boostorg · ClausKlein · Feb 12, 2026 · Feb 15, 2026 · Feb 15, 2026 · Feb 15, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -243,8 +243,8 @@ jobs:
     needs: posix
     runs-on: ubuntu-latest
     steps:
-    - name: Coveralls Finished
-      uses: coverallsapp/github-action@master
-      with:
-        github-token: ${{ secrets.github_token }}
-        parallel-finished: true
+      - name: Coveralls Finished
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.github_token }}
+          parallel-finished: true
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,2 @@
+build/
+compile_commands.json
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -1,46 +1,122 @@
+# -----------------------------------------------------------------------------
+# Boost.Any CMake
+# Handles: no modules, modules, modules + import std;
+# -----------------------------------------------------------------------------
 # Copyright 2019 Mike Dev
 # Distributed under the Boost Software License, Version 1.0.
-# See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
+# -----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.8...3.31 )
-project( boost_any VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX )
+cmake_minimum_required(VERSION 3.21...4.3)
+
+project(boost_any VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
+
+if(PROJECT_IS_TOP_LEVEL)
+    find_package(Boost 1.90.0 CONFIG)
+endif()
+
+# -----------------------------------------------------------------------------
+# User option: enable C++ modules
+# -----------------------------------------------------------------------------
+option(BOOST_USE_MODULES "Build Boost using C++ modules" OFF)
+
+# -----------------------------------------------------------------------------
+# Determine target type and sources
+# -----------------------------------------------------------------------------
+if(BOOST_USE_MODULES)
+
+    # Ensure CMAKE_CXX_STANDARD is set for module detection
+    if(NOT DEFINED CMAKE_CXX_STANDARD)
+        set(CMAKE_CXX_STANDARD 20)
+    endif()
 
-if (BOOST_USE_MODULES)
     add_library(boost_any)
-    target_sources(boost_any PUBLIC
-        FILE_SET modules_public
-            TYPE CXX_MODULES
-            FILES modules/boost_any.cppm
+
+    target_sources(
+        boost_any
+        PUBLIC
+            FILE_SET modules_public
+                TYPE CXX_MODULES
+                FILES modules/boost_any.cppm
     )
 
-    target_compile_features(boost_any PUBLIC cxx_std_20)
+    # Require C++20 for modules
+    target_compile_features(boost_any PUBLIC cxx_std_${CMAKE_CXX_STANDARD})
+
+    # Define macro indicating modules usage
     target_compile_definitions(boost_any PUBLIC BOOST_USE_MODULES)
-    set(__boost_cxx_standard ${CMAKE_CXX_STANDARD})
-    if (NOT __boost_cxx_standard)
-        set(__boost_cxx_standard 20)
-    endif()
-    if (CMAKE_CXX_COMPILER_IMPORT_STD AND ${__boost_cxx_standard} IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD)
-        target_compile_definitions(boost_any PRIVATE BOOST_ANY_USE_STD_MODULE)
-        message(STATUS "Using `import std;`")
+
+    # Check if import std; is available for the current standard
+    if(${CMAKE_CXX_STANDARD} IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD)
+        target_compile_definitions(boost_any PUBLIC BOOST_ANY_USE_STD_MODULE)
+        set_property(TARGET boost_any PROPERTY CXX_MODULE_STD ON)
+        message(STATUS "Boost.Any: Using `import std;`")
     else()
-        message(STATUS "`import std;` is not available")
+        message(WARNING "Boost.Any: `import std;` is not available for C++${CMAKE_CXX_STANDARD}")
     endif()
+
     set(__scope PUBLIC)
+
 else()
+
+    # Modules disabled -> INTERFACE library
     add_library(boost_any INTERFACE)
+
+    # If modules are disabled, require C++17 for headers
+    target_compile_features(boost_any INTERFACE cxx_std_17)
+
+    # Verify interface headers only at top level
+    if(PROJECT_IS_TOP_LEVEL)
+        set(CMAKE_VERIFY_INTERFACE_HEADER_SETS ON)
+    endif()
+
     set(__scope INTERFACE)
+
 endif()
 
-target_include_directories(boost_any ${__scope} include)
-target_link_libraries( boost_any
-    ${__scope}
+# -----------------------------------------------------------------------------
+# Include headers
+# -----------------------------------------------------------------------------
+# Note: usable starting with cmake v3.23
+if(NOT CMAKE_VERSION VERSION_LESS 3.23)
+    target_sources(
+        boost_any
+        PUBLIC
+            FILE_SET headers_public
+                TYPE HEADERS
+                BASE_DIRS include
+                FILES
+                    include/boost/any/bad_any_cast.hpp
+                    include/boost/any/basic_any.hpp
+                    include/boost/any/fwd.hpp
+                    include/boost/any/unique_any.hpp
+                    include/boost/any/detail/config.hpp
+                    include/boost/any/detail/placeholder.hpp
+    )
+else()
+    target_include_directories(boost_any ${__scope} include)
+endif()
+
+# -----------------------------------------------------------------------------
+# Link dependencies
+# -----------------------------------------------------------------------------
+if(PROJECT_IS_TOP_LEVEL)
+    target_link_libraries(boost_any ${__scope} Boost::headers)
+else()
+    target_link_libraries(boost_any
+       ${__scope}
         Boost::config
         Boost::throw_exception
         Boost::type_index
-)
+    )
+endif()
 
-add_library( Boost::any ALIAS boost_any )
+# Alias for convenient import
+add_library(Boost::any ALIAS boost_any)
 
+# -----------------------------------------------------------------------------
+# Testing
+# -----------------------------------------------------------------------------
 if(BUILD_TESTING)
+    enable_testing()
     add_subdirectory(test)
 endif()
diff --git a/include/boost/any.hpp b/include/boost/any.hpp
@@ -5,7 +5,13 @@
 
 #include <boost/any/detail/config.hpp>
 
-#if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
+
+#ifndef BOOST_IN_MODULE_PURVIEW
+// XXX import boost.core;
+#endif
+
+#else
 
 /// \file boost/any.hpp
 /// \brief \copybrief boost::any
@@ -377,6 +383,6 @@ BOOST_ANY_END_MODULE_EXPORT
 // accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#endif  // #if defined(BOOST_USE_MODULES) // !defined(BOOST_ANY_INTERFACE_UNIT)
 
 #endif
diff --git a/include/boost/any/bad_any_cast.hpp b/include/boost/any/bad_any_cast.hpp
@@ -11,7 +11,13 @@
 
 #include <boost/any/detail/config.hpp>
 
-#if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
+
+#ifndef BOOST_IN_MODULE_PURVIEW
+// XXX import boost.core;
+#endif
+
+#else
 
 #ifndef BOOST_ANY_INTERFACE_UNIT
 #include <boost/config.hpp>
@@ -51,6 +57,6 @@ BOOST_ANY_END_MODULE_EXPORT
 
 } // namespace boost
 
-#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#endif  // #if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
 
 #endif // #ifndef BOOST_ANYS_BAD_ANY_CAST_HPP_INCLUDED
diff --git a/include/boost/any/basic_any.hpp b/include/boost/any/basic_any.hpp
@@ -12,7 +12,13 @@
 
 #include <boost/any/detail/config.hpp>
 
-#if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
+
+#ifndef BOOST_IN_MODULE_PURVIEW
+// XXX import boost.core;
+#endif
+
+#else
 
 /// \file boost/any/basic_any.hpp
 /// \brief \copybrief boost::anys::basic_any
@@ -567,6 +573,6 @@ BOOST_ANY_END_MODULE_EXPORT
 
 } // namespace boost
 
-#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#endif  // #if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
 
 #endif // #ifndef BOOST_ANYS_BASIC_ANY_HPP_INCLUDED
diff --git a/include/boost/any/detail/placeholder.hpp b/include/boost/any/detail/placeholder.hpp
@@ -9,7 +9,13 @@
 
 #include <boost/any/detail/config.hpp>
 
-#if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
+
+#ifndef BOOST_IN_MODULE_PURVIEW
+// XXX import boost.core;
+#endif
+
+#else
 
 #ifndef BOOST_ANY_INTERFACE_UNIT
 #include <boost/config.hpp>
@@ -36,6 +42,6 @@ class BOOST_SYMBOL_VISIBLE placeholder {
 } // namespace boost
 /// @endcond
 
-#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#endif  // #if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
 
 #endif  // #ifndef BOOST_ANY_ANYS_DETAIL_PLACEHOLDER_HPP
diff --git a/include/boost/any/fwd.hpp b/include/boost/any/fwd.hpp
@@ -10,13 +10,22 @@
 
 #include <boost/any/detail/config.hpp>
 
-#if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
+
+#ifndef BOOST_IN_MODULE_PURVIEW
+// XXX import boost.core;
+#endif
+
+#else
 
 #ifndef BOOST_ANY_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 # pragma once
 #endif
+
+#include <type_traits>
+
 #endif  // #ifndef BOOST_ANY_INTERFACE_UNIT
 
 /// \file boost/any/fwd.hpp
@@ -66,6 +75,6 @@ namespace detail {
 } // namespace boost
 /// @endcond
 
-#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#endif  // #if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
 
 #endif  // #ifndef BOOST_ANY_ANYS_FWD_HPP
diff --git a/include/boost/any/unique_any.hpp b/include/boost/any/unique_any.hpp
@@ -11,7 +11,13 @@
 
 #include <boost/any/detail/config.hpp>
 
-#if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
+
+#ifndef BOOST_IN_MODULE_PURVIEW
+// XXX import boost.core;
+#endif
+
+#else
 
 /// \file boost/any/unique_any.hpp
 /// \brief \copybrief boost::anys::unique_any
@@ -363,6 +369,6 @@ BOOST_ANY_END_MODULE_EXPORT
 
 } // namespace boost
 
-#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_ANY_INTERFACE_UNIT)
+#endif  // #if defined(BOOST_USE_MODULES) && !defined(BOOST_ANY_INTERFACE_UNIT)
 
 #endif // BOOST_ANYS_UNIQUE_ANY_HPP_INCLUDED
diff --git a/modules/boost_any.cppm b/modules/boost_any.cppm
@@ -6,31 +6,40 @@
 // To compile manually use a command like the following:
 // clang++ -I ../include -std=c++20 --precompile -x c++-module any.cppm
 
+// Global module fragment.
 module;
 
 #include <boost/assert.hpp>
 #include <boost/config.hpp>
 #include <boost/throw_exception.hpp>
-#include <boost/type_index.hpp>
 
-#ifdef BOOST_ANY_USE_STD_MODULE
-import std;
-#else
-#include <memory>
+#include <memory> // for std::addressof
+
+#ifndef BOOST_ANY_USE_STD_MODULE
 #include <stdexcept>
 #include <typeinfo>
 #include <type_traits>
 #include <utility>
 #endif
 
-#define BOOST_ANY_INTERFACE_UNIT
-
+// Begins the module purview
 export module boost.any;
 
+import boost.type_index;
+
+#ifdef BOOST_ANY_USE_STD_MODULE
+import std;
+#endif
+
+// We will use these macros when we get to compatibility headers
+#define BOOST_ANY_INTERFACE_UNIT
+#define BOOST_IN_MODULE_PURVIEW
+
 #ifdef __clang__
 #   pragma clang diagnostic ignored "-Winclude-angled-in-module-purview"
 #endif
 
+// Include the entire library
 #include <boost/any.hpp>
 #include <boost/any/basic_any.hpp>
 #include <boost/any/unique_any.hpp>