feat: Add C++ modules support

.github/workflows/ci.yml

@@ -272,3 +272,89 @@ jobs:
         with:
           name: "libdpp - RPM Package ${{matrix.cfg.name}}"
           path: "${{github.workspace}}/build/*.rpm"
+
+  # Static library build (BUILD_SHARED_LIBS=OFF)
+  static-linux:
+    permissions:
+      contents: read
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}-static-${{ matrix.cfg.cpp }}-${{ matrix.cfg.version }}
+      cancel-in-progress: true
+    name: Static Linux (${{ matrix.cfg.cpp }}-${{ matrix.cfg.version }})
+    runs-on: ${{ matrix.cfg.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        cfg:
+          - { os: ubuntu-24.04, package: g++-13, cpp: g++, version: 13, concurrency: 4 }
+          - { os: ubuntu-24.04, package: clang-20, cpp: clang++, version: 20, concurrency: 4 }
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
+        with:
+          egress-policy: audit
+
+      - name: Checkout D++
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+
+      - name: Setup mold
+        uses: rui314/setup-mold@9c9c13bf4c3f1adef0cc596abc155580bcb04444 # v1
+
+      - name: Install apt packages
+        run: sudo sed -i 's/azure\.//' /etc/apt/sources.list && sudo apt update && sudo apt-get install -y ${{ matrix.cfg.package }} pkg-config libopus-dev zlib1g-dev libssl-dev rpm
+
+      - name: Generate CMake
+        run: cmake -B build -DBUILD_SHARED_LIBS=OFF -DDPP_NO_VCPKG=ON -DAVX_TYPE=AVX0 -DCMAKE_BUILD_TYPE=Release
+        env:
+          CXX: ${{ matrix.cfg.cpp }}-${{ matrix.cfg.version }}
+
+      - name: Build Project
+        run: cd build && make -j${{ matrix.cfg.concurrency }}
+
+  # Install D++ and consume it from a separate project via find_package(dpp)
+  install-consumer:
+    permissions:
+      contents: read
+    name: Install & find_package(dpp)
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
+        with:
+          egress-policy: audit
+
+      - name: Checkout D++
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+
+      - name: Setup mold
+        uses: rui314/setup-mold@9c9c13bf4c3f1adef0cc596abc155580bcb04444 # v1
+
+      - name: Install apt packages
+        run: sudo sed -i 's/azure\.//' /etc/apt/sources.list && sudo apt update && sudo apt-get install -y g++-13 pkg-config libopus-dev zlib1g-dev libssl-dev
+
+      - name: Build and install D++
+        run: |
+          cmake -B build -DDPP_NO_VCPKG=ON -DAVX_TYPE=AVX0 -DCMAKE_BUILD_TYPE=Release -DDPP_BUILD_TEST=OFF -DCMAKE_INSTALL_PREFIX="$GITHUB_WORKSPACE/_install"
+          cmake --build build -j$(nproc)
+          cmake --install build
+        env:
+          CXX: g++-13
+
+      - name: Consume D++ via find_package
+        run: |
+          mkdir -p consumer && cd consumer
+          cat > CMakeLists.txt <<'EOF'
+          cmake_minimum_required(VERSION 3.16)
+          project(dpp_consumer CXX)
+          find_package(dpp REQUIRED)
+          add_executable(consumer main.cpp)
+          target_link_libraries(consumer dpp::dpp)
+          EOF
+          cat > main.cpp <<'EOF'
+          #include <dpp/dpp.h>
+          int main() { dpp::cluster bot("token"); return 0; }
+          EOF
+          cmake -B build -DCMAKE_PREFIX_PATH="$GITHUB_WORKSPACE/_install" -DCMAKE_BUILD_TYPE=Release
+          cmake --build build -j$(nproc)
+        env:
+          CXX: g++-13

.github/workflows/test-docs-examples.yml

@@ -18,7 +18,7 @@ permissions:
 jobs:
   test_docs_examples:
     name: Test build examples
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     concurrency:
       group: ${{ github.workflow }}-${{ github.ref }}
       cancel-in-progress: true
@@ -35,17 +35,19 @@ jobs:
           submodules: recursive
 
       - name: Install apt packages
-        run: sudo sed -i 's/azure\.//' /etc/apt/sources.list && sudo apt-get update && sudo apt-get install -y g++-12 libopus-dev zlib1g-dev libmpg123-dev liboggz-dev cmake libfmt-dev libopusfile-dev
+        run: sudo sed -i 's/azure\.//' /etc/apt/sources.list && sudo apt-get update && sudo apt-get install -y clang-20 libopus-dev ninja-build zlib1g-dev libmpg123-dev liboggz-dev cmake libfmt-dev libopusfile-dev
 
       - name: Generate CMake
-        run: mkdir build && cd build && cmake -DDPP_NO_VCPKG=ON -DAVX_TYPE=T_fallback -DDPP_CORO=ON -DCMAKE_BUILD_TYPE=Debug ..
+        run: mkdir build && cd build && cmake -G Ninja -DDPP_NO_VCPKG=ON -DDPP_MODULES=ON -DAVX_TYPE=T_fallback -DDPP_CORO=ON -DCMAKE_BUILD_TYPE=Debug ..
         env:
-          CXX: g++-12
+          CXX: clang++-20
 
       - name: Build Project
-        run: cd build && make -j2 && sudo make install
+        run: cd build && cmake --build . -j2 && sudo ninja install
+        env:
+          CXX: clang++-20
 
       - name: Test compile examples
-        run: cd docpages/example_code && mkdir build && cd build && cmake .. && make -j2
+        run: cd docpages/example_code && mkdir build && cd build && cmake -G Ninja -DDPP_MODULES=ON .. && cmake --build . -j2
         env:
-          CXX: g++-12
+          CXX: clang++-20

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 (experimental)" OFF)
 
 include(CheckCXXSymbolExists)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
@@ -159,3 +160,4 @@ endif()
 if (NOT WIN32)
 	target_link_libraries(dpp PRIVATE std::filesystem)
 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
+* Experimental support for [C++ modules](https://dpp.dev/using_modules.html)
 
 Want to help? Drop me a line or send a PR.
 

cmake/CPackSetup.cmake

@@ -11,20 +11,40 @@ set(DPP_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}/${DPP_VERSIONED})
 
 ## Pack the binary output
 if (WIN32)
-	install(TARGETS dpp
-		EXPORT ${DPP_EXPORT_NAME}
-		LIBRARY DESTINATION  ${DPP_INSTALL_LIBRARY_DIR}
-		ARCHIVE DESTINATION  ${DPP_INSTALL_LIBRARY_DIR}
-		RUNTIME DESTINATION  ${CMAKE_INSTALL_BINDIR}
-		INCLUDES DESTINATION ${DPP_INSTALL_INCLUDE_DIR})
+	if (DPP_MODULES)
+		install(TARGETS dpp
+			EXPORT ${DPP_EXPORT_NAME}
+			LIBRARY DESTINATION  ${DPP_INSTALL_LIBRARY_DIR}
+			ARCHIVE DESTINATION  ${DPP_INSTALL_LIBRARY_DIR}
+			RUNTIME DESTINATION  ${CMAKE_INSTALL_BINDIR}
+			INCLUDES DESTINATION ${DPP_INSTALL_INCLUDE_DIR}
+			FILE_SET CXX_MODULES DESTINATION ${DPP_INSTALL_INCLUDE_DIR})
+	else()
+		install(TARGETS dpp
+			EXPORT ${DPP_EXPORT_NAME}
+			LIBRARY DESTINATION  ${DPP_INSTALL_LIBRARY_DIR}
+			ARCHIVE DESTINATION  ${DPP_INSTALL_LIBRARY_DIR}
+			RUNTIME DESTINATION  ${CMAKE_INSTALL_BINDIR}
+			INCLUDES DESTINATION ${DPP_INSTALL_INCLUDE_DIR})
+	endif()
 	install(DIRECTORY "${DPP_ROOT_PATH}/include/" DESTINATION "${DPP_INSTALL_INCLUDE_DIR}")
 else()
-	install(TARGETS dpp
-		EXPORT ${DPP_EXPORT_NAME}
-		LIBRARY DESTINATION  ${CMAKE_INSTALL_LIBRARY_DIR}
-		ARCHIVE DESTINATION  ${CMAKE_INSTALL_LIBRARY_DIR}
-		RUNTIME DESTINATION  ${CMAKE_INSTALL_BINDIR}
-		INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDE_DIR})
+	if (DPP_MODULES)
+		install(TARGETS dpp
+			EXPORT ${DPP_EXPORT_NAME}
+			LIBRARY DESTINATION  ${CMAKE_INSTALL_LIBDIR}
+			ARCHIVE DESTINATION  ${CMAKE_INSTALL_LIBDIR}
+			RUNTIME DESTINATION  ${CMAKE_INSTALL_BINDIR}
+			INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+			FILE_SET CXX_MODULES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+	else()
+		install(TARGETS dpp
+			EXPORT ${DPP_EXPORT_NAME}
+			LIBRARY DESTINATION  ${CMAKE_INSTALL_LIBDIR}
+			ARCHIVE DESTINATION  ${CMAKE_INSTALL_LIBDIR}
+			RUNTIME DESTINATION  ${CMAKE_INSTALL_BINDIR}
+			INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+	endif()
 endif()
 
 ## Allow for a specific version to be chosen in the `find_package` command

docpages/example_code/CMakeLists.txt

@@ -28,19 +28,43 @@
 # libmpg123-dev
 # dpp latest master with -DDPP_CORO=ON installed sytemwide
 
-cmake_minimum_required (VERSION 3.16)
+cmake_minimum_required (VERSION 3.28)
 project(documentation_tests)
 
 include("${CMAKE_CURRENT_SOURCE_DIR}/../../cmake/colour.cmake")
 
-set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DDPP_CORO -std=c++20 -pthread -O0 -fPIC -rdynamic -DFMT_HEADER_ONLY -Wall -Wextra -Wpedantic -Werror -Wno-unused-parameter -Wno-deprecated-declarations")
+option(DPP_MODULES "Build examples with C++20 modules support" ON)
+
+set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DDPP_CORO -std=c++20 -pthread -O0 -fPIC -DFMT_HEADER_ONLY -Wall -Wextra -Wpedantic -Werror -Wno-unused-parameter -Wno-deprecated-declarations")
 set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0")
 
+set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -rdynamic")
+
+# Create gcm.cache directory and symlink to the main build's dpp.gcm
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+	file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/gcm.cache")
+	file(CREATE_LINK "${CMAKE_SOURCE_DIR}/../../build/library/CMakeFiles/dpp.dir/dpp.gcm"
+		"${CMAKE_BINARY_DIR}/gcm.cache/dpp.gcm" SYMBOLIC)
+endif()
+
 file(GLOB example_list ./*.cpp)
 foreach (example ${example_list})
 	get_filename_component(examplename ${example} NAME)
 	message(STATUS "Found example '${BoldBlue}${examplename}${ColourReset}'")
 	add_executable(${examplename}_out ${example})
 	target_link_libraries(${examplename}_out dl dpp mpg123 oggz ogg opusfile opus)
 	include_directories(/usr/include/opus)
+
+	target_compile_definitions(${examplename}_out PRIVATE DPP_MODULES)
+	set_target_properties(${examplename}_out PROPERTIES CXX_SCAN_FOR_MODULES ON)
+
+	if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+		target_compile_options(${examplename}_out PRIVATE -fmodules-ts)
+	elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+		target_compile_options(${examplename}_out PRIVATE 
+			-fmodules
+			-mavx2
+			-fprebuilt-module-path=${CMAKE_SOURCE_DIR}/../../build/library/CMakeFiles/dpp.dir
+		)
+	endif()
 endforeach(example)

docpages/example_code/using_modules.cpp

@@ -0,0 +1,25 @@
+#include <string>
+#include <typeinfo>
+
+import dpp;
+
+int main() {
+	dpp::cluster bot("YOUR_BOT_TOKEN_HERE");
+
+	bot.on_slashcommand([](const dpp::slashcommand_t& event) -> void {
+		if (event.command.get_command_name() == "ping") {
+			event.reply("Pong!");
+		}
+	});
+
+	bot.on_ready([&bot](const dpp::ready_t& event) -> void {
+		if (dpp::run_once<struct register_bot_commands>()) {
+			bot.global_command_create(
+				dpp::slashcommand("ping", "Ping pong!", bot.me.id)
+			);
+		}
+	});
+
+	bot.start(dpp::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 must use C++20 (or later) 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; note CMake does not currently support modules with Makefile).
+
+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/dpp.cppm

@@ -0,0 +1,67 @@
+/************************************************************************************
+ *
+ * D++, A Lightweight C++ library for Discord
+ *
+ * Copyright 2021 Craig Edwards and D++ contributors
+ * (https://github.com/brainboxdotcc/DPP/graphs/contributors)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ ************************************************************************************/
+
+module;
+
+// Include the entire standard library so it doesn't cause issue in our headers
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <ctime>
+
+#include <algorithm>
+#include <charconv>
+#include <condition_variable>
+#include <cstddef>
+#include <ctime>
+#include <deque>
+#include <exception>
+#include <fstream>
+#include <functional>
+#include <iomanip>
+#include <iostream>
+#include <locale>
+#include <map>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <queue>
+#include <shared_mutex>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <thread>
+#include <type_traits>
+#include <unordered_map>
+#include <variant>
+#include <vector>
+
+#include <dpp/export.h>
+#include <dpp/compat.h>
+
+export module dpp;
+
+export extern "C++" {
+    #include <dpp/dpp.h>
+    #include <dpp/dns.h>
+    #include <dpp/restrequest.h>
+    #include <dpp/unicode_emoji.h>
+}

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