Question

Why does the following code works:

class X

class A(implicit c: X)
class B(arg: Int)(implicit c: X) extends A
class C(arg: Int)(implicit c: X) extends B(arg)

But not this one:

class X

class A(implicit c: X)
class B[T](arg: T)(implicit c: X) extends A
class C(arg: Int)(implicit c: X) extends B(arg)

Which fails with the following error:

error: could not find implicit value for parameter c: core.X

class C(arg: Int)(implicit c: X) extends B(arg)

Answer 1

It seems to work if you help the type inferencer when calling the constructor for B:

class X

class A(implicit c: X)
class B[T](arg: T)(implicit c: X) extends A
class C(arg: Int)(implicit c: X) extends B[Int](arg)

So it doesn’t look like a fundamental limitation. But the error message which you didn’t include is very unhelpful could not find implicit value for parameter c: X.