Avoid capture operator warnings

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

Author: José Valim

lib/elixir/src/elixir_erl_compiler.erl

@@ -86,6 +86,10 @@ format_error(erl_lint, {undefined_function, {F, A}}) ->
 format_error(erl_lint, {spec_fun_undefined, {M, F, A}}) ->
   io_lib:format("spec for undefined function ~ts.~ts/~B", [elixir_aliases:inspect(M), F, A]);
 
+%% Mention the capture operator in make_fun
+format_error(sys_core_fold, {no_effect, {erlang, make_fun, 3}}) ->
+  "the result of the capture operator & (:erlang.make_fun/3) is never used";
+
 %% Make no_effect clauses pretty
 format_error(sys_core_fold, {no_effect, {erlang, F, A}}) ->
   {Fmt, Args} = case erl_internal:comp_op(F, A) of

lib/elixir/test/elixir/kernel/lexical_tracker_test.exs

@@ -234,21 +234,21 @@ defmodule Kernel.LexicalTrackerTest do
           NotAModule
           Remote.func()
           R.func()
-          &extract/2
-          &is_record/1
-          &R.func/0
-          &Remote.func/0
-          &Integer.is_even/1
+          _ = &extract/2
+          _ = &is_record/1
+          _ = &R.func/0
+          _ = &Remote.func/0
+          _ = &Integer.is_even/1
           %Macro.Env{}
         end
 
-        &extract/2
-        &is_record/1
-        &R.func/0
-        &Remote.func/0
-        &Integer.is_even/1
+        _ = &extract/2
+        _ = &is_record/1
+        _ = &R.func/0
+        _ = &Remote.func/0
+        _ = &Integer.is_even/1
 
-        &is_record/1; def b(a), do: is_record(a)
+        _ = &is_record/1; def b(a), do: is_record(a)
 
         %Macro.Env{}