As part of Understanding a spike in app compilation time, I’m trying to remove compile-time dependency that’s based on defguard macro.

With the code below, Elixir reports a transitive compile-time dependency:

mix xref graph --label compile-connected
lib/example1.ex
└── lib/guards.ex (compile)

How would one go about change the code to avoid the transitive dependency, while (ideally) preserving the defguard macros?

For context, this is a simplified example of production code. The reason lib/guards.ex is a separate file is code re-use - it’s typically included into other modules to offer the guards.

The code looks like this (repo is available here, for reference):

# lib/example1.ex
defmodule Example1 do
  import Example1.Guards

  def user(user) when is_admin(user), do: IO.puts("This user is an admin: #{inspect(user)}")

  def user(user) when is_customer(user), do: IO.puts("This user is a customer: #{inspect(user)}")
end

# lib/guards.ex
defmodule Example1.Guards do
  defguard is_admin(user) when is_struct(user, Example1.Admin) == "admin"

  defguard is_customer(user) when is_struct(user, Example1.Customer) == "customer"
end

# lib/admin.ex
defmodule Example1.Admin do
  defstruct role: :admin
end

# lib/customer.ex
defmodule Example1.Customer do
  defstruct role: :customer
end

Since both defguard and is_struct(anyVariable, AnyModule) are not supposed to make any function calls on the AnyModule - maybe there’s no reason to report a compile-time dependency in such case, is there?