Implicit macros not found in Scala 2.10.1?

Question

It seems like the implicit keyword doesn't work when applied to macro defs.

For example, take the following code:

// Compilation unit A:
case class Foo[A]
// end A.

// Compilation unit B:
implicit def implicitFoo[A]: Foo[A] = macro implicitFoo_impl[A]

def implicitFoo_impl[A](c: Context): c.Expr[Foo[A]] =
  c.universe.reify(Foo[A])
// end B.

// Compilation unit C:
implicitly[Foo[Int]] // Fails with "could not find implicit value for parameter e: Foo[Int]
// end C.

The implicitly[Foo[Int]] fails, but it shouldn't; if I replace implicit def implicitFoo[A]: Foo[A] = macro implicitFoo_impl[A] with implicit def implicitFoo[A]: Foo[A] = ???, compilation succeeds.

Is this a bug or user error?

Answer 1

This is caused by https://issues.scala-lang.org/browse/SI-5923, which is fixed in master (2.11.0-SNAPSHOT), and which I'm planning to backport to 2.10.2. See more information (including potential problems which might prevent me from making it in time for 2.10.2) on the aforementioned JIRA page.