a trait; does not take constructor arguments
+  def v: T = new X with T()  // error
+                        ^
+4 errors
diff --git a/test/files/neg/t6805.scala b/test/files/neg/t6805.scala
@@ -0,0 +1,14 @@
+
+trait T
+
+class C extends T() // error
+
+class X
+class Y extends X with T() // error
+
+object funcs {
+  def t: T = new T() {} // no error, permissive for Java anon syntax, just because
+  def u: T = new T()  // error
+  def v: T = new X with T()  // error
+  def w: T = new T {}
+}
diff --git a/test/files/pos/t6666d.scala b/test/files/pos/t6666d.scala
@@ -4,7 +4,7 @@ import scala.math.Ordering
 
 class Test[K](param:TreeMap[K,Int]){
   def this() = this({
-    implicit object TreeOrd extends Ordering[K](){
+    implicit val TreeOrd: Ordering[K] = new Ordering[K] {
       def compare(a: K, b: K) = {
         -1
       }
diff --git a/test/tasty/run/src-2/tastytest/TestGreeting.scala b/test/tasty/run/src-2/tastytest/TestGreeting.scala
@@ -6,6 +6,6 @@ object TestGreeting extends Suite("TestGreeting") {
     final val greeting = "Hello, World!"
   }
 
-  test(assert(new Greeter with Hello().accessGreeting === "Hello, World!"))
+  test(assert((new Greeter with Hello).accessGreeting === "Hello, World!"))
 
 }
diff --git a/test/tasty/run/src-2/tastytest/TestInner.scala b/test/tasty/run/src-2/tastytest/TestInner.scala
@@ -3,6 +3,6 @@ package tastytest
 object TestInner extends Suite("TestInner") {
 
   test(assert(Inner.Foo.Bar != null))
-  test(assert(new Inner.Foo(){}.isInstanceOf[Inner.Foo]))
+  test(assert(new Inner.Foo {}.isInstanceOf[Inner.Foo]))
 
 }
diff --git a/test/tasty/run/src-2/tastytest/TestReader.scala b/test/tasty/run/src-2/tastytest/TestReader.scala
@@ -2,7 +2,7 @@ package tastytest
 
 object TestReader extends Suite("TestReader") {
 
-  implicit def mkReaderMonad[Ctx]: Reader[Ctx] = new Reader[Ctx]() {}
+  implicit def mkReaderMonad[Ctx]: Reader[Ctx] = new Reader[Ctx] {}
 
   def pureToString[F[_], A](fa: F[A])(implicit F: Monad[F]): F[String] =
     F.flatMap(fa)(a => F.pure(a.toString))

Original file line number	Diff line number	Diff line change
`@@ -4,7 +4,7 @@ import scala.math.Ordering`
`4`	`4`
`5`	`5`	`class Test[K](param:TreeMap[K,Int]){`
`6`	`6`	`def this() = this({`
`7`		`- implicit object TreeOrd extends Ordering[K](){`
	`7`	`+ implicit val TreeOrd: Ordering[K] = new Ordering[K] {`
`8`	`8`	`def compare(a: K, b: K) = {`
`9`	`9`	`-1`
`10`	`10`	`}`
Original file line number	Diff line number	Diff line change
`@@ -6,6 +6,6 @@ object TestGreeting extends Suite("TestGreeting") {`
`6`	`6`	`final val greeting = "Hello, World!"`
`7`	`7`	`}`
`8`	`8`
`9`		`- test(assert(new Greeter with Hello().accessGreeting === "Hello, World!"))`
	`9`	`+ test(assert((new Greeter with Hello).accessGreeting === "Hello, World!"))`
`10`	`10`
`11`	`11`	`}`
Original file line number	Diff line number	Diff line change
`@@ -3,6 +3,6 @@ package tastytest`
`3`	`3`	`object TestInner extends Suite("TestInner") {`
`4`	`4`
`5`	`5`	`test(assert(Inner.Foo.Bar != null))`
`6`		`- test(assert(new Inner.Foo(){}.isInstanceOf[Inner.Foo]))`
	`6`	`+ test(assert(new Inner.Foo {}.isInstanceOf[Inner.Foo]))`
`7`	`7`
`8`	`8`	`}`