Fix spec for Code.Identifier.escape/4 (#11445)

Closes #11444

3 files changed, 10 insertions, 9 deletions

diff --git a/lib/elixir/lib/code/identifier.ex b/lib/elixir/lib/code/identifier.ex
index 51f254558..8f60c69cc 100644
--- a/lib/elixir/lib/code/identifier.ex
+++ b/lib/elixir/lib/code/identifier.ex
@@ -214,10 +214,11 @@ defmodule Code.Identifier do
   @doc """
   Escapes the given identifier.
   """
-  @spec escape(binary(), char(), :infinity | non_neg_integer, (char() -> iolist() | false)) ::
+  @spec escape(binary(), char() | nil, :infinity | non_neg_integer, (char() -> iolist() | false)) ::
           {escaped :: iolist(), remaining :: binary()}
   def escape(binary, char, limit \\ :infinity, fun \\ &escape_map/1)
-      when limit == :infinity or (is_integer(limit) and limit >= 0) do
+      when ((char in 0..0x10FFFF or is_nil(char)) and limit == :infinity) or
+             (is_integer(limit) and limit >= 0) do
     escape(binary, char, limit, [], fun)
   end
 
diff --git a/lib/elixir/lib/code/normalizer.ex b/lib/elixir/lib/code/normalizer.ex
index c0a92dded..be455f274 100644
--- a/lib/elixir/lib/code/normalizer.ex
+++ b/lib/elixir/lib/code/normalizer.ex
@@ -277,7 +277,7 @@ defmodule Code.Normalizer do
       # It's a charlist
       list =
         if state.escape do
-          {string, _} = Code.Identifier.escape(IO.chardata_to_string(list), -1)
+          {string, _} = Code.Identifier.escape(IO.chardata_to_string(list), nil)
           IO.iodata_to_binary(string) |> to_charlist()
         else
           list
@@ -511,7 +511,7 @@ defmodule Code.Normalizer do
   end
 
   defp maybe_escape_literal(string, %{escape: true}) when is_binary(string) do
-    {string, _} = Code.Identifier.escape(string, -1)
+    {string, _} = Code.Identifier.escape(string, nil)
     IO.iodata_to_binary(string)
   end
 
diff --git a/lib/ex_unit/lib/ex_unit/diff.ex b/lib/ex_unit/lib/ex_unit/diff.ex
index 7656cfaf3..290ecaf3c 100644
--- a/lib/ex_unit/lib/ex_unit/diff.ex
+++ b/lib/ex_unit/lib/ex_unit/diff.ex
@@ -671,13 +671,13 @@ defmodule ExUnit.Diff do
          {:ok, inspect_left} <- safe_inspect(left),
          {:ok, inspect_right} <- safe_inspect(right) do
       if inspect_left != inspect_right do
-        diff_string(inspect_left, inspect_right, :none, env)
+        diff_string(inspect_left, inspect_right, nil, env)
       else
         # If they are equivalent, still use their inspected form
         case diff_map(kw, right, struct1, struct2, env) do
           {%{equivalent?: true}, ctx} ->
-            left = block_diff_container([inspect_left], :none)
-            right = block_diff_container([inspect_right], :none)
+            left = block_diff_container([inspect_left], nil)
+            right = block_diff_container([inspect_right], nil)
             {%__MODULE__{equivalent?: true, left: left, right: right}, ctx}
 
           diff_ctx ->
@@ -853,7 +853,7 @@ defmodule ExUnit.Diff do
     end
   end
 
-  defp block_diff_container(contents, :none),
+  defp block_diff_container(contents, nil),
     do: {:__block__, [], contents}
 
   defp block_diff_container(contents, container),
@@ -880,7 +880,7 @@ defmodule ExUnit.Diff do
   # Numbers
 
   defp diff_number(left, right, env) do
-    diff_string(inspect(left), inspect(right), :none, env)
+    diff_string(inspect(left), inspect(right), nil, env)
   end
 
   # Algebra