Ensure &() works on blocks with one expressoin, closes #1704

Author: José Valim

lib/elixir/src/elixir_fn.erl

@@ -48,6 +48,9 @@ capture(Meta, { { '.', _, [_, Fun] }, _, Args } = Expr, S) when is_atom(Fun), is
 capture(Meta, { { '.', _, [_] }, _, Args } = Expr, S) when is_list(Args) ->
   do_capture(Meta, Expr, S, false);
 
+capture(Meta, { '__block__', _, [Expr] }, S) ->
+  capture(Meta, Expr, S);
+
 capture(Meta, { '__block__', _, _ } = Expr, S) ->
   Message = "invalid args for &, block expressions are not allowed, got: ~ts",
   syntax_error(Meta, S#elixir_scope.file, Message, ['Elixir.Macro':to_string(Expr)]);

lib/elixir/test/elixir/kernel/fn_test.exs

@@ -83,6 +83,10 @@ defmodule Kernel.FnTest do
     assert (&(&1.file(&2))).(__ENV__, "Hello").file == "Hello"
   end
 
+  test "capture block like" do
+    assert (&(!is_atom(&1))).(:foo) == false
+  end
+
   test "capture other" do
     assert (& &1).(:ok) == :ok