whitebox/blackbox abort behaviour difference.

gistfile1.scala

import scala.language.experimental.macros

import scala.reflect.macros.whitebox

trait Foo[T]

object Foo {
  implicit def mkFoo[T]: Foo[T] = macro FooMacros.mkFooImpl[T]
}

// with whitebox.Context the abort message is lost
// with blackbox.Context the abort message is preserved
class FooMacros(val c: whitebox.Context) {
  import c.universe._

  def mkFooImpl[T](implicit tTag: WeakTypeTag[T]): Tree = {
    val tTpe = weakTypeOf[T]
    val t = c.inferImplicitValue(tTpe, silent = true)
    if(t == EmptyTree)
      c.abort(c.enclosingPosition, "Custom missing implicit")

    q""" new Foo[$tTpe] """
  }
}