如何检查WeakTypeTag或Type是否代表具体类型？

Question

How do I check if WeakTypeTag or Type represents concrete type? This would be especially useful in macros, where I could use it to raise compilation error when type given by the user is not concrete:

def macroMethod[T]: Unit = macro macroMethod_impl[T]

def macroMethod_impl[T: c.WeakTypeTag](c: Context): c.Expr[Unit] = {
  import c.universe._

  def isConcrete(tpe: Type) = ???

  if(!isConcrete(weakTypeOf[T])) {
    c.error(c.enclosingPosition, "You must provide concrete type.")
  }

  c.literalUnit
}

Answer 1

I think this will do the trick:

def isConcrete(tpe: Type) = !tpe.typeSymbol.asType.isAbstractType

then

scala> macroMethod[Int]

scala> class C[T] { macroMethod[T] }
<console>:10: error: You must provide concrete type.
       class C[T] { macroMethod[T] }