From c23302a5d7f0f58925d817282185d4b849763d9e Mon Sep 17 00:00:00 2001
From: Wojtek Mach <wojtek@wojtekmach.pl>
Date: Mon, 12 Oct 2020 18:19:58 +0200
Subject: [PATCH] Don't crash on code blocks like "A.b.C", closes #1285

---
 lib/ex_doc/autolink.ex        | 15 ++++++++++++---
 test/ex_doc/autolink_test.exs |  1 +
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/lib/ex_doc/autolink.ex b/lib/ex_doc/autolink.ex
index b31943078..047017270 100644
--- a/lib/ex_doc/autolink.ex
+++ b/lib/ex_doc/autolink.ex
@@ -288,9 +288,18 @@ defmodule ExDoc.Autolink do
 
   defp do_parse_module(string) do
     case Code.string_to_quoted(string, warn_on_unnecessary_quotes: false) do
-      {:ok, module} when is_atom(module) -> {:module, module}
-      {:ok, {:__aliases__, _, parts}} -> {:module, Module.concat(parts)}
-      _ -> :error
+      {:ok, module} when is_atom(module) ->
+        {:module, module}
+
+      {:ok, {:__aliases__, _, parts}} ->
+        if Enum.all?(parts, &is_atom/1) do
+          {:module, Module.concat(parts)}
+        else
+          :error
+        end
+
+      _ ->
+        :error
     end
   end
 
diff --git a/test/ex_doc/autolink_test.exs b/test/ex_doc/autolink_test.exs
index 0606031f3..3773f1706 100644
--- a/test/ex_doc/autolink_test.exs
+++ b/test/ex_doc/autolink_test.exs
@@ -33,6 +33,7 @@ defmodule ExDoc.AutolinkTest do
     test "unknown module" do
       assert_unchanged("Unknown")
       assert_unchanged(":unknown")
+      assert_unchanged("A.b.C")
     end
 
     test "project-local module" do