Crash when defining a function without args via unquote fragment

[lukaszsamson]

Elixir and Erlang/OTP versions

Erlang/OTP 27 [erts-15.2.5] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit]

Elixir 1.18.3 (compiled with Erlang/OTP 27)

Operating system

any

Current behavior

defmodule A do; def unquote(:"foo-bar"), do: :ok; end

error: invalid syntax in def :"foo-bar"
└─ iex:20: A (module)

** (CompileError) iex: cannot compile module A (errors have been logged)
    (elixir 1.18.3) src/elixir_def.erl:149: :elixir_def.store_definition/5
    iex:20: (module)
    (elixir 1.18.3) src/elixir_compiler.erl:77: :elixir_compiler.dispatch/4
    (elixir 1.18.3) src/elixir_compiler.erl:52: :elixir_compiler.compile/4
    (elixir 1.18.3) src/elixir_module.erl:454: :elixir_module.eval_form/7
    (elixir 1.18.3) src/elixir_module.erl:156: :elixir_module.compile/7
    iex:20: (file)

The version with params works as expected

defmodule A do; def unquote(:"foo-bar")(), do: :ok; end

The docs in https://hexdocs.pm/elixir/Kernel.SpecialForms.html#quote/2-binding-and-unquote-fragments does not state that it is forbidden
The docs in https://hexdocs.pm/elixir/1.18.3/Kernel.html#def/2 encourage to use paramsless form in the first example

Expected behavior

No crash or docs updated to mention that params are required on defs with unquote fragments

[josevalim]

I can update the docs to provide be a bit clearer though but the behaviour is expected as you are literally defining:

def :foo do

end