Add support for rendering equiv metadata

lib/ex_doc/language/erlang.ex

@@ -64,19 +64,19 @@ defmodule ExDoc.Language.Erlang do
 
  @impl true
  def function_data(entry, module_data) do
- {{kind, name, arity}, _anno, _signature, doc_content, _metadata} = entry
+ {{kind, name, arity}, _anno, _signature, doc_content, metadata} = entry
 
  # TODO: Edoc on Erlang/OTP24.1+ includes private functions in
  # the chunk, so we manually yank them out for now.
  if kind == :function and doc_content != :hidden and
  function_exported?(module_data.module, name, arity) do
- function_data(name, arity, doc_content, module_data)
+ function_data(name, arity, doc_content, module_data, metadata)
  else
  :skip
  end
  end
 
- defp function_data(name, arity, _doc_content, module_data) do
+ defp function_data(name, arity, _doc_content, module_data, metadata) do
  specs =
  case Map.fetch(module_data.private.specs, {name, arity}) do
  {:ok, specs} ->
@@ -93,7 +93,26 @@ defmodule ExDoc.Language.Erlang do
  end
 
  %{
- doc_fallback: fn -> nil end,
+ doc_fallback: fn ->
+ case metadata[:equiv] do
+ nil ->
+ nil
+
+ equiv when is_binary(equiv) ->
+ ## We try to parse the equiv in order to link to the target
+ with {:ok, toks, _} <- :erl_scan.string(:unicode.characters_to_list(equiv <> ".")),
+ {:ok, [{:call, _, {:atom, _, func}, args}]} <- :erl_parse.parse_exprs(toks) do
+ "Equivalent to [`#{equiv}`](`#{func}/#{length(args)}`)"
+ else
+ _ -> "Equivalent to `#{equiv}`"
+ end
+ |> ExDoc.DocAST.parse!("text/markdown")
+
+ equiv ->
+ IO.warn("invalid equiv: #{inspect(equiv)}", [])
+ nil
+ end
+ end,
  extra_annotations: [],
  line: nil,
  specs: specs