Added futurecpp.h

CMakeLists.txt

@@ -3,6 +3,7 @@ set(headers
     src/espcrc32builder.h
     src/esprandom.h
     src/espstrutils.h
+    src/futurecpp.h
     src/lockhelper.h
     src/lockingqueue.h
     src/recursivelockhelper.h

src/futurecpp.h

@@ -0,0 +1,29 @@
+#pragma once
+
+// system includes
+#include <cstring>
+#include <limits>
+
+// C++20 backports (until espressif finally updates their aged compiler suite)
+
+namespace std {
+template <class To, class From>
+typename std::enable_if_t<
+    sizeof(To) == sizeof(From) && std::is_trivially_copyable_v<From> && std::is_trivially_copyable_v<To>,
+    To>
+// constexpr support needs compiler magic
+bit_cast(const From& src) noexcept
+{
+    static_assert(std::is_trivially_constructible_v<To>,
+                  "This implementation additionally requires destination type to be trivially constructible");
+
+    To dst;
+    std::memcpy(&dst, &src, sizeof(To));
+    return dst;
+}
+
+template <typename EnumT, typename = std::enable_if_t<std::is_enum<EnumT>{}>>
+constexpr std::underlying_type_t<EnumT> to_underlying(EnumT e) noexcept {
+    return static_cast<std::underlying_type_t<EnumT>>(e);
+}
+} // namespace std