From 25eb738ac4348f5f0f582b99f199ef5d06e1fea2 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Fri, 23 Jan 2026 11:06:41 +0100
Subject: [PATCH 1/3] Initial impl

---
 CMakeLists.txt                               |  6 +++
 include/boost/corosio/acceptor.hpp           |  5 +++
 include/boost/corosio/endpoint.hpp           |  5 +++
 include/boost/corosio/io_buffer_param.hpp    |  5 +++
 include/boost/corosio/io_context.hpp         |  5 +++
 include/boost/corosio/io_object.hpp          |  5 +++
 include/boost/corosio/io_stream.hpp          |  5 +++
 include/boost/corosio/read.hpp               |  5 +++
 include/boost/corosio/resolver.hpp           |  5 +++
 include/boost/corosio/resolver_results.hpp   |  5 +++
 include/boost/corosio/signal_set.hpp         |  5 +++
 include/boost/corosio/socket.hpp             |  5 +++
 include/boost/corosio/tcp_server.hpp         |  5 +++
 include/boost/corosio/timer.hpp              |  5 +++
 include/boost/corosio/tls/context.hpp        |  5 +++
 include/boost/corosio/tls/openssl_stream.hpp |  5 +++
 include/boost/corosio/tls/tls_stream.hpp     |  5 +++
 include/boost/corosio/tls/wolfssl_stream.hpp |  5 +++
 include/boost/corosio/write.hpp              |  5 +++
 modules/boost_corosio.cppm                   | 41 ++++++++++++++++++++
 20 files changed, 137 insertions(+)
 create mode 100644 modules/boost_corosio.cppm

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8026f95e..b90dc5bb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,6 +38,7 @@ option(BOOST_COROSIO_BUILD_BENCH "Build boost::corosio benchmarks" ${BOOST_COROS
 option(BOOST_COROSIO_BUILD_EXAMPLES "Build boost::corosio examples" ${BOOST_COROSIO_IS_ROOT})
 option(BOOST_COROSIO_BUILD_DOCS "Build boost::corosio documentation" OFF)
 option(BOOST_COROSIO_MRDOCS_BUILD "Building for MrDocs documentation generation" OFF)
+option(BOOST_COROSIO_USE_MODULES "Whether to build boost::corosio using C++20 modules or not" OFF)
 
 # Check if environment variable BOOST_SRC_DIR is set
 if (NOT DEFINED BOOST_SRC_DIR AND DEFINED ENV{BOOST_SRC_DIR})
@@ -185,6 +186,11 @@ add_library(boost_corosio ${BOOST_COROSIO_HEADERS} ${BOOST_COROSIO_SOURCES})
 add_library(Boost::corosio ALIAS boost_corosio)
 boost_corosio_setup_properties(boost_corosio)
 
+if (BOOST_COROSIO_USE_MODULES)
+    target_sources(boost_corosio PUBLIC FILE_SET CXX_MODULES BASE_DIRS modules FILES modules/boost_corosio.cppm)
+    target_compile_definitions(boost_corosio PUBLIC BOOST_COROSIO_USE_MODULES)
+endif()
+
 #-------------------------------------------------
 #
 # WolfSSL
diff --git a/include/boost/corosio/acceptor.hpp b/include/boost/corosio/acceptor.hpp
index 7863a387..7804988a 100644
--- a/include/boost/corosio/acceptor.hpp
+++ b/include/boost/corosio/acceptor.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_ACCEPTOR_HPP
 #define BOOST_COROSIO_ACCEPTOR_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/detail/except.hpp>
 #include <boost/corosio/io_object.hpp>
@@ -286,3 +290,4 @@ class BOOST_COROSIO_DECL acceptor : public io_object
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/endpoint.hpp b/include/boost/corosio/endpoint.hpp
index 7ca1cb9f..219d02d8 100644
--- a/include/boost/corosio/endpoint.hpp
+++ b/include/boost/corosio/endpoint.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_ENDPOINT_HPP
 #define BOOST_COROSIO_ENDPOINT_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/url/ipv4_address.hpp>
 #include <boost/url/ipv6_address.hpp>
@@ -187,3 +191,4 @@ class endpoint
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/io_buffer_param.hpp b/include/boost/corosio/io_buffer_param.hpp
index 4a14e1e5..da116678 100644
--- a/include/boost/corosio/io_buffer_param.hpp
+++ b/include/boost/corosio/io_buffer_param.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_IO_BUFFER_PARAM_HPP
 #define BOOST_COROSIO_IO_BUFFER_PARAM_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/capy/buffers.hpp>
 
@@ -383,3 +387,4 @@ class io_buffer_param
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/io_context.hpp b/include/boost/corosio/io_context.hpp
index d9378767..baca061f 100644
--- a/include/boost/corosio/io_context.hpp
+++ b/include/boost/corosio/io_context.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_IO_CONTEXT_HPP
 #define BOOST_COROSIO_IO_CONTEXT_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/detail/scheduler.hpp>
 #include <boost/corosio/detail/unique_ptr.hpp>
@@ -433,3 +437,4 @@ get_executor() const noexcept ->
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/io_object.hpp b/include/boost/corosio/io_object.hpp
index df380cea..78eef6bb 100644
--- a/include/boost/corosio/io_object.hpp
+++ b/include/boost/corosio/io_object.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_IO_OBJECT_HPP
 #define BOOST_COROSIO_IO_OBJECT_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/capy/ex/execution_context.hpp>
 
@@ -70,3 +74,4 @@ class BOOST_COROSIO_DECL io_object
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/io_stream.hpp b/include/boost/corosio/io_stream.hpp
index 03b8ed75..f5d3e083 100644
--- a/include/boost/corosio/io_stream.hpp
+++ b/include/boost/corosio/io_stream.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_IO_STREAM_HPP
 #define BOOST_COROSIO_IO_STREAM_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/io_object.hpp>
 #include <boost/capy/io_result.hpp>
@@ -247,3 +251,4 @@ class BOOST_COROSIO_DECL io_stream : public io_object
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/read.hpp b/include/boost/corosio/read.hpp
index d9f9e7f6..145e497c 100644
--- a/include/boost/corosio/read.hpp
+++ b/include/boost/corosio/read.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_READ_HPP
 #define BOOST_COROSIO_READ_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/io_stream.hpp>
 #include <boost/capy/io_result.hpp>
@@ -218,3 +222,4 @@ read(io_stream& ios, std::string& s)
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/resolver.hpp b/include/boost/corosio/resolver.hpp
index 3d40e1b4..669d1107 100644
--- a/include/boost/corosio/resolver.hpp
+++ b/include/boost/corosio/resolver.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_RESOLVER_HPP
 #define BOOST_COROSIO_RESOLVER_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/detail/except.hpp>
 #include <boost/corosio/io_object.hpp>
@@ -341,3 +345,4 @@ class BOOST_COROSIO_DECL resolver : public io_object
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/resolver_results.hpp b/include/boost/corosio/resolver_results.hpp
index ac7a9d6d..22f02474 100644
--- a/include/boost/corosio/resolver_results.hpp
+++ b/include/boost/corosio/resolver_results.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_RESOLVER_RESULTS_HPP
 #define BOOST_COROSIO_RESOLVER_RESULTS_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/endpoint.hpp>
 
@@ -206,3 +210,4 @@ class resolver_results
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/signal_set.hpp b/include/boost/corosio/signal_set.hpp
index 9a335f3d..e5783729 100644
--- a/include/boost/corosio/signal_set.hpp
+++ b/include/boost/corosio/signal_set.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_SIGNAL_SET_HPP
 #define BOOST_COROSIO_SIGNAL_SET_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/detail/except.hpp>
 #include <boost/corosio/io_object.hpp>
@@ -355,3 +359,4 @@ class BOOST_COROSIO_DECL signal_set : public io_object
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/socket.hpp b/include/boost/corosio/socket.hpp
index ad767d37..35a53b9c 100644
--- a/include/boost/corosio/socket.hpp
+++ b/include/boost/corosio/socket.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_SOCKET_HPP
 #define BOOST_COROSIO_SOCKET_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/detail/except.hpp>
 #include <boost/corosio/io_stream.hpp>
@@ -335,3 +339,4 @@ class BOOST_COROSIO_DECL socket : public io_stream
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/tcp_server.hpp b/include/boost/corosio/tcp_server.hpp
index 45c0f4f9..d16406d1 100644
--- a/include/boost/corosio/tcp_server.hpp
+++ b/include/boost/corosio/tcp_server.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_TCP_SERVER_HPP
 #define BOOST_COROSIO_TCP_SERVER_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/acceptor.hpp>
 #include <boost/corosio/socket.hpp>
@@ -335,3 +339,4 @@ class BOOST_COROSIO_DECL
 } // boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/timer.hpp b/include/boost/corosio/timer.hpp
index dfea548e..96f2851c 100644
--- a/include/boost/corosio/timer.hpp
+++ b/include/boost/corosio/timer.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_TIMER_HPP
 #define BOOST_COROSIO_TIMER_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/detail/except.hpp>
 #include <boost/corosio/io_object.hpp>
@@ -218,3 +222,4 @@ class BOOST_COROSIO_DECL timer : public io_object
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/tls/context.hpp b/include/boost/corosio/tls/context.hpp
index 2a1591e1..0beb888a 100644
--- a/include/boost/corosio/tls/context.hpp
+++ b/include/boost/corosio/tls/context.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_TLS_CONTEXT_HPP
 #define BOOST_COROSIO_TLS_CONTEXT_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/system/result.hpp>
 
@@ -865,3 +869,4 @@ class BOOST_COROSIO_DECL context
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/tls/openssl_stream.hpp b/include/boost/corosio/tls/openssl_stream.hpp
index 1d9d6eef..4267ef6c 100644
--- a/include/boost/corosio/tls/openssl_stream.hpp
+++ b/include/boost/corosio/tls/openssl_stream.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_TLS_OPENSSL_STREAM_HPP
 #define BOOST_COROSIO_TLS_OPENSSL_STREAM_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/tls/context.hpp>
 #include <boost/corosio/tls/tls_stream.hpp>
 
@@ -69,3 +73,4 @@ class BOOST_COROSIO_DECL openssl_stream : public tls_stream
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/tls/tls_stream.hpp b/include/boost/corosio/tls/tls_stream.hpp
index 694cc271..81687dfb 100644
--- a/include/boost/corosio/tls/tls_stream.hpp
+++ b/include/boost/corosio/tls/tls_stream.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_TLS_TLS_STREAM_HPP
 #define BOOST_COROSIO_TLS_TLS_STREAM_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/capy/io_result.hpp>
 #include <boost/corosio/io_stream.hpp>
@@ -263,3 +267,4 @@ class BOOST_COROSIO_DECL tls_stream : public io_stream
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/tls/wolfssl_stream.hpp b/include/boost/corosio/tls/wolfssl_stream.hpp
index 80850f82..e94a6aba 100644
--- a/include/boost/corosio/tls/wolfssl_stream.hpp
+++ b/include/boost/corosio/tls/wolfssl_stream.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_TLS_WOLFSSL_STREAM_HPP
 #define BOOST_COROSIO_TLS_WOLFSSL_STREAM_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/tls/context.hpp>
 #include <boost/corosio/tls/tls_stream.hpp>
@@ -71,3 +75,4 @@ class BOOST_COROSIO_DECL
 } // namespace boost
 
 #endif
+#endif
diff --git a/include/boost/corosio/write.hpp b/include/boost/corosio/write.hpp
index b223efeb..7b9f4dd6 100644
--- a/include/boost/corosio/write.hpp
+++ b/include/boost/corosio/write.hpp
@@ -10,6 +10,10 @@
 #ifndef BOOST_COROSIO_WRITE_HPP
 #define BOOST_COROSIO_WRITE_HPP
 
+#if !defined(BOOST_COROSIO_SOURCE) && defined(BOOST_COROSIO_USE_MODULES)
+import boost.corosio;
+#else
+
 #include <boost/corosio/detail/config.hpp>
 #include <boost/corosio/io_stream.hpp>
 #include <boost/capy/io_result.hpp>
@@ -99,3 +103,4 @@ write(io_stream& ios, ConstBufferSequence const& buffers)
 } // namespace boost
 
 #endif
+#endif
diff --git a/modules/boost_corosio.cppm b/modules/boost_corosio.cppm
new file mode 100644
index 00000000..16fe9b00
--- /dev/null
+++ b/modules/boost_corosio.cppm
@@ -0,0 +1,41 @@
+module;
+
+#include <boost/corosio.hpp>
+
+export module boost.corosio;
+
+export namespace boost::corosio {
+
+using corosio::acceptor;
+using corosio::endpoint;
+using corosio::io_buffer_param;
+using corosio::io_context;
+using corosio::io_object;
+using corosio::io_stream;
+using corosio::read;
+using corosio::resolve_flags;
+using corosio::resolver;
+using corosio::resolver_entry;
+using corosio::resolver_results;
+using corosio::signal_set;
+using corosio::socket;
+using corosio::tcp_server;
+using corosio::timer;
+using corosio::write;
+
+// I think this should be in tls
+using corosio::tls_stream;
+using corosio::openssl_stream;
+using corosio::wolfssl_stream;
+
+namespace tls {
+using corosio::tls::context;
+using corosio::tls::file_format;
+using corosio::tls::password_purpose;
+using corosio::tls::revocation_policy;
+using corosio::tls::role;
+using corosio::tls::verify_mode;
+using corosio::tls::version;
+} // namespace tls
+
+} // namespace boost::corosio

From 1b0964029e2c20dd7addbe2042c7333689b60649 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Fri, 23 Jan 2026 11:13:27 +0100
Subject: [PATCH 2/3] Fix build errors without modules

---
 example/client/http_client.cpp | 6 +++---
 test/unit/resolver.cpp         | 1 +
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/example/client/http_client.cpp b/example/client/http_client.cpp
index 59a587ea..d9e397bc 100644
--- a/example/client/http_client.cpp
+++ b/example/client/http_client.cpp
@@ -35,8 +35,8 @@ do_request(
         "Host: " + std::string(host) + "\r\n"
         "Connection: close\r\n"
         "\r\n";
-    (co_await corosio::write(
-        stream, capy::const_buffer(request.data(), request.size()))).value();
+    co_await corosio::write(
+        stream, capy::const_buffer(request.data(), request.size()));
 
     // Read the entire response
     std::string response;
@@ -59,7 +59,7 @@ run_client(
     s.open();
 
     // Connect to the server (throws on error)
-    (co_await s.connect(corosio::endpoint(addr, port))).value();
+    co_await s.connect(corosio::endpoint(addr, port));
 
     co_await do_request(s, addr.to_string());
 }
diff --git a/test/unit/resolver.cpp b/test/unit/resolver.cpp
index 5f939327..9bee0e70 100644
--- a/test/unit/resolver.cpp
+++ b/test/unit/resolver.cpp
@@ -21,6 +21,7 @@
 #include <boost/capy/cond.hpp>
 #include <boost/capy/ex/run_async.hpp>
 #include <boost/capy/task.hpp>
+#include <boost/url/ipv4_address.hpp>
 
 #include "test_suite.hpp"
 

From 712f4a2588734387e7a6482c271dded1d2c7e222 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Fri, 23 Jan 2026 16:02:50 +0100
Subject: [PATCH 3/3] changes

---
 modules/boost_corosio.cppm | 7 +++++++
 test/unit/io_context.cpp   | 1 +
 test/unit/resolver.cpp     | 1 +
 3 files changed, 9 insertions(+)

diff --git a/modules/boost_corosio.cppm b/modules/boost_corosio.cppm
index 16fe9b00..3bc95037 100644
--- a/modules/boost_corosio.cppm
+++ b/modules/boost_corosio.cppm
@@ -22,6 +22,10 @@ using corosio::socket;
 using corosio::tcp_server;
 using corosio::timer;
 using corosio::write;
+using corosio::operator|;
+using corosio::operator&;
+using corosio::operator&=;
+using corosio::operator|=;
 
 // I think this should be in tls
 using corosio::tls_stream;
@@ -38,4 +42,7 @@ using corosio::tls::verify_mode;
 using corosio::tls::version;
 } // namespace tls
 
+
 } // namespace boost::corosio
+
+
diff --git a/test/unit/io_context.cpp b/test/unit/io_context.cpp
index 79ea1907..c99c9394 100644
--- a/test/unit/io_context.cpp
+++ b/test/unit/io_context.cpp
@@ -11,6 +11,7 @@
 #include <boost/corosio/io_context.hpp>
 
 #include <boost/capy/concept/executor.hpp>
+#include <boost/capy/coro.hpp>
 
 #include <atomic>
 #include <chrono>
diff --git a/test/unit/resolver.cpp b/test/unit/resolver.cpp
index 9bee0e70..f7d4cc71 100644
--- a/test/unit/resolver.cpp
+++ b/test/unit/resolver.cpp
@@ -22,6 +22,7 @@
 #include <boost/capy/ex/run_async.hpp>
 #include <boost/capy/task.hpp>
 #include <boost/url/ipv4_address.hpp>
+#include <boost/url/ipv6_address.hpp>
 
 #include "test_suite.hpp"