Move tv::none into its own module

Author: davidstone

CMakeLists.txt

@@ -179,6 +179,7 @@ target_sources(tv PUBLIC
 		source/tv/indexed_value.cpp
 		source/tv/insert.cpp
 		source/tv/is_valid_index.cpp
+		source/tv/none.cpp
 		source/tv/nth_type.cpp
 		source/tv/optional.cpp
 		source/tv/overload.cpp

source/tv/none.cpp

@@ -0,0 +1,16 @@
+// Copyright David Stone 2023.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+export module tv.none;
+ 
+namespace tv {
+
+// none_t cannot be default constructible or we get an ambiguity in op = {};
+export struct none_t {
+	constexpr explicit none_t(int) {}
+};
+export constexpr auto none = none_t(0);
+
+} // namespace tv

source/tv/optional.cpp

@@ -16,6 +16,7 @@ module;
 export module tv.optional;
 
 import tv.insert;
+import tv.none;
 import tv.variant;
 
 import bounded;
@@ -27,12 +28,6 @@ using namespace bounded::literal;
 
 namespace tv {
 
-// none_t cannot be default constructible or we get an ambiguity in op = {};
-export struct none_t {
-	constexpr explicit none_t(int) {}
-};
-export constexpr auto none = none_t(0);
-
 template<typename T>
 struct optional_storage {
 	constexpr optional_storage():

source/tv/tv.cpp

@@ -7,6 +7,7 @@ export module tv;
 
 export import tv.indexed_value;
 export import tv.insert;
+export import tv.none;
 export import tv.optional;
 export import tv.overload;
 export import tv.single_element_storage;