object MacroExample {
  def foo(xs: Int*): Any = macro foo_impl
  def foo_impl(c: Context)(ys: c.Expr[Int]*) = ???
}

import language.experimental.macros
import scala.reflect.macros.Context

object MacroExample {
  def foo(xs: Int*): Any = macro foo_impl
  def foo_impl(c: Context)(xs: c.Expr[Int]*) = xs.head

  def bar(xs: Int*): Any = macro bar_impl
  def bar_impl(c: Context)(xs: c.Expr[Int]*) = {
    import c.universe._

    xs.head.tree match {
      case Typed(e, _) => c.Expr(e)
      case i => c.Expr(i)
    }
  }
}

scala> MacroExample.foo(List(1, 2, 3): _*)
<console>:8: error: no `: _*' annotation allowed here
(such annotations are only allowed in arguments to *-parameters)
              MacroExample.foo(List(1, 2, 3): _*)
                                            ^

scala> MacroExample.bar(List(1, 2, 3): _*)
res0: List[Int] = List(1, 2, 3)

scala> MacroExample.bar(1, 2, 3)
res1: Int = 1