Discard warnings from refinemenets

Author: josevalim

lib/elixir/lib/module/types/expr.ex

@@ -353,10 +353,10 @@ defmodule Module.Types.Expr do
     of_body = fn trees, body, context ->
       [arg_type] = Pattern.of_domain(trees, stack, context)
 
-      {_, context} =
+      {_, refined_context} =
         of_expr(case_expr, arg_type, case_expr, %{stack | reverse_arrow: :use}, context)
 
-      of_expr(body, expected, body, stack, context)
+      of_expr(body, expected, body, stack, reset_warnings(refined_context, context))
     end
 
     result_context =
@@ -804,6 +804,8 @@ defmodule Module.Types.Expr do
     {result, context}
   end
 
+  defp reset_warnings(context, %{warnings: warnings}), do: %{context | warnings: warnings}
+
   defp reset_failed(%{failed: true} = context, false), do: {true, %{context | failed: false}}
   defp reset_failed(context, _), do: {false, context}
 

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

@@ -1931,6 +1931,17 @@ defmodule Module.Types.ExprTest do
                )
     end
 
+    test "discards warnings from refinements" do
+      assert {_, [_]} =
+               typediag!(
+                 if x = System.unknown_function_get_env("HELLO") do
+                   {:ok, x}
+                 else
+                   {:error, x}
+                 end
+               )
+    end
+
     test "and/or does not report on literals" do
       assert typecheck!(false and true) == boolean()
       assert typecheck!(false or true) == atom([true])

lib/mix/lib/mix/compilers/elixir.ex

@@ -5,7 +5,7 @@
 defmodule Mix.Compilers.Elixir do
   @moduledoc false
 
-  @manifest_vsn 33
+  @manifest_vsn 34
   @checkpoint_vsn 4
 
   import Record