Deterministic struct expansion (#12418)

Author: sabiwara

lib/elixir/lib/module/types.ex

@@ -252,7 +252,7 @@ defmodule Module.Types do
         "undefined field \"#{atom}\" ",
         format_expr(expr, location),
         "expected one of the following fields: ",
-        Enum.map_join(Enum.sort(known_atoms), ", ", & &1),
+        Enum.join(Enum.sort(known_atoms), ", "),
         "\n\n",
         traces,
         format_message_hints(hints),

lib/elixir/src/elixir_map.erl

@@ -25,7 +25,7 @@ expand_struct(Meta, Left, {'%{}', MapMeta, MapArgs}, S, #{context := Context} =
           AssocKeys = [K || {K, _} <- Assocs],
           Struct = load_struct(Meta, ELeft, [Assocs], AssocKeys, EE),
           Keys = ['__struct__'] ++ AssocKeys,
-          WithoutKeys = maps:to_list(maps:without(Keys, Struct)),
+          WithoutKeys = lists:sort(maps:to_list(maps:without(Keys, Struct))),
           StructAssocs = elixir_quote:escape(WithoutKeys, none, false),
           {{'%', Meta, [ELeft, {'%{}', MapMeta, StructAssocs ++ Assocs}]}, SE, EE};
 

lib/elixir/test/elixir/module/types/pattern_test.exs

@@ -140,25 +140,25 @@ defmodule Module.Types.PatternTest do
     end
 
     test "struct" do
-      assert quoted_pattern(%:"Elixir.Module.Types.PatternTest.Struct"{}) ==
-               {:ok,
-                {:map,
-                 [
-                   {:required, {:atom, :__struct__}, {:atom, Module.Types.PatternTest.Struct}},
-                   {:required, {:atom, :bar}, :dynamic},
-                   {:required, {:atom, :baz}, :dynamic},
-                   {:required, {:atom, :foo}, :dynamic}
-                 ]}}
-
-      assert quoted_pattern(%:"Elixir.Module.Types.PatternTest.Struct"{foo: 123, bar: :atom}) ==
-               {:ok,
-                {:map,
-                 [
-                   {:required, {:atom, :foo}, :integer},
-                   {:required, {:atom, :bar}, {:atom, :atom}},
-                   {:required, {:atom, :__struct__}, {:atom, Module.Types.PatternTest.Struct}},
-                   {:required, {:atom, :baz}, :dynamic}
-                 ]}}
+      assert {:ok, {:map, fields}} = quoted_pattern(%:"Elixir.Module.Types.PatternTest.Struct"{})
+
+      assert Enum.sort(fields) == [
+               {:required, {:atom, :__struct__}, {:atom, Module.Types.PatternTest.Struct}},
+               {:required, {:atom, :bar}, :dynamic},
+               {:required, {:atom, :baz}, :dynamic},
+               {:required, {:atom, :foo}, :dynamic}
+             ]
+
+      assert {:ok, {:map, fields}} =
+               quoted_pattern(%:"Elixir.Module.Types.PatternTest.Struct"{foo: 123, bar: :atom})
+
+      assert Enum.sort(fields) ==
+               [
+                 {:required, {:atom, :__struct__}, {:atom, Module.Types.PatternTest.Struct}},
+                 {:required, {:atom, :bar}, {:atom, :atom}},
+                 {:required, {:atom, :baz}, :dynamic},
+                 {:required, {:atom, :foo}, :integer}
+               ]
     end
 
     test "struct var" do