Add wrapper for CXX_MODULES

asio/.cmakefiles.txt

@@ -37,6 +37,7 @@ cmake/spell-targets.cmake
 cmake/spell.cmake
 cmake/variables.cmake
 cmake/windows-set-path.cmake
+module/asio.cppm
 src/examples/CMakeLists.txt
 src/tests/CMakeLists.txt
 '

asio/CMakeLists.txt

@@ -25,7 +25,6 @@ elseif(ASIO_HAS_SNPRINTF)
 endif()
 
 option(ASIO_SEPARATE_COMPILATION "build asio lib too" ${PROJECT_IS_TOP_LEVEL})
-
 set(CMAKE_DEBUG_POSTFIX D)
 
 # ---- add dependency libraries ----
@@ -37,6 +36,7 @@ find_package(Threads REQUIRED)
 file(GLOB_RECURSE _asio_implementation "include/asio/*/*.hpp" "include/asio/*.ipp")
 list(FILTER _asio_implementation EXCLUDE REGEX [=[.*/experimental/.*]=])
 
+# asio interface library
 add_library(asio_header INTERFACE)
 add_library(asio::asio_header ALIAS asio_header)
 target_sources(asio_header INTERFACE FILE_SET HEADERS BASE_DIRS include FILES ${_asio_implementation})
@@ -51,17 +51,15 @@ target_link_libraries(asio_header INTERFACE Threads::Threads)
 if(ASIO_SEPARATE_COMPILATION)
   set(_libasio_SOURCES src/asio.cpp)
 
-  # TODO(ssl): find_package(OpenSSL)
+  find_package(OpenSSL)
   if(OpenSSL_FOUND)
-    # TODO(ssl): list(APPEND _libasio_SOURCES src/asio_ssl.cpp)
+    list(APPEND _libasio_SOURCES src/asio_ssl.cpp)
   endif()
 
   set(CMAKE_VERIFY_INTERFACE_HEADER_SETS ${PROJECT_IS_TOP_LEVEL})
 
   file(GLOB_RECURSE _asio_headers "include/asio/*.hpp")
   list(FILTER _asio_headers EXCLUDE REGEX [=[.*/experimental/.*\.hpp]=])
-  list(FILTER _asio_headers EXCLUDE REGEX [=[.*/ssl\.hpp]=])
-  list(FILTER _asio_headers EXCLUDE REGEX [=[.*/ssl/\.*]=])
   list(FILTER _asio_headers EXCLUDE REGEX [=[.*/spawn.*\.hpp]=])
 
   # FIXME: some header in include/asio/detail fails CMAKE_VERIFY_INTERFACE_HEADER_SETS!
@@ -89,7 +87,7 @@ if(ASIO_SEPARATE_COMPILATION)
   endif()
 
   if(OpenSSL_FOUND)
-    target_link_libraries(asio PUBLIC OpenSSL::SSL)
+    target_link_libraries(asio PUBLIC OpenSSL::SSL OpenSSL::Crypto)
   endif()
 endif()
 
@@ -99,6 +97,7 @@ if(NOT CMAKE_SKIP_INSTALL_RULES)
   include(cmake/install-rules.cmake)
   configure_file(asio.pc.cmake asio.pc)
   install(FILES ${PROJECT_BINARY_DIR}/asio.pc DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+  install(DIRECTORY module DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/asio)
 endif()
 
 # ---- Developer mode ----

asio/cmake/install-config.cmake

@@ -2,4 +2,29 @@ include(CMakeFindDependencyMacro)
 find_dependency(Threads)
 find_dependency(OpenSSL)
 
+function(add_asio_module NAME)
+  set(ASIO_ROOT @CMAKE_INSTALL_PREFIX@)
+  message(STATUS "ASIO_ROOT is: ${ASIO_ROOT}")
+
+  add_library(${NAME})
+  target_include_directories(${NAME} PRIVATE ${ASIO_ROOT}/include)
+  target_compile_features(${NAME} PUBLIC cxx_std_23)
+
+  set(CPPdefinitions "@CPPdefinitions@")
+  if(CPPdefinitions)
+    target_compile_definitions(${NAME} PUBLIC ${CPPdefinitions})
+  endif()
+
+  # cmake-format: off
+    target_sources(${NAME} PUBLIC
+        FILE_SET modules_public
+        TYPE CXX_MODULES
+        BASE_DIRS ${ASIO_ROOT}
+        FILES
+            ${ASIO_ROOT}/lib/cmake/asio/module/asio.cppm
+    )
+    # cmake-format: on
+  target_link_libraries(${NAME} PUBLIC OpenSSL::SSL OpenSSL::Crypto)
+endfunction()
+
 include("${CMAKE_CURRENT_LIST_DIR}/asioTargets.cmake")

asio/cmake/install-rules.cmake

@@ -33,8 +33,9 @@ set(ASIO_INSTALL_CMAKEDIR "${CMAKE_INSTALL_LIBDIR}/cmake/${_package}"
 )
 mark_as_advanced(ASIO_INSTALL_CMAKEDIR)
 
-install(FILES cmake/install-config.cmake DESTINATION "${ASIO_INSTALL_CMAKEDIR}" RENAME "${_package}Config.cmake"
-        COMPONENT asio_Development
+configure_file(cmake/install-config.cmake install-config.cmake @ONLY)
+install(FILES ${PROJECT_BINARY_DIR}/install-config.cmake DESTINATION "${ASIO_INSTALL_CMAKEDIR}"
+        RENAME "${_package}Config.cmake" COMPONENT asio_Development
 )
 
 install(FILES "${PROJECT_BINARY_DIR}/${_package}ConfigVersion.cmake" DESTINATION "${ASIO_INSTALL_CMAKEDIR}"

asio/module/asio.cppm

@@ -0,0 +1,67 @@
+module;
+
+#include <asio.hpp>
+#include <asio/ssl.hpp>
+
+export module asio;
+
+namespace asio {
+export using asio::io_context;
+export using asio::post;
+export using asio::any_completion_executor;
+export using asio::any_io_executor;
+export using asio::bad_executor;
+export using asio::cancellation_signal;
+export using asio::cancellation_slot;
+export using asio::cancellation_state;
+export using asio::cancellation_type;
+export using asio::coroutine;
+export using asio::detached_t;
+export using asio::execution_context;
+export using asio::executor;
+export using asio::executor_arg_t;
+export using asio::invalid_service_owner;
+export using asio::io_context;
+export using asio::multiple_exceptions;
+export using asio::service_already_exists;
+export using asio::static_thread_pool;
+export using asio::system_context;
+export using asio::system_executor;
+export using asio::thread_pool;
+export using asio::awaitable;
+export using asio::deferred;
+export using asio::detached;
+export using asio::connect;
+export using asio::async_connect;
+export using asio::buffer;
+export using asio::socket_base;
+export using asio::co_spawn;
+
+namespace error {
+export using asio::error::make_error_code;
+}
+
+namespace this_coro {
+export using asio::this_coro::executor;
+}
+
+namespace ip {
+export using asio::ip::tcp;
+export using asio::ip::address;
+export using asio::ip::address_v4;
+}
+
+namespace ssl {
+export using asio::ssl::context;
+export using asio::ssl::context_base;
+export using asio::ssl::host_name_verification;
+export using asio::ssl::stream_base;
+export using asio::ssl::verify_context;
+export using asio::ssl::stream;
+namespace error {
+export using asio::ssl::error::stream_errors;
+export using asio::ssl::error::make_error_code;
+}
+}
+
+}

asio/src/examples/CMakeLists.txt

@@ -3,8 +3,34 @@ cmake_minimum_required(VERSION 3.25...3.31)
 project(asio_examples LANGUAGES CXX)
 
 if(PROJECT_IS_TOP_LEVEL)
-  find_package(asio 1.32.0.1 EXACT REQUIRED)
+  # Find the Asio package containing the function to build the module
+  find_package(asio 1.32.0.1 EXACT REQUIRED HINT ../stagedir/lib)
   enable_testing()
+
+  # Use modules?
+  unset(USE_MODULES)
+  set(CMAKE_CXX_STANDARD 23)
+  set(CMAKE_CXX_EXTENSIONS OFF)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.28.4 AND CMAKE_GENERATOR STREQUAL "Ninja")
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 20.0)
+      set(USE_MODULES TRUE)
+      # see https://releases.llvm.org/15.0.0/projects/libcxx/docs/ReleaseNotes.html
+      # Always use libc++
+      add_compile_options(-fexperimental-library)
+      add_link_options(-lc++experimental)
+      add_compile_options(-stdlib=libc++)
+      add_link_options(-stdlib=libc++)
+    elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 15.0)
+      set(USE_MODULES TRUE)
+    endif()
+    message(STATUS "CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES=${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES}")
+  endif()
+  if(USE_MODULES)
+    # Build the asio module
+    add_asio_module(asio_module)
+  endif()
+
 endif()
 
 set(ALL_EXAMPLES callback_wrapper)
@@ -14,6 +40,11 @@ message(STATUS "Examples to be built: ${ALL_EXAMPLES}")
 foreach(example ${ALL_EXAMPLES})
   add_executable(${example})
   target_sources(${example} PRIVATE cpp20/operations/${example}.cpp)
-  target_link_libraries(${example} asio::asio_header)
+  if(USE_MODULES)
+    target_link_libraries(${example} asio_module)
+    target_compile_definitions(${example} PUBLIC USE_MODULES)
+  else()
+    target_link_libraries(${example} asio::asio_header)
+  endif()
   add_test(NAME ${example} COMMAND echo Test | ${example})
 endforeach()

asio/src/examples/cpp20/operations/callback_wrapper.cpp

@@ -8,8 +8,25 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <asio.hpp>
-#include <iostream>
+#ifdef USE_MODULES
+#  ifdef HAS_STDLIB_MODULES
+import std;
+import std.compat;
+#  else
+#    include <cstdlib>
+#    include <exception>
+#    include <future>
+#    include <iostream>
+#    include <string>
+#    include <system_error>
+#    include <thread>
+#    include <utility>
+#  endif
+import asio;
+#  else
+#    include <asio.hpp>
+#    include <iostream>
+#  endif
 
 //------------------------------------------------------------------------------