Add C++ modules support and update nlohmann::json

Author: mikomikotaishi

CMakeLists.txt

@@ -18,7 +18,7 @@
 
 cmake_minimum_required (VERSION 3.16)
 set(CMAKE_CXX_STANDARD 17)
- 
+
 option(BUILD_SHARED_LIBS "Build shared libraries" ON)
 option(BUILD_VOICE_SUPPORT "Build voice support" ON)
 option(RUN_LDCONFIG "Run ldconfig after installation" ON)
@@ -33,6 +33,7 @@ option(DPP_USE_EXTERNAL_JSON "Use an external installation of nlohmann::json" OF
 option(DPP_USE_PCH "Use precompiled headers to speed up compilation" OFF)
 option(AVX_TYPE "Force AVX type for speeding up audio mixing" OFF)
 option(DPP_TEST_VCPKG "Force VCPKG build without VCPKG installed (for development use only!)" OFF)
+option(DPP_MODULES "Support for C++20 modules" OFF)
 
 include(CheckCXXSymbolExists)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
@@ -159,3 +160,12 @@ endif()
 if (NOT WIN32)
 	target_link_libraries(dpp PRIVATE std::filesystem)
 endif()
+
+if (DPP_MODULES)
+	add_subdirectory(src/modules)
+	target_compile_definitions(dpp PUBLIC DPP_MODULES)
+	message("-- C++20 Modules support: ${Green}ENABLED${ColourReset}")
+else()
+	message("-- C++20 Modules support: ${Red}DISABLED${ColourReset} (enable with -DDPP_MODULES=ON)")
+endif()
+

README.md

@@ -33,6 +33,7 @@ D++ is a lightweight and efficient library for **Discord** written in **modern C
 * Stable [Windows support](https://dpp.dev/buildwindows.html)
 * Ready-made compiled packages for Windows, Raspberry Pi (ARM64/ARM7/ARMv6), Debian x86/x64, and RPM based distributions
 * Highly scalable for large amounts of guilds and users
+* Support for C++ modules
 
 Want to help? Drop me a line or send a PR.
 

docpages/example_code/CMakeLists.txt

@@ -33,7 +33,7 @@ project(documentation_tests)
 
 string(ASCII 27 Esc)
 
-set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DDPP_CORO -std=c++20 -pthread -O0 -fPIC -rdynamic -DFMT_HEADER_ONLY -Wall -Wextra -Wpedantic -Werror -Wno-unused-parameter -Wno-deprecated-declarations")
+set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DDPP_CORO -DPP_MODULES -std=c++20 -pthread -O0 -fPIC -rdynamic -DFMT_HEADER_ONLY -Wall -Wextra -Wpedantic -Werror -Wno-unused-parameter -Wno-deprecated-declarations")
 set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0")
 
 file(GLOB example_list ./*.cpp)

docpages/example_code/using_modules.cpp

@@ -0,0 +1,29 @@
+/* If import std; is supported, use it instead */
+#include <cstdlib>
+
+import dpp;
+
+using dpp::cluster;
+using dpp::slashcommand;
+using dpp::start_type;
+
+int main() {
+	cluster bot(std::getenv("BOT_TOKEN"));
+
+	bot.on_slashcommand([](auto event) {
+		if (event.command.get_command_name() == "ping") {
+			event.reply("Pong!");
+		}
+	});
+
+	bot.on_ready([&bot](auto event) {
+		if (dpp::run_once<struct register_bot_commands>()) {
+			bot.global_command_create(
+				slashcommand("ping", "Ping pong!", bot.me.id)
+			);
+		}
+	});
+
+	bot.start(start_type::st_wait);
+	return 0;
+}

docpages/example_programs/misc.md

@@ -13,3 +13,4 @@ This section lists examples that do not fit neatly into any of the categories ab
 * \subpage setting_status
 * \subpage using-emojis
 * \subpage using_timers
+* \subpage using_modules

docpages/example_programs/misc/using_modules.md

@@ -0,0 +1,9 @@
+\page using_modules Using D++ with C++ modules
+
+D++ is offered as a C++ module, which offers improved compile times over a traditional header.
+
+In order to enable support, you should be using C++20+ with any module-supporting compiler. To activate the feature, pass the `DPP_MODULES` flag to CMake. Ensure that the generated build system supports modules (for CMake, this is usually Ninja).
+
+Once this is done, simply `import dpp;` and we're good to go!
+
+\include{cpp} using_modules.cpp

include/dpp/cluster.h

@@ -58,7 +58,7 @@ namespace dpp {
  * requests to Discord. This is useful for bots that do not need to receive websocket events as it will save a lot of
  * resources.
  */
-constexpr uint32_t NO_SHARDS = ~0U;
+inline constexpr uint32_t NO_SHARDS = ~0U;
 
 /**
  * @brief Types of startup for cluster::start()

include/dpp/colors.h

@@ -31,7 +31,7 @@ namespace dpp {
  * @brief predefined color constants.
  */
 namespace colors {
-	static constexpr uint32_t
+	inline constexpr uint32_t
 		white = 0xFFFFFF,
 		discord_white = 0xFFFFFE,
 		light_gray = 0xC0C0C0,

include/dpp/discordclient.h

@@ -57,7 +57,7 @@ class cluster;
  * @brief How many seconds to wait between (re)connections. DO NOT change this.
  * It is mandated by the Discord API spec!
  */
-constexpr time_t RECONNECT_INTERVAL = 5;
+inline constexpr time_t RECONNECT_INTERVAL = 5;
 
 /**
  * @brief Represents different event opcodes sent and received on a shard websocket

include/dpp/etf.h

@@ -42,7 +42,7 @@ namespace dpp {
 /**
  * @brief Current ETF format version in use
  */
-const uint8_t FORMAT_VERSION = 131;
+inline const uint8_t FORMAT_VERSION = 131;
 
 /**
  * @brief Represents a token which identifies the type of value which follows it