With an oversimplified mix project, I am unable to reproduce this:

defmodule Recompile.Schema do
  defmacro __schema__() do
    quote do
      "I do schema stuff!"
    end
  end
end

defmodule Recompile.Notation do
  defmacro __using__([schema: schema]) do
    quote do
      require unquote(schema)
      unquote(schema).__schema__()
    end
  end
end

defmodule Recompile.TestBed do
  use Recompile.Notation, schema: Recompile.Schema
end

$ mix xref graph --label compile --sink lib/recompile/schema.ex
lib/recompile/test_bed.ex
└── lib/recompile/schema.ex (compile)

and when I change Schema:

$ mix compile --verbose
Compiling 2 files (.ex)
Compiled lib/recompile/schema.ex
Compiled lib/recompile/test_bed.ex

Could you possibly share more code and your Elixir version? Is this in a mix project?

Yes, that is correct behaviour in this situation because it’s inside a function which makes it a runtime dependency.

Mostly, yes. Nothing outside of the returned quoted expression will be injected into Testbed so once that module is compiled, all that stuff is gone. So in this case it’s not that it isn’t interpreting Schema as anything other than the atom it’s that Schema isn’t even present in the compiled code! Again it’s hard to see without more context but there doesn’t seem to be anything about that code snippet that suggests you need Macro.expand over requireing or importing within a quote block which of course you want anyway to create the dependency. It depends what you’re trying to accomplish, of course.

I’ve also never actually seen ensure_compiled! used inside a module before. I’m not a master of macros, though, so maybe there is a good reason, but AFAIK, ensure_compiled! is essentially require for use outside of a defmodule. Don’t quote me on that, though