Typedef quasi-macro `record` fails when the macro name is customized

[adamwight]

Elixir and Erlang/OTP versions

Erlang/OTP 27 [erts-15.2.3] [source-e02b4e39b5] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit:ns]

Elixir 1.18.3 (compiled with Erlang/OTP 27)

Operating system

Linux (Debian 13.2)

Current behavior

Minimal case:

defmodule CustomType do
  require Record
  Record.defrecord(:new, :custom_name, field: :undefined)
  @type t :: record(:custom_name, field: term())
end

Output:

** (Kernel.TypespecError) iex:89: unknown record :custom_name
    (elixir 1.18.3) lib/kernel/typespec.ex:980: Kernel.Typespec.compile_error/2
    (elixir 1.18.3) lib/kernel/typespec.ex:308: Kernel.Typespec.translate_type/2
    (stdlib 6.2.1) lists.erl:2343: :lists.mapfoldl_1/3
    (elixir 1.18.3) lib/kernel/typespec.ex:235: Kernel.Typespec.translate_typespecs_for_module/2
    (elixir 1.18.3) src/elixir_erl.erl:140: :elixir_erl.compile/1
    (elixir 1.18.3) src/elixir_module.erl:216: anonymous fn/9 in :elixir_module.compile/7
    iex:86: (file)

Expected behavior

I would expect the code to work the same as in this example where the record function name was not customized:

defmodule CustomType do
  require Record
  Record.defrecord(:custom_name, field: :undefined)
  @type t :: record(:custom_name, field: term())
end

(no error)

[adamwight]

The issue seems to be that Macro.expand assumes the record name is already defined as the function, so in the working example it becomes something like custom_name() and in the broken example it should have been new().

Side note: it seems problematic that record/2 is mentioned in the documentation as a macro, when in fact seems to be hardcoded into typespec.ex and documentation is lacking in the obvious places.

[josevalim]

This looks correct to me. The record name is :new, the tag name is :custom_name. The tag is completely internal and should not impact other usages.

[adamwight]

Thanks for checking—so the arguments to the record/2 construct are (name :: atom, fields :: keyword) and my typedef should have looked like this:

defmodule CustomType do
  require Record
  Record.defrecord(:new, :custom_name, field: :undefined)
  @type t :: record(:new, field: term())
end

That works!

[josevalim]

Yes!!!!! 🎉