Show list opts when inspecting Regex

lib/elixir/lib/inspect.ex

@@ -381,6 +381,16 @@ defimpl Inspect, for: Float do
 end
 
 defimpl Inspect, for: Regex do
+  def inspect(regex = %{opts: regex_opts}, opts) when is_list(regex_opts) do
+    concat([
+      "Regex.compile!(",
+      Inspect.BitString.inspect(regex.source, opts),
+      ", ",
+      Inspect.List.inspect(regex_opts, opts),
+      ")"
+    ])
+  end
+
   def inspect(regex, opts) do
     {escaped, _} =
       regex.source

lib/elixir/lib/regex.ex

@@ -155,7 +155,7 @@ defmodule Regex do
 
   defstruct re_pattern: nil, source: "", opts: "", re_version: ""
 
-  @type t :: %__MODULE__{re_pattern: term, source: binary, opts: binary}
+  @type t :: %__MODULE__{re_pattern: term, source: binary, opts: binary | list(atom)}
 
   defmodule CompileError do
     defexception message: "regex could not be compiled"
@@ -203,13 +203,18 @@ defmodule Regex do
   defp compile(source, opts, doc_opts, version) do
     case :re.compile(source, opts) do
       {:ok, re_pattern} ->
+        doc_opts = format_doc_opts(doc_opts, opts)
         {:ok, %Regex{re_pattern: re_pattern, re_version: version, source: source, opts: doc_opts}}
 
       error ->
         error
     end
   end
 
+  defp format_doc_opts(_doc_opts = "", _opts = []), do: ""
+  defp format_doc_opts(_doc_opts = "", opts), do: opts
+  defp format_doc_opts(doc_opts, _opts), do: doc_opts
+
   @doc """
   Compiles the regular expression and raises `Regex.CompileError` in case of errors.
   """

lib/elixir/test/elixir/inspect_test.exs

@@ -863,6 +863,8 @@ defmodule Inspect.OthersTest do
     assert inspect(~r<\a\b\d\e\f\n\r\s\t\v/>) == "~r/\\a\\b\\d\\e\\f\\n\\r\\s\\t\\v\\//"
     assert inspect(~r" \\/ ") == "~r/ \\\\\\/ /"
     assert inspect(~r/hi/, syntax_colors: [regex: :red]) == "\e[31m~r/hi/\e[0m"
+
+    assert inspect(Regex.compile!("foo", [:caseless])) == ~S'Regex.compile!("foo", [:caseless])'
   end
 
   test "inspect_fun" do