c.Tree in macro bundle method result type does not compile, while Tree does

[Vladimir Matveev]

Consider this code:

package example

import scala.reflect.macros.whitebox
import scala.language.experimental.macros

object Example {
  def generate[T] = macro ExampleBundle.doSomethingImpl[T]
}

@macrocompat.bundle
class ExampleBundle(val c: whitebox.Context) {
  import c.universe._

  //def doSomethingImpl[T: WeakTypeTag]: Tree = ???
  def doSomethingImpl[T: WeakTypeTag]: c.Tree = ???
}

It does not compile:

> compile
[info] Compiling 1 Scala source to /home/netvl/dev/lang/scala/macro-compat-tree-problem/target/scala-2.10/classes...
[error] /home/netvl/dev/lang/scala/macro-compat-tree-problem/src/main/scala/example.scala:7: value doSomethingImpl is not a member of object example.ExampleBundle
[error]   def generate[T] = macro ExampleBundle.doSomethingImpl[T]
[error]                                         ^

According to -Ymacro-debug-lite output, the macro bundle method has no corresponding forwarding method in the generated companion object. However, if you uncomment the top line instead of the bottom one:

  def doSomethingImpl[T: WeakTypeTag]: Tree = ???
  //def doSomethingImpl[T: WeakTypeTag]: c.Tree = ???

then everything compiles correctly.

It seems that this happens because of too naive resolution of Tree type during the generation of the forwarding methods.