Handle non-binary bitstring in struct default values (elixir-lang#14363)

Author: sabiwara

lib/elixir/src/elixir_erl.erl

@@ -92,6 +92,9 @@ elixir_to_erl(Tree, Ann) when is_binary(Tree) ->
   %% considers a string in a binary to be encoded in latin1, so the bytes
   %% are not changed in any fashion.
   {bin, Ann, [{bin_element, Ann, {string, Ann, binary_to_list(Tree)}, default, default}]};
+elixir_to_erl(Tree, Ann) when is_bitstring(Tree) ->
+  Segments = [elixir_to_erl_bitstring_segment(X, Ann) || X <- bitstring_to_list(Tree)],
+  {bin, Ann, Segments};
 elixir_to_erl(Tree, Ann) when is_function(Tree) ->
   case (erlang:fun_info(Tree, type) == {type, external}) andalso
        (erlang:fun_info(Tree, env) == {env, []}) of
@@ -111,6 +114,13 @@ elixir_to_erl(Tree, Ann) ->
 elixir_to_erl_cons([H | T], Ann) -> {cons, Ann, elixir_to_erl(H, Ann), elixir_to_erl_cons(T, Ann)};
 elixir_to_erl_cons(T, Ann) -> elixir_to_erl(T, Ann).
 
+elixir_to_erl_bitstring_segment(Int, Ann) when is_integer(Int) ->
+  {bin_element, Ann, {integer, Ann, Int}, default, [integer]};
+elixir_to_erl_bitstring_segment(Rest, Ann) when is_bitstring(Rest) ->
+  Size = bit_size(Rest),
+  <<Int:Size>> = Rest,
+  {bin_element, Ann, {integer, Ann, Int}, {integer, Ann, Size}, [integer]}.
+
 %% Returns a scope for translation.
 
 scope(_Meta, ExpandCaptures) ->

lib/elixir/test/elixir/map_test.exs

@@ -395,6 +395,15 @@ defmodule MapTest do
     assert quoted == {:%, [], [User, {:%{}, [], [{:foo, 1}]}]}
   end
 
+  test "structs with bitstring defaults" do
+    defmodule WithBitstring do
+      defstruct bitstring: <<255, 127::7>>
+    end
+
+    info = Macro.struct_info!(WithBitstring, __ENV__)
+    assert info == [%{default: <<255, 127::7>>, field: :bitstring}]
+  end
+
   test "defstruct can only be used once in a module" do
     message =
       "defstruct has already been called for TestMod, " <>