Return value when matching with _ on last line of block

Closes #3125

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: oneeman

lib/elixir/src/elixir_translator.erl

@@ -10,7 +10,7 @@
 
 translate({'=', Meta, [Left, Right]}, S) ->
   Return = case Left of
-    {'_', _, Atom} when is_atom(Atom) -> false;
+    {'_', _, Atom} when is_atom(Atom) -> S#elixir_scope.return;
     _ -> true
   end,
 

lib/elixir/test/elixir/kernel/comprehension_test.exs

@@ -151,6 +151,12 @@ defmodule Kernel.ComprehensionTest do
     assert for({_,x} <- [1, 2, a: 3, b: 4, c: 5], do: x * 2) == [6, 8, 10]
   end
 
+  test "list for comprehension matched to '_' on last line of block" do
+    assert (if true do
+      _ = for x <- [1, 2, 3], do: x * 2
+    end) == [2, 4, 6]
+  end
+
   test "list for comprehensions with filters" do
     assert for(x <- [1, 2, 3], x > 1, x < 3, do: x * 2) == [4]
   end