Ignore lines when formatting specs, closes #2245

Author: josevalim

lib/ex_doc/language/elixir.ex

@@ -378,6 +378,7 @@ defmodule ExDoc.Language.Elixir do
   @impl true
   def format_spec(ast) do
     ast
+    |> normalize_spec_metadata()
     |> Macro.to_string()
     |> safe_format_string!()
     |> ExDoc.Utils.h()
@@ -650,6 +651,18 @@ defmodule ExDoc.Language.Elixir do
     end
   end
 
+  defp normalize_spec_metadata(ast) do
+    Macro.prewalk(ast, fn
+      {name, metadata, args} when is_atom(name) and is_list(metadata) and is_list(args) ->
+        # Elixir uses line metadata to decide when to break lines during stringification.
+        # Specs come from debug info, so we do not want line numbers to affect rendering.
+        {name, Keyword.delete(metadata, :line), args}
+
+      other ->
+        other
+    end)
+  end
+
   defp typespec_name({:"::", _, [{name, _, _}, _]}), do: Atom.to_string(name)
   defp typespec_name({:when, _, [left, _]}), do: typespec_name(left)
   defp typespec_name({name, _, _}) when is_atom(name), do: Atom.to_string(name)

test/ex_doc/formatter/html/templates_test.exs

@@ -481,6 +481,12 @@ defmodule ExDoc.Formatter.HTML.TemplatesTest do
     test "outputs the types and function specs", context do
       content = get_module_template([TypesAndSpecs, TypesAndSpecs.Sub], context)
       integer = ~s[<a href="https://elixir.hexdocs.pm/typespecs.html#basic-types">integer</a>()]
+      atom = ~s[<a href="https://elixir.hexdocs.pm/typespecs.html#basic-types">atom</a>()]
+
+      keyword =
+        ~s[<a href="https://elixir.hexdocs.pm/typespecs.html#built-in-types">keyword</a>()]
+
+      string_t = ~s[<a href="https://elixir.hexdocs.pm/String.html#t:t/0">String.t</a>()]
 
       public_html =
         ~S[<span class="attribute">@type</span> public(t) :: {t, ] <>
@@ -495,6 +501,10 @@ defmodule ExDoc.Formatter.HTML.TemplatesTest do
       assert content =~ ~s[A public type]
       assert content =~ ~s[<span class="attribute">@spec</span> add(]
       assert content =~ ~s[add(#{integer}, <a href="#t:opaque/0">opaque</a>()) :: #{integer}]
+
+      assert content =~
+               ~s[format_filters(#{keyword}, #{atom}) :: #{string_t}]
+
       refute content =~ ~s[minus(#{integer}, #{integer}) :: #{integer}]
 
       assert content =~

test/fixtures/types_and_specs.ex

@@ -28,6 +28,9 @@ defmodule TypesAndSpecs do
   @spec macro_with_spec(v) :: {:ok, v} when v: any()
   defmacro macro_with_spec(v), do: {:ok, v}
 
+  @spec format_filters(keyword(), atom()) :: String.t()
+  def format_filters(filters, _type), do: inspect(filters)
+
   @spec priv_macro_spec(any) :: {:no, any}
   defmacrop priv_macro_spec(v), do: {:no, v}