Is there a way to get mix xref to show me exports that are not used

Just as a clarification - mix xref has nothing to do with the Erlang’s xref module. Elixir does its own analysis based on data gathered during compilation of Elixir modules. The Erlang’s xref was just too slow to run on every compilation like the Elixir’s analysis does.

I see… OK. In any case, is there any way to use it to find functions that a module exports but no other module uses in my codebase?

I have checked and it should be possible to do so. I am working on simple mix task that will be able to do so.

First “quick and dirty” example GitHub - hauleth/mix_unused: Find unused functions in your project · GitHub. Adds new mix command mix unused that will list unused functions.

You may want to try:

server = :my_xref_server
{:ok, pid} = :xref.start(server)
Enum.each(:code.get_path(), &:xref.add_directory(server, &1, {:warnings, false}))
{:ok, unused_exports} = :xref.q(server, ~c"X - XU")

Here X - XU is a query that means "Exported" minus "Exported and Used", which essentially leaves you with Exported and Unused. See these references for more advanced queries and a reference:

• xref — OTP 29.0.2 (tools 4.2.1)
• Xref - The Cross Reference Tool — OTP 29.0.2 (tools 4.2.1)

But be prepare to do some aggressive filtering of the results. For example, drop modules not belonging to your app, structs, etc.