Attempts to solve #13593

Attempts to solve an issue that causes `Macro.escape/2` to crash when
given certain tuples.

Note that, `Macro.escape({:quote, [column: 10], [:foo]})` still produces
: `{:{}, [], [:quote, [], [:foo]]}` which is arguably wrong.

Author: kristofka

lib/elixir/src/elixir_quote.erl

@@ -538,8 +538,10 @@ update_last([H | T], F) -> [H | update_last(T, F)].
 
 keyfind(Key, Meta) ->
   lists:keyfind(Key, 1, Meta).
-keydelete(Key, Meta) ->
-  lists:keydelete(Key, 1, Meta).
+keydelete(Key, Meta) when is_list(Meta) ->
+  lists:keydelete(Key, 1, Meta);
+keydelete(_Key, Meta) ->
+  Meta.
 keystore(_Key, Meta, nil) ->
   Meta;
 keystore(Key, Meta, Value) ->
@@ -571,4 +573,4 @@ annotate_def({'when', Meta, [Left, Right]}, Context) ->
 annotate_def({Fun, Meta, Args}, Context) ->
   {Fun, keystore(context, Meta, Context), Args};
 annotate_def(Other, _Context) ->
-  Other.
+  Other.

lib/elixir/test/elixir/macro_test.exs

@@ -38,6 +38,11 @@ defmodule MacroTest do
       assert Macro.escape({:a, {1, 2, 3}, :c}) == {:{}, [], [:a, {:{}, [], [1, 2, 3]}, :c]}
     end
 
+    test "correctly escapes tuples where the first element is :quote" do
+      assert Macro.escape({:quote, :foo, [:bar]}) == {:{}, [], [:quote, :foo, [:bar]]}
+      assert Macro.escape({:quote, :foo, [:bar, :baz]}) == {:{}, [], [:quote, :foo, [:bar, :baz]]}
+    end
+
     test "escapes maps" do
       assert Macro.escape(%{a: 1}) == {:%{}, [], [a: 1]}
     end