From 94ee934039d9434cea155ed55603d0a8fe62effe Mon Sep 17 00:00:00 2001
From: Alex Gubarev <gubarev.alex@gmail.com>
Date: Tue, 28 Jul 2026 12:44:41 +0300
Subject: [PATCH] Fix IEx.Helpers.h print spec for default arg function

---
 lib/iex/lib/iex/introspection.ex  | 21 +++++++++++++++++++--
 lib/iex/test/iex/helpers_test.exs |  7 +++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/lib/iex/lib/iex/introspection.ex b/lib/iex/lib/iex/introspection.ex
index 31f412bd20d..7e59bbccef6 100644
--- a/lib/iex/lib/iex/introspection.ex
+++ b/lib/iex/lib/iex/introspection.ex
@@ -465,10 +465,11 @@ defmodule IEx.Introspection do
 
   defp h_mod_fun_arity(mod, fun, arity) when is_atom(mod) do
     {language, format, docs} = get_docs(mod, [:function, :macro])
-    spec = get_spec(mod, fun, arity)
+    doc_tuple = find_doc_with_content(docs, fun, arity)
+    spec = get_spec(mod, fun, arity, doc_tuple)
 
     cond do
-      doc_tuple = find_doc_with_content(docs, fun, arity) ->
+      doc_tuple ->
         print_fun(mod, language, format, doc_tuple, spec)
         :ok
 
@@ -592,6 +593,22 @@ defmodule IEx.Introspection do
     |> Enum.find(&has_callback?(&1, fun, arity))
   end
 
+  defp get_spec(module, name, arity, doc_tuple) do
+    case get_spec(module, name, arity) do
+      [] ->
+        case doc_tuple do
+          {{_, ^name, doc_arity}, _, _, _, _} when doc_arity != arity ->
+            get_spec(module, name, doc_arity)
+
+          _ ->
+            []
+        end
+
+      spec ->
+        spec
+    end
+  end
+
   defp get_spec(module, name, arity) do
     with {:ok, all_specs} <- Typespec.fetch_specs(module),
          {_, specs} <- List.keyfind(all_specs, {name, arity}, 0) do
diff --git a/lib/iex/test/iex/helpers_test.exs b/lib/iex/test/iex/helpers_test.exs
index f2433c7925f..32628ebc291 100644
--- a/lib/iex/test/iex/helpers_test.exs
+++ b/lib/iex/test/iex/helpers_test.exs
@@ -515,6 +515,13 @@ defmodule IEx.HelpersTest do
       assert capture_io(fn -> h(def) end) =~ def_h
     end
 
+    test "prints spec for default arg function" do
+      spec = "@spec recompile([{:force, boolean()}]) :: :ok | :error | :noop"
+
+      assert capture_io(fn -> h(IEx.Helpers.recompile() / 0) end) =~ spec
+      assert capture_io(fn -> h(IEx.Helpers.recompile() / 1) end) =~ spec
+    end
+
     test "prints sigil documentation" do
       assert capture_io(fn -> h(~w//) end) =~ "Handles the sigil `~w` for list of words"
     end