ext: Updated Pybind11 to version 2.4.1.

This updates Pybind11 from version 2.2.1 to version 2.4.1. This fixes
warning/error received when "<experiment/optional>" is used when
compiling using c++14 with clang. It should be noted that
"ext/pybind11/include/pybind11/std.h" has been changed to include a fix
added by commit ba42457254cc362eddc099f22b60d469cc6369e0. This is
necessary to avoid build errors.

Built: Linux (gcc, c++11) and MacOS (clang, c++14).
Tested: Ran quick tests for X86, ARM, and RISC-V.
Deprecates: https://gem5-review.googlesource.com/c/public/gem5/+/21019
Change-Id: Ie9783511cb6be50136076a55330e645f4f36d075
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21119
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/ext/pybind11/tests/test_union.cpp b/ext/pybind11/tests/test_union.cpp
new file mode 100644
index 000000000..7b98ea216
--- /dev/null
+++ b/ext/pybind11/tests/test_union.cpp
@@ -0,0 +1,22 @@
+/*
+    tests/test_class.cpp -- test py::class_ definitions and basic functionality
+
+    Copyright (c) 2019 Roland Dreier <roland.dreier@gmail.com>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#include "pybind11_tests.h"
+
+TEST_SUBMODULE(union_, m) {
+    union TestUnion {
+        int value_int;
+        unsigned value_uint;
+    };
+
+    py::class_<TestUnion>(m, "TestUnion")
+        .def(py::init<>())
+        .def_readonly("as_int", &TestUnion::value_int)
+        .def_readwrite("as_uint", &TestUnion::value_uint);
+}