Skip autocompletion of module names that are invalid without being quoted (#6080)

2 files changed, 26 insertions, 3 deletions

diff --git a/lib/iex/lib/iex/autocomplete.ex b/lib/iex/lib/iex/autocomplete.ex
index 626e307b0..b3d823653 100644
--- a/lib/iex/lib/iex/autocomplete.ex
+++ b/lib/iex/lib/iex/autocomplete.ex
@@ -173,7 +173,8 @@ defmodule IEx.Autocomplete do
   end
 
   defp match_erlang_modules(hint) do
-    for mod <- match_modules(hint, true) do
+    for mod <- match_modules(hint, true),
+        usable_as_unquoted_atom?(mod) do
       %{kind: :module, name: mod, type: :erlang}
     end
   end
@@ -225,14 +226,20 @@ defmodule IEx.Autocomplete do
 
     for mod <- match_modules(base, module === Elixir),
         parts = String.split(mod, "."),
-        depth <= length(parts) do
-      %{kind: :module, type: :elixir, name: Enum.at(parts, depth - 1)}
+        depth <= length(parts),
+        name = Enum.at(parts, depth - 1),
+        usable_as_unquoted_atom?("Elixir." <> name) do
+      %{kind: :module, type: :elixir, name: name}
     end
     |> Enum.uniq
   end
 
   ## Helpers
 
+  defp usable_as_unquoted_atom?(name) do
+    not String.starts_with?(inspect(String.to_atom(name)), ":\"")
+  end
+
   defp match_modules(hint, root) do
     get_modules(root)
     |> :lists.usort()
diff --git a/lib/iex/test/iex/autocomplete_test.exs b/lib/iex/test/iex/autocomplete_test.exs
index 81f39f8da..bbf119e8d 100644
--- a/lib/iex/test/iex/autocomplete_test.exs
+++ b/lib/iex/test/iex/autocomplete_test.exs
@@ -285,4 +285,20 @@ defmodule IEx.AutocompleteTest do
     eval("struct = %IEx.AutocompleteTest.MyStruct{}")
     assert expand('struct.my') == {:yes, '_val', []}
   end
+
+  test "ignore invalid Elixir module literals" do
+    defmodule :"Elixir.IEx.AutocompleteTest.Unicodé", do: nil
+    assert expand('IEx.AutocompleteTest.Unicod') == {:no, '', []}
+  after
+    :code.purge(:"Elixir.IEx.AutocompleteTest.Unicodé")
+    :code.delete(:"Elixir.IEx.AutocompleteTest.Unicodé")
+  end
+
+  test "ignore invalid Erlang module literals" do
+    defmodule :"iex_autocomplete_unicodé", do: nil
+    assert expand(':iex_autocomplete_unicod') == {:no, '', []}
+  after
+    :code.purge(:"iex_autocomplete_unicodé")
+    :code.delete(:"iex_autocomplete_unicodé")
+  end
 end