From 237a71311c5ae4fc5dd3c7a590a7b6dab97a664a Mon Sep 17 00:00:00 2001
From: Wojtek Mach <wojtekmach@users.noreply.github.com>
Date: Tue, 23 Mar 2021 17:40:04 +0100
Subject: [PATCH 2/3] Update warnings for OTP master (#10807)

---
 lib/elixir/src/elixir_erl_compiler.erl        | 34 ++++++++++++-------
 .../test/elixir/kernel/warning_test.exs       | 25 --------------
 2 files changed, 21 insertions(+), 38 deletions(-)

diff --git a/lib/elixir/src/elixir_erl_compiler.erl b/lib/elixir/src/elixir_erl_compiler.erl
index 7010b59fd..e0aa05114 100644
--- a/lib/elixir/src/elixir_erl_compiler.erl
+++ b/lib/elixir/src/elixir_erl_compiler.erl
@@ -94,6 +94,8 @@ handle_file_warning(true, _File, {_Line, sys_core_fold, {nomatch_shadow, _}}) ->
 
 %% Those we implement ourselves
 handle_file_warning(_, _File, {_Line, v3_core, {map_key_repeated, _}}) -> ok;
+handle_file_warning(_, _File, {_Line, sys_core_fold, {ignored, useless_building}}) -> ok;
+%% TODO: remove when we require Erlang/OTP 24
 handle_file_warning(_, _File, {_Line, sys_core_fold, useless_building}) -> ok;
 
 %% Ignore all linting errors (only come up on parse transforms)
@@ -112,11 +114,11 @@ handle_file_error(File, {Line, Module, Desc}) ->
   elixir_errors:compile_error([{line, Line}], File, Message).
 
 %% Mention the capture operator in make_fun
-custom_format(sys_core_fold, {no_effect, {erlang, make_fun, 3}}) ->
+custom_format(sys_core_fold, {ignored, {no_effect, {erlang, make_fun, 3}}}) ->
   "the result of the capture operator & (:erlang.make_fun/3) is never used";
 
 %% Make no_effect clauses pretty
-custom_format(sys_core_fold, {no_effect, {erlang, F, A}}) ->
+custom_format(sys_core_fold, {ignored, {no_effect, {erlang, F, A}}}) ->
   {Fmt, Args} = case erl_internal:comp_op(F, A) of
     true -> {"use of operator ~ts has no effect", [elixir_utils:erlang_comparison_op_to_elixir(F)]};
     false ->
@@ -127,12 +129,20 @@ custom_format(sys_core_fold, {no_effect, {erlang, F, A}}) ->
   end,
   io_lib:format(Fmt, Args);
 
-%% Rewrite nomatch_guard to be more generic it can happen inside if, unless, and the like
-custom_format(sys_core_fold, nomatch_guard) ->
+%% Rewrite nomatch to be more generic, it can happen inside if, unless, and the like
+custom_format(sys_core_fold, {nomatch, X}) when X == guard; X == no_clause ->
   "this check/guard will always yield the same result";
 
+custom_format(sys_core_fold, {nomatch, {shadow, Line, {ErlName, ErlArity}}}) ->
+  {Name, Arity} = elixir_utils:erl_fa_to_elixir_fa(ErlName, ErlArity),
+
+  io_lib:format(
+    "this clause for ~ts/~B cannot match because a previous clause at line ~B always matches",
+    [Name, Arity, Line]
+  );
+
 %% Handle literal eval failures
-custom_format(sys_core_fold, {eval_failure, {Mod, Name, Arity}, Error}) ->
+custom_format(sys_core_fold, {failed, {eval_failure, {Mod, Name, Arity}, Error}}) ->
   #{'__struct__' := Struct} = 'Elixir.Exception':normalize(error, Error),
   {ExMod, ExName, ExArgs} = elixir_rewrite:erl_to_ex(Mod, Name, lists:duplicate(Arity, nil)),
   Call = 'Elixir.Exception':format_mfa(ExMod, ExName, length(ExArgs)),
@@ -143,18 +153,16 @@ custom_format(sys_core_fold, {eval_failure, {Mod, Name, Arity}, Error}) ->
   ["the call to ", Trimmed, " will fail with ", elixir_aliases:inspect(Struct)];
 
 %% TODO: remove when we require OTP 24
+custom_format(sys_core_fold, {nomatch_shadow, Line, FA}) ->
+  custom_format(sys_core_fold, {nomatch, {shadow, Line, FA}});
+custom_format(sys_core_fold, nomatch_guard) ->
+  custom_format(sys_core_fold, {nomatch, guard});
+custom_format(sys_core_fold, {no_effect, X}) ->
+  custom_format(sys_core_fold, {ignored, {no_effect, X}});
 custom_format(sys_core_fold, {eval_failure, Error}) ->
   #{'__struct__' := Struct} = 'Elixir.Exception':normalize(error, Error),
   ["this expression will fail with ", elixir_aliases:inspect(Struct)];
 
-custom_format(sys_core_fold, {nomatch_shadow,Line,{ErlName,ErlArity}}) ->
-  {Name, Arity} = elixir_utils:erl_fa_to_elixir_fa(ErlName, ErlArity),
-
-  io_lib:format(
-    "this clause for ~ts/~B cannot match because a previous clause at line ~B always matches",
-    [Name, Arity, Line]
-  );
-
 custom_format([], Desc) ->
   io_lib:format("~p", [Desc]);
 
diff --git a/lib/elixir/test/elixir/kernel/warning_test.exs b/lib/elixir/test/elixir/kernel/warning_test.exs
index 15a984a54..37334ff65 100644
--- a/lib/elixir/test/elixir/kernel/warning_test.exs
+++ b/lib/elixir/test/elixir/kernel/warning_test.exs
@@ -1154,31 +1154,6 @@ def foo(x), do: :ok
     purge(Sample)
   end
 
-  test "with and do clauses emit errors, else clauses do not" do
-    assert capture_err(fn ->
-             Code.compile_string("""
-             with {:first, int} when is_integer(int) <- {:second, Integer.gcd(2, 4)} do
-               int
-             end
-             """)
-           end) =~ "this clause cannot match"
-
-    assert capture_err(fn ->
-             Code.compile_string("""
-             with {:first, int1} when is_integer(int1) <- {:first, Integer.gcd(2, 4)},
-                  {:second, int2} when is_integer(int2) <- {:second, Integer.gcd(2, 4)} do
-               {:ok, int1 + int2}
-             else
-               {:first, nil} -> {:error, "first number is not integer"}
-               {:second, nil} -> {:error, "second number is not integer"}
-             end
-             """)
-           end) == ""
-  after
-    purge(Sample1)
-    purge(Sample2)
-  end
-
   test "warning on code point escape" do
     assert capture_err(fn ->
              Code.eval_string("? ")
-- 
2.31.1