C++20 modules support in CMake

.github/workflows/ubuntu.yml

@@ -10,24 +10,27 @@ jobs:
       fail-fast: false
       matrix:
         compiler:
-        - { cc: "gcc-11",   cxx: "g++-11",     os: "ubuntu-22.04", nonascii: "TRUE" }
-        - { cc: "gcc-11",   cxx: "g++-11",     os: "ubuntu-22.04", nonascii: "FALSE" }
-        - { cc: "gcc-12",   cxx: "g++-12",     os: "ubuntu-22.04", nonascii: "FALSE" }
-        - { cc: "gcc-13",   cxx: "g++-13",     os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "gcc-14",   cxx: "g++-14",     os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "gcc-15",   cxx: "g++-15",     os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-13", cxx: "clang++-13", os: "ubuntu-22.04", nonascii: "FALSE" }
-        - { cc: "clang-14", cxx: "clang++-14", os: "ubuntu-22.04", nonascii: "FALSE" }
-        - { cc: "clang-15", cxx: "clang++-15", os: "ubuntu-22.04", nonascii: "FALSE" }
-        - { cc: "clang-16", cxx: "clang++-16", os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-17", cxx: "clang++-17", os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-18", cxx: "clang++-18", os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-19", cxx: "clang++-19", os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-20", cxx: "clang++-20", os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-21", cxx: "clang++-21", os: "ubuntu-24.04", nonascii: "FALSE" }
-        - { cc: "clang-22", cxx: "clang++-22", os: "ubuntu-24.04", nonascii: "FALSE" }
+        - { cc: "gcc-11",   cxx: "g++-11",     os: "ubuntu-22.04", nonascii: "TRUE",  modules: "FALSE", import_std: "FALSE" }
+        - { cc: "gcc-11",   cxx: "g++-11",     os: "ubuntu-22.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "gcc-12",   cxx: "g++-12",     os: "ubuntu-22.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "gcc-13",   cxx: "g++-13",     os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "gcc-14",   cxx: "g++-14",     os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "gcc-15",   cxx: "g++-15",     os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-13", cxx: "clang++-13", os: "ubuntu-22.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-14", cxx: "clang++-14", os: "ubuntu-22.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-15", cxx: "clang++-15", os: "ubuntu-22.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-16", cxx: "clang++-16", os: "ubuntu-22.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-17", cxx: "clang++-17", os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-18", cxx: "clang++-18", os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-19", cxx: "clang++-19", os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-19", cxx: "clang++-19", os: "ubuntu-24.04", nonascii: "FALSE", modules: "TRUE",  import_std: "FALSE" }
+        - { cc: "clang-19", cxx: "clang++-19", os: "ubuntu-24.04", nonascii: "FALSE", modules: "TRUE",  import_std: "TRUE"  }
+        - { cc: "clang-20", cxx: "clang++-20", os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-21", cxx: "clang++-21", os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-22", cxx: "clang++-22", os: "ubuntu-24.04", nonascii: "FALSE", modules: "FALSE", import_std: "FALSE" }
+        - { cc: "clang-22", cxx: "clang++-22", os: "ubuntu-24.04", nonascii: "FALSE", modules: "TRUE",  import_std: "FALSE" }
 
-    name: "${{ format('{0} NONASCII={1}', matrix.compiler.cc, matrix.compiler.nonascii) }}"
+    name: "${{ format('{0} NONASCII={1} MODULES={2} IMPORT_STD={3}', matrix.compiler.cc, matrix.compiler.nonascii, matrix.compiler.modules, matrix.compiler.import_std) }}"
     runs-on: ${{ matrix.compiler.os }}
     steps:
     - uses: actions/checkout@v6
@@ -36,24 +39,23 @@ jobs:
       run: |
         if [[ "${{ matrix.compiler.cc }}" == "clang"* ]]; then
           wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
-          # Add repositories based on Ubuntu version
-          if [[ "${{ matrix.compiler.os }}" == "ubuntu-22.04" ]]; then
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-13 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-14 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-15 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-16 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-17 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-18 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy main"
-          elif [[ "${{ matrix.compiler.os }}" == "ubuntu-24.04" ]]; then
-            sudo apt-add-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble-19 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble-20 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble-21 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble-22 main"
-            sudo apt-add-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble main"
-          fi
+
+          clang_version="${{ matrix.compiler.cc }}"
+          clang_version="${clang_version#clang-}"
+          ubuntu_codename="$(lsb_release -cs)"
+
+          sudo apt-add-repository "deb http://apt.llvm.org/${ubuntu_codename}/ llvm-toolchain-${ubuntu_codename}-${clang_version} main"
           sudo apt update
           sudo apt install ${{ matrix.compiler.cc }} -y
+
+          if [[ "${{ matrix.compiler.import_std }}" == "TRUE" ]]; then
+            # Note: std module is currently supported only with libc++
+            sudo apt install -y \
+              "libclang-rt-${clang_version}-dev" \
+              "libc++-${clang_version}-dev" \
+              "libc++abi-${clang_version}-dev" \
+              "clang-tools-${clang_version}"
+          fi
         fi
 
     - name: Configure gcc
@@ -67,20 +69,42 @@ jobs:
     - name: Build Release
       run: |
         rm -rf build
-        mkdir build
-        cd build
-        cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=${{ matrix.compiler.cxx }} -DMAGIC_ENUM_OPT_ENABLE_NONASCII:BOOL=${{ matrix.compiler.nonascii }}
-        cmake --build . -j 4 --config Release
-        ctest --output-on-failure -C Release
+        cmake -S . -B build \
+          -DCMAKE_BUILD_TYPE=Release \
+          -DCMAKE_CXX_COMPILER=${{ matrix.compiler.cxx }} \
+          -DMAGIC_ENUM_OPT_ENABLE_NONASCII:BOOL=${{ matrix.compiler.nonascii }} \
+          -DMAGIC_ENUM_USE_MODULES:BOOL=${{ matrix.compiler.modules }} \
+          ${{ matrix.compiler.modules == 'TRUE' && '-G Ninja' || '' }}
+        cmake --build build -j 4 --config Release
+        ctest --test-dir build --output-on-failure -C Release
 
     - name: Build Debug
       run: |
         rm -rf build
-        mkdir build
-        cd build
-        cmake .. -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_COMPILER=${{ matrix.compiler.cxx }} -DMAGIC_ENUM_OPT_ENABLE_NONASCII:BOOL=${{ matrix.compiler.nonascii }}
-        cmake --build . -j 4 --config Debug
-        ctest --output-on-failure -C Debug
+        cmake -S . -B build \
+          -DCMAKE_BUILD_TYPE=Debug \
+          -DCMAKE_CXX_COMPILER=${{ matrix.compiler.cxx }} \
+          -DMAGIC_ENUM_OPT_ENABLE_NONASCII:BOOL=${{ matrix.compiler.nonascii }} \
+          -DMAGIC_ENUM_USE_MODULES:BOOL=${{ matrix.compiler.modules }} \
+          ${{ matrix.compiler.modules == 'TRUE' && '-G Ninja' || '' }}
+        cmake --build build -j 4 --config Debug
+        ctest --test-dir build --output-on-failure -C Debug
+
+    - name: Build with `import std;`
+      if: ${{matrix.compiler.import_std == 'TRUE'}}
+      run: |
+        rm -rf build
+        cmake -S . -B build \
+          -DCMAKE_BUILD_TYPE=Debug \
+          -DCMAKE_CXX_COMPILER=${{ matrix.compiler.cxx }} \
+          -DMAGIC_ENUM_USE_MODULES:BOOL=TRUE \
+          -GNinja \
+          -DCMAKE_CXX_MODULE_STD:BOOL=TRUE \
+          -DCMAKE_EXPERIMENTAL_CXX_IMPORT_STD:STRING=0e5b6991-d74f-4b3d-a41c-cf096e0b2508 \
+          -DCMAKE_CXX_FLAGS:STRING="-stdlib=libc++" \
+          -DCMAKE_CXX_STANDARD=23
+        cmake --build build -j 4 --config Debug
+        ctest --test-dir build --output-on-failure -C Debug
 
     - name: Bazel Test
       working-directory: test

.github/workflows/ubuntu_test_installed_version.yml

@@ -45,6 +45,42 @@ jobs:
           cd build2
           ctest --build-config Debug -j$(nproc)
 
+      - name: clear 
+        run: rm -rf build2
+
+      - name: configure clang
+        run: |
+          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+          sudo apt-add-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble-19 main"
+          sudo apt update
+          sudo apt install clang-19 -y
+      
+      - name: install module library
+        run: |
+          cmake -S. -Bbuild \
+            -GNinja \
+            --log-level=DEBUG \
+            -DCMAKE_INSTALL_PREFIX=./install_dir_module \
+            -DMAGIC_ENUM_USE_MODULES=ON \
+            -DCMAKE_CXX_COMPILER=clang++-19
+          cmake --build build --target magic_enum
+          cmake --install build
+          rm -rf build
+
+      - name: configure with installed module version via cmake
+        run: |
+          CMAKE_PREFIX_PATH="./install_dir_module" cmake -S. -Bbuild2 \
+            -GNinja \
+            -DMAGIC_ENUM_OPT_TEST_INSTALLED_VERSION=1 \
+            -DCMAKE_CXX_COMPILER=clang++-19 \
+            --log-level=DEBUG
+
+      - name: build with installed module version via cmake
+        run: cmake --build build2 -j$(nproc) --target test_flags-cpp20 --verbose
+
+      - name: test
+        run: ctest --test-dir build2 -VV -R test_flags-cpp20
+
       - name: clear 
         run: rm -rf build2
 

CMakeLists.txt

@@ -1,4 +1,11 @@
-cmake_minimum_required(VERSION 3.14)
+cmake_minimum_required(VERSION 3.14...4.20)
+
+if(MAGIC_ENUM_USE_MODULES)
+  set(CMAKE_CXX_EXTENSIONS OFF)
+  if(NOT CMAKE_CXX_STANDARD)
+    set(CMAKE_CXX_STANDARD 20)
+  endif()
+endif()
 
 project(
   magic_enum
@@ -35,20 +42,65 @@ a local magic_enum via pkgconfig" NO
 )
 
 if(${MAGIC_ENUM_OPT_TEST_INSTALLED_VERSION} OR ${MAGIC_ENUM_OPT_TEST_INSTALLED_VERSION_PKGCONFIG})
+  enable_testing()
   add_subdirectory(test)
   return()
 endif()
 
 set(INCLUDES "${CMAKE_CURRENT_SOURCE_DIR}/include/magic_enum")
+set(MODULE "${CMAKE_CURRENT_SOURCE_DIR}/module")
 set(EXPORT_NAMESPACE "${PROJECT_NAME}::")
 
-add_library(${PROJECT_NAME} INTERFACE)
-add_library(${EXPORT_NAMESPACE}${PROJECT_NAME} ALIAS ${PROJECT_NAME})
+function(magic_enum_make_library name)
+
+if(MAGIC_ENUM_USE_MODULES)
+  add_library(${name})
+  target_sources(${name}
+    PUBLIC
+      FILE_SET CXX_MODULES
+      BASE_DIRS "${MODULE}"
+      FILES "${MODULE}/magic_enum.cppm"
+    PUBLIC
+      FILE_SET HEADERS
+      BASE_DIRS "${INCLUDES}"
+      FILES
+        "${INCLUDES}/magic_enum.hpp"
+        "${INCLUDES}/magic_enum_all.hpp"
+        "${INCLUDES}/magic_enum_containers.hpp"
+        "${INCLUDES}/magic_enum_flags.hpp"
+        "${INCLUDES}/magic_enum_format.hpp"
+        "${INCLUDES}/magic_enum_fuse.hpp"
+        "${INCLUDES}/magic_enum_iostream.hpp"
+        "${INCLUDES}/magic_enum_switch.hpp"
+        "${INCLUDES}/magic_enum_utility.hpp"
+  )
+  target_compile_features(${name} PUBLIC cxx_std_20)
+  target_compile_definitions(${name}
+    PUBLIC MAGIC_ENUM_USE_MODULES
+    PRIVATE ${ARGN}
+  )
+  if((CMAKE_CXX_STANDARD IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD) AND CMAKE_CXX_MODULE_STD)
+    message("${name}: using import std")
+    target_compile_features(${name} PRIVATE cxx_std_23)
+    target_compile_definitions(${name} PRIVATE MAGIC_ENUM_USE_STD_MODULE)
+  endif()
+
+  set(__scope PUBLIC)
+else()
+  add_library(${name} INTERFACE)
+  set(__scope INTERFACE)
+endif()
+
+add_library(${EXPORT_NAMESPACE}${name} ALIAS ${name})
 target_include_directories(
-  ${PROJECT_NAME} INTERFACE $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
+  ${name} ${__scope} $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
   $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
 )
 
+endfunction()
+
+magic_enum_make_library(${PROJECT_NAME})
+
 if(MAGIC_ENUM_OPT_BUILD_EXAMPLES)
   add_subdirectory(example)
 endif()
@@ -64,11 +116,13 @@ if(MAGIC_ENUM_OPT_INSTALL)
   include(CPackComponent)
   include(CMakePackageConfigHelpers)
 
+  if(NOT MAGIC_ENUM_USE_MODULES)
+
   install(
     TARGETS "${PROJECT_NAME}"
     EXPORT ${PROJECT_NAME}
     INCLUDES
-    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+      DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     # COMPONENT "${SDK_COMPONENT_NAME}" # component is not allowed for
     # includes!
     # Headers are installed separately! Includes only marks the headers for
@@ -86,6 +140,23 @@ if(MAGIC_ENUM_OPT_INSTALL)
     PATTERN "${PROJECT_INCLUDE_HEADER_PATTERN}"
   )
 
+  else()
+
+  install(
+    TARGETS "${PROJECT_NAME}"
+    EXPORT ${PROJECT_NAME}
+    INCLUDES
+      DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+    FILE_SET HEADERS
+      DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}"
+    FILE_SET CXX_MODULES
+      DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/${PROJECT_NAME}"
+    CXX_MODULES_BMI
+      DESTINATION ""
+  )
+
+  endif()
+
   set(CPACK_PACKAGE_NAME "${PROJECT_NAME}")
   set(CPACK_PACKAGE_DESCRIPTION "${PROJECT_DESCRIPTION}")
   set(CPACK_DEBIAN_PACKAGE_ARCHITECTURE "all")

example/CMakeLists.txt

@@ -1,6 +1,8 @@
 include(CheckCXXCompilerFlag)
 
-set(CMAKE_CXX_STANDARD 17)
+if(NOT MAGIC_ENUM_USE_MODULES)
+    set(CMAKE_CXX_STANDARD 17)
+endif()
 if((CMAKE_CXX_COMPILER_ID MATCHES "GNU") OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang"))
     set(OPTIONS -Wall -Wextra -Wshadow -pedantic-errors -Werror)
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
@@ -28,3 +30,6 @@ make_example(example_switch)
 if(MAGIC_ENUM_OPT_ENABLE_NONASCII)
     make_example(example_nonascii_name)
 endif()
+if(MAGIC_ENUM_USE_MODULES)
+    make_example(example_module_usage)
+endif()

example/enum_flag_example.cpp

@@ -20,6 +20,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <cstdint>
 #include <iostream>
 #include <string>
 

example/example_containers_array.cpp

@@ -21,6 +21,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <cstdint>
 #include <iostream>
 
 #include <magic_enum/magic_enum_containers.hpp>

example/example_module_usage.cpp

@@ -0,0 +1,44 @@
+// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2019 - 2024 Daniil Goncharov <neargye@gmail.com>.
+//
+// Permission is hereby  granted, free of charge, to any  person obtaining a copy
+// of this software and associated  documentation files (the "Software"), to deal
+// in the Software  without restriction, including without  limitation the rights
+// to  use, copy,  modify, merge,  publish, distribute,  sublicense, and/or  sell
+// copies  of  the Software,  and  to  permit persons  to  whom  the Software  is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE  IS PROVIDED "AS  IS", WITHOUT WARRANTY  OF ANY KIND,  EXPRESS OR
+// IMPLIED,  INCLUDING BUT  NOT  LIMITED TO  THE  WARRANTIES OF  MERCHANTABILITY,
+// FITNESS FOR  A PARTICULAR PURPOSE AND  NONINFRINGEMENT. IN NO EVENT  SHALL THE
+// AUTHORS  OR COPYRIGHT  HOLDERS  BE  LIABLE FOR  ANY  CLAIM,  DAMAGES OR  OTHER
+// LIABILITY, WHETHER IN AN ACTION OF  CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include <iostream>
+
+import magic_enum;
+
+enum class Color : int { RED = -10, BLUE = 0, GREEN = 10 };
+
+int main() {
+    for (const auto c : magic_enum::enum_values<Color>()) {
+        std::cout << magic_enum::enum_name(c) << '\n';
+    }
+
+    constexpr auto result = magic_enum::enum_integer(Color::RED) + magic_enum::enum_integer(Color::GREEN);
+    if (result == magic_enum::enum_integer(Color::BLUE)) {
+        std::cout << "RED + GREEN == BLUE\n";
+    }
+
+    using magic_enum::iostream_operators::operator<<;
+    constexpr auto c = Color::GREEN;
+    std::cout << "Color: " << Color::RED << " " << c << '\n';
+
+    return 0;
+}

example/example_switch.cpp

@@ -21,7 +21,9 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <cassert>
 #include <iostream>
+#include <optional>
 
 #define MAGIC_ENUM_ENABLE_HASH
 #include <magic_enum/magic_enum_switch.hpp>