Fix retrieving specs for macros with when, closes #1191

lib/ex_doc/retriever.ex

@@ -559,6 +559,10 @@ defmodule ExDoc.Retriever do
     {:"::", info, [{name, info2, rest_args}, return]}
   end
 
+  defp remove_first_macro_arg({:when, meta, [lhs, rhs]}) do
+    {:when, meta, [remove_first_macro_arg(lhs), rhs]}
+  end
+
   defp find_module_line(%{abst_code: abst_code, name: name}) do
     Enum.find_value(abst_code, fn
       {:attribute, anno, :module, ^name} -> anno_line(anno)

test/ex_doc/retriever_test.exs

@@ -189,12 +189,17 @@ defmodule ExDoc.RetrieverTest do
 
     test "returns the specs for non-private macros" do
       [module_node] = docs_from_files(["TypesAndSpecs"])
-      [_, _, macro] = module_node.docs
+      [_, _, macro1, macro2] = module_node.docs
 
-      assert macro.id == "macro_spec/1"
-      assert macro.doc == nil
-      assert macro.type == :macro
-      assert Macro.to_string(macro.specs) == "[macro_spec(any()) :: {:ok, any()}]"
+      assert macro1.id == "macro_spec/1"
+      assert macro1.doc == nil
+      assert macro1.type == :macro
+      assert Macro.to_string(macro1.specs) == "[macro_spec(any()) :: {:ok, any()}]"
+
+      assert macro2.id == "macro_with_spec/1"
+      assert macro2.doc == nil
+      assert macro2.type == :macro
+      assert Macro.to_string(macro2.specs) == "[macro_with_spec(v) :: {:ok, v} when v: any()]"
     end
 
     test "returns the spec info for each non-private module type" do

test/fixtures/types_and_specs.ex

@@ -25,6 +25,9 @@ defmodule TypesAndSpecs do
   @spec macro_spec(any) :: {:ok, any}
   defmacro macro_spec(v), do: {:ok, v}
 
+  @spec macro_with_spec(v) :: {:ok, v} when v: any()
+  defmacro macro_with_spec(v), do: {:ok, v}
+
   @spec priv_macro_spec(any) :: {:no, any}
   defmacrop priv_macro_spec(v), do: {:no, v}