Scala 2.13 regression: type param affecting overload #12663
Description
Compiler version
3.0.0
Minimized code (ver 1)
final class HookComponentBuilder[Ctx, CtxFn[_]] { def asd[A](f: Ctx => A): A = ??? def asd[A](f: CtxFn[A]): A = ??? } object HookCtx { case class P1[P, H1](props: P, hook1: H1) } object HookCtxFn { sealed trait P1[P, H1] { type Fn[A] = (P, H1) => A } } object Test { val b: HookComponentBuilder[HookCtx.P1[String, Int], HookCtxFn.P1[String, Int]#Fn] = ??? b.asd($ => $.props.length + $.hook1) b.asd((props, hook1) => props.length + hook1) }Minimized code (ver 2)
Changing HookCtxFn.P1 to a type lambda...
final class HookComponentBuilder[Ctx, CtxFn[_]] { def asd[A](f: Ctx => A): A = ??? def asd[A](f: CtxFn[A]): A = ??? } object HookCtx { case class P1[P, H1](props: P, hook1: H1) } object HookCtxFn { type P1[P, H1] = [A] =>> (P, H1) => A } object Test { val b: HookComponentBuilder[HookCtx.P1[String, Int], HookCtxFn.P1[String, Int]] = ??? b.asd($ => $.props.length + $.hook1) b.asd((props, hook1) => props.length + hook1) }Output
[error] 18 | b.asd((props, hook1) => props.length + hook1) [error] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [error] | Wrong number of parameters, expected: 1Expectation
It should compile. It does with Scala 2.13
Workaround
Inlining HookCtxFn.P1 makes it work.
final class HookComponentBuilder[Ctx, CtxFn[_]] { def asd[A](f: Ctx => A): A = ??? def asd[A](f: CtxFn[A]): A = ??? } object HookCtx { case class P1[P, H1](props: P, hook1: H1) } object Test { val b: HookComponentBuilder[HookCtx.P1[String, Int], [A] =>> (String, Int) => A] = ??? b.asd($ => $.props.length + $.hook1) b.asd((props, hook1) => props.length + hook1) }