fix ci: turn on import std tests, fix libc++ build (#96)

This PR:
- enables tests with `import std` usage in CI
- add all tests to build with cmake_subdir_test (because there was only a subset of tests supported)
- fixes tests build with `libc++`
- disables some tests with wchar_t with 'libc++'

.github/dependabot.yml

@@ -0,0 +1,11 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: "github-actions" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+        interval: "weekly"

.github/workflows/ci.yml

@@ -20,6 +20,7 @@ jobs:
           - toolset: gcc-14  # Do not remove! It is the only toolset that tests CMake tests down below
             cxxstd: "03,11,14,17,20"
             os: ubuntu-24.04
+            compiler: g++-14
           - toolset: gcc-12
             cxxstd: "03,11,14,17,2a"
             os: ubuntu-22.04
@@ -27,7 +28,7 @@ jobs:
             linkflags: "linkflags=--coverage -lasan -lubsan"
             gcov_tool: "gcov-12"
             launcher: "testing.launcher=LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libasan.so.8"
-          - toolset: gcc-9
+          - toolset: gcc-11
             cxxstd: "03,11,14,17,2a"
             os: ubuntu-22.04
           - toolset: clang
@@ -36,12 +37,17 @@ jobs:
             os: ubuntu-22.04
           - toolset: clang
             cxxstd: "11,14,17,20"
-            os: macos-13
+            os: macos-latest
+          - toolset: clang-19
+            cxxstd: "20,23"
+            os: ubuntu-24.04
+            compiler: clang++-19
+            install: clang-19 llvm-19 libclang-rt-19-dev libc++-19-dev libc++abi-19-dev clang-tools-19
 
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
 
       - name: Install packages
         if: matrix.install
@@ -71,16 +77,49 @@ jobs:
           ./bootstrap.sh
           ./b2 -j4 variant=debug tools/inspect
 
+      - name: Run modules tests without 'import std;'
+        if: ${{matrix.toolset == 'clang-19'}}
+        run: |
+          cd ../boost-root/libs/lexical_cast
+          cmake -S test/cmake_subdir_test -B build_module \
+            -GNinja \
+            -DBUILD_TESTING=1 \
+            -DBOOST_USE_MODULES=1 \
+            -DCMAKE_CXX_COMPILER=clang++-19 \
+            -DCMAKE_C_COMPILER=clang-19
+          cmake --build build_module
+          ctest --test-dir build_module -V --no-tests=error
+          rm -rf build_module
+
+      - name: Run modules tests
+        if: ${{matrix.toolset == 'clang-19'}}
+        run: |
+          cd ../boost-root/libs/lexical_cast
+          cmake -S test/cmake_subdir_test -B build_module \
+            -GNinja \
+            -DBUILD_TESTING=1 \
+            -DBOOST_USE_MODULES=1 \
+            -DCMAKE_CXX_COMPILER=clang++-19 \
+            -DCMAKE_C_COMPILER=clang-19 \
+            -DCMAKE_CXX_FLAGS=-stdlib=libc++ \
+            -DCMAKE_CXX_STANDARD=23 \
+            -DCMAKE_EXPERIMENTAL_CXX_IMPORT_STD=0e5b6991-d74f-4b3d-a41c-cf096e0b2508 \
+            -DCMAKE_CXX_MODULE_STD=ON
+          cmake --build build_module
+          ctest --test-dir build_module -V --no-tests=error
+          rm -rf build_module
+
       - name: Run CMake tests
-        if: ${{matrix.toolset == 'gcc-14'}}
+        if: ${{matrix.toolset == 'gcc-14' || matrix.toolset == 'clang-19'}}
         run: |
           cd ../boost-root/
-          mkdir __build
-          cd __build
-          cmake -DBUILD_TESTING=1 -DBOOST_INCLUDE_LIBRARIES=lexical_cast -DCMAKE_CXX_COMPILER=g++-14 -DCMAKE_C_COMPILER=gcc-14 ..
-          cmake --build . --target tests
-          ctest --output-on-failure --no-tests=error
-          cd ..
+          cmake -S . -B __build \
+            -DBUILD_TESTING=1 \
+            -DBOOST_INCLUDE_LIBRARIES=lexical_cast \
+            -DCMAKE_CXX_COMPILER=${{matrix.compiler}} \
+            -DCMAKE_C_COMPILER=${{matrix.toolset}}
+          cmake --build __build --target tests
+          ctest --test-dir __build --output-on-failure --no-tests=error
           rm -rf __build
 
       - name: Run tests
@@ -138,7 +177,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
 
       - name: Setup Boost
         shell: cmd
@@ -157,7 +196,7 @@ jobs:
           git clone -b %BOOST_BRANCH% --depth 10 https://github.com/boostorg/boost.git boost-root
           cd boost-root
           xcopy /s /e /q %GITHUB_WORKSPACE% libs\%LIBRARY%\
-          git submodule update --init tools/boostdep
+          git submodule update --init tools/boostdep libs/test
           python tools/boostdep/depinst/depinst.py --include benchmark --include example --include examples --include tools --git_args "--jobs 3" %LIBRARY%
           cmd /c bootstrap
 
@@ -170,11 +209,38 @@ jobs:
           cd ../boost-root/
           mkdir __build
           cd __build
-          cmake -DBUILD_TESTING=1 -DBOOST_INCLUDE_LIBRARIES=lexical_cast ..
+          cmake -DBUILD_TESTING=1 -DBOOST_INCLUDE_LIBRARIES=lexical_cast -G Ninja ..
           cmake --build . --target tests --config Debug
           ctest --output-on-failure --no-tests=error -C Debug
-          cd ..
-          rm -rf __build
+
+      - name: Run modules tests
+        if: false
+        #if: ${{matrix.toolset == 'msvc-14.3'}}
+        shell: cmd
+        run: |
+          choco install --no-progress ninja
+          call "C:/Program Files/Microsoft Visual Studio/2022/Enterprise/VC/Auxiliary/Build/vcvarsall.bat" x64
+          cd ../boost-root/libs/lexical_cast
+          rm -rf build_module
+          mkdir build_module
+          cd build_module
+          cmake -DBOOST_USE_MODULES=1 -DCMAKE_CXX_STANDARD=23 -DCMAKE_EXPERIMENTAL_CXX_IMPORT_STD=0e5b6991-d74f-4b3d-a41c-cf096e0b2508 -G Ninja ../test/cmake_subdir_test/
+          cmake --build .
+          ctest --no-tests=error -V
+
+      - name: Run modules tests without 'import std;'
+        if: ${{matrix.toolset == 'msvc-14.3'}}
+        shell: cmd
+        run: |
+          choco install --no-progress ninja
+          call "C:/Program Files/Microsoft Visual Studio/2022/Enterprise/VC/Auxiliary/Build/vcvarsall.bat" x64
+          cd ../boost-root/libs/lexical_cast
+          rm -rf build_module
+          mkdir build_module
+          cd build_module
+          cmake -DBOOST_USE_MODULES=1 -DCMAKE_CXX_STANDARD=20 -G Ninja ../test/cmake_subdir_test/
+          cmake --build .
+          ctest --no-tests=error -V
 
       - name: Run tests
         shell: cmd

CMakeLists.txt

@@ -3,23 +3,43 @@
 # Distributed under the Boost Software License, Version 1.0.
 # https://www.boost.org/LICENSE_1_0.txt
 
-cmake_minimum_required(VERSION 3.5...3.16)
+cmake_minimum_required(VERSION 3.5...4.0)
 
 project(boost_lexical_cast VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
 
-add_library(boost_lexical_cast INTERFACE)
-add_library(Boost::lexical_cast ALIAS boost_lexical_cast)
 
-target_include_directories(boost_lexical_cast INTERFACE include)
+if (BOOST_USE_MODULES)
+    add_library(boost_lexical_cast)
+    target_sources(boost_lexical_cast PUBLIC
+        FILE_SET modules_public TYPE CXX_MODULES FILES
+            ${CMAKE_CURRENT_LIST_DIR}/modules/boost_lexical_cast.cppm
+    )
 
+    target_compile_features(boost_lexical_cast PUBLIC cxx_std_20)
+    target_compile_definitions(boost_lexical_cast PUBLIC BOOST_USE_MODULES)
+    if (CMAKE_CXX_COMPILER_IMPORT_STD)
+        target_compile_definitions(boost_lexical_cast PRIVATE BOOST_LEXICAL_CAST_USE_STD_MODULE)
+        message(STATUS "Using `import std;`")
+    else()
+        message(STATUS "`import std;` is not available")
+    endif()
+    set(__scope PUBLIC)
+else()
+    add_library(boost_lexical_cast INTERFACE)
+    set(__scope INTERFACE)
+endif()
+
+target_include_directories(boost_lexical_cast ${__scope} include)
 target_link_libraries(boost_lexical_cast
-  INTERFACE
+  ${__scope}
     Boost::config
     Boost::container
     Boost::core
     Boost::throw_exception
 )
 
+add_library(Boost::lexical_cast ALIAS boost_lexical_cast)
+
 if(BUILD_TESTING)
   add_subdirectory(test)
 endif()

doc/Jamfile.v2

@@ -1,4 +1,4 @@
-# Copyright Antony Polukhin, 2011-2025.
+# Copyright Antony Polukhin, 2011-2026.
 #
 # Use, modification, and distribution are
 # subject to the Boost Software License, Version 1.0. (See accompanying

doc/lexical_cast.qbk

@@ -3,7 +3,7 @@
     [version 1.0]
     [copyright 2000-2005 Kevlin Henney]
     [copyright 2006-2010 Alexander Nasonov]
-    [copyright 2011-2025 Antony Polukhin]
+    [copyright 2011-2026 Antony Polukhin]
     [category String and text processing]
     [category Miscellaneous]
     [license
@@ -233,8 +233,45 @@ limitation of compiler options that you use.
 
 [endsect]
 
+[section C++20 module]
+
+[caution C++20 module support is on early stage, targets, flags and behavior may change in the future]
+
+If using modern CMake define CMake option `-DBOOST_USE_MODULES=1` to build a C++20 module and
+make the `Boost::lexical_cast` CMake target provide it. After that an explicit usage of C++20 module `boost.lexical_cast` is allowed:
+
+[import ../modules/usage_sample.cpp]
+[lexical_cast_module_example]
+
+The `Boost::lexical_cast` CMake target gives an ability to mix includes and imports of the library in different translation units. Moreover,
+if `BOOST_USE_MODULES` macro is defined then all the `boost/lexical_cast...` includes implicitly do `import boost.lexical_cast;` to give all the
+benefits of modules without changing the existing code.
+
+[note For better compile times make sure that `import std;` is available when building the `boost.lexical_cast` module (in CMake logs there should be
+      a 'Using `import std;`' message). ]
+
+If not using CMake, then the module could be build manually from the `modules/boost_lexical_cast.cppm` file.
+
+For manual module build the following commands could be used for clang compiler:
+
+```
+cd lexical_cast/modules
+clang++ -I ../include -std=c++20 --precompile -x c++-module boost_lexical_cast.cppm
+```
+
+After that, the module could be used in the following way:
+
+```
+clang++ -std=c++20 -fmodule-file=boost_lexical_cast.pcm boost_lexical_cast.pcm usage_sample.cpp
+```
+
+[endsect]
+
 [section Changes]
 
+* [*boost 1.91.0 :]
+    * Added C++20 modules support.
+
 * [*boost 1.86.0 :]
 
     * Fixed conversion of `std::basic_string_view` and `boost::basic_string_view`

example/args_to_numbers.cpp

@@ -1,4 +1,4 @@
-// Copyright Antony Polukhin, 2013-2025.
+// Copyright Antony Polukhin, 2013-2026.
 
 // Distributed under the Boost Software License, Version 1.0.
 // (See the accompanying file LICENSE_1_0.txt
@@ -7,9 +7,10 @@
 //[lexical_cast_args_example
 //`The following example treats command line arguments as a sequence of numeric data
 
-#include <boost/lexical_cast.hpp>
 #include <vector>
 
+#include <boost/lexical_cast.hpp>
+
 int main(int /*argc*/, char * argv[])
 {
     using boost::lexical_cast;

example/generic_stringize.cpp

@@ -1,4 +1,4 @@
-// Copyright Antony Polukhin, 2013-2025.
+// Copyright Antony Polukhin, 2013-2026.
 
 // Distributed under the Boost Software License, Version 1.0.
 // (See the accompanying file LICENSE_1_0.txt
@@ -20,6 +20,12 @@
     Step 1: Making a functor that converts any type to a string and remembers result:
 */
 
+#include <string>
+
+#include <boost/fusion/include/for_each.hpp>
+#include <boost/fusion/adapted/std_tuple.hpp>
+#include <boost/fusion/adapted/std_pair.hpp>
+
 #include <boost/lexical_cast.hpp>
 
 struct stringize_functor {
@@ -38,7 +44,6 @@ public:
 };
 
 //` Step 2: Applying `stringize_functor` to each element in sequence:
-#include <boost/fusion/include/for_each.hpp>
 template <class Sequence>
 std::string stringize(const Sequence& seq) {
     std::string result;
@@ -47,9 +52,6 @@ std::string stringize(const Sequence& seq) {
 }
 
 //` Step 3: Using the `stringize` with different types:
-#include <boost/fusion/adapted/std_tuple.hpp>
-#include <boost/fusion/adapted/std_pair.hpp>
-
 int main() {
     std::tuple<char, int, char, int> decim('-', 10, 'e', 5);
     if (stringize(decim) != "-10e5") {

example/small_examples.cpp

@@ -1,15 +1,16 @@
-// Copyright Antony Polukhin, 2013-2025.
+// Copyright Antony Polukhin, 2013-2026.
 
 // Distributed under the Boost Software License, Version 1.0.
 // (See the accompanying file LICENSE_1_0.txt
 // or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)
 
-#include <boost/lexical_cast.hpp>
-
 #include <array>
 #include <string>
+#include <string.h>
 #include <cstdio>
 
+#include <boost/lexical_cast.hpp>
+
 #ifdef BOOST_MSVC
 #  pragma warning(disable: 4996) // `strerror` is not safe
 #endif

example/variant_to_long_double.cpp

@@ -1,4 +1,4 @@
-// Copyright Antony Polukhin, 2013-2025.
+// Copyright Antony Polukhin, 2013-2026.
 
 // Distributed under the Boost Software License, Version 1.0.
 // (See the accompanying file LICENSE_1_0.txt
@@ -10,9 +10,13 @@
     In this example we'll make a `to_long_double` method that converts value of the Boost.Variant to `long double`.
 */
 
-#include <boost/lexical_cast.hpp>
+#ifdef BOOST_USE_MODULES
+#include <compare>
+#endif
 #include <boost/variant.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 struct to_long_double_functor: boost::static_visitor<long double> {
     template <class T>
     long double operator()(const T& v) const {

include/boost/lexical_cast.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,10 +18,16 @@
 #ifndef BOOST_LEXICAL_CAST_INCLUDED
 #define BOOST_LEXICAL_CAST_INCLUDED
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
+#endif
 
 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
 #define BOOST_LCAST_NO_WCHAR_T
@@ -34,6 +40,7 @@
 
 namespace boost
 {
+BOOST_LEXICAL_CAST_BEGIN_MODULE_EXPORT
     template <typename Target, typename Source>
     inline Target lexical_cast(const Source &arg)
     {
@@ -94,9 +101,12 @@ namespace boost
         );
     }
 
+BOOST_LEXICAL_CAST_END_MODULE_EXPORT
 } // namespace boost
 
 #undef BOOST_LCAST_NO_WCHAR_T
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_INCLUDED
 

include/boost/lexical_cast/bad_lexical_cast.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,6 +18,11 @@
 #ifndef BOOST_LEXICAL_CAST_BAD_LEXICAL_CAST_HPP
 #define BOOST_LEXICAL_CAST_BAD_LEXICAL_CAST_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
@@ -26,9 +31,11 @@
 #include <exception>
 #include <typeinfo>
 #include <boost/throw_exception.hpp>
+#endif
 
 namespace boost
 {
+BOOST_LEXICAL_CAST_BEGIN_MODULE_EXPORT
     // exception used to indicate runtime lexical_cast failure
     class BOOST_SYMBOL_VISIBLE bad_lexical_cast :
     // workaround MSVC bug with std::bad_cast when _HAS_EXCEPTIONS == 0
@@ -80,6 +87,7 @@ namespace boost
         const type_info_t *target;
 #endif
     };
+BOOST_LEXICAL_CAST_END_MODULE_EXPORT
 
     namespace conversion { namespace detail {
 #ifdef BOOST_NO_TYPEID
@@ -97,4 +105,6 @@ namespace boost
 
 } // namespace boost
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_BAD_LEXICAL_CAST_HPP

include/boost/lexical_cast/detail/buffer_view.hpp

@@ -1,4 +1,4 @@
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -7,12 +7,18 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_BUFFER_VIEW_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_BUFFER_VIEW_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
 
 #include <iosfwd>
+#endif
 
 namespace boost { namespace conversion { namespace detail {
 
@@ -55,5 +61,7 @@ namespace boost { namespace conversion { namespace detail {
 
 }}}  // namespace boost::conversion::detail
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_BUFFER_VIEW_HPP
 

include/boost/lexical_cast/detail/config.hpp

@@ -0,0 +1,22 @@
+// Copyright Antony Polukhin, 2021-2026.
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_LEXICAL_CAST_DETAIL_CONFIG_HPP
+#define BOOST_LEXICAL_CAST_DETAIL_CONFIG_HPP
+
+#ifdef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+#   define BOOST_LEXICAL_CAST_BEGIN_MODULE_EXPORT export {
+#   define BOOST_LEXICAL_CAST_END_MODULE_EXPORT }
+#else
+#   define BOOST_LEXICAL_CAST_BEGIN_MODULE_EXPORT
+#   define BOOST_LEXICAL_CAST_END_MODULE_EXPORT
+#endif
+
+#if defined(BOOST_USE_MODULES) && !defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+import boost.lexical_cast;
+#endif
+
+#endif  // #ifndef BOOST_LEXICAL_CAST_DETAIL_CONFIG_HPP

include/boost/lexical_cast/detail/converter_lexical.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,6 +18,11 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
@@ -27,15 +32,11 @@
 #define BOOST_LCAST_NO_WCHAR_T
 #endif
 
+#include <array>
 #include <cstddef>
 #include <string>
 #include <type_traits>
 #include <boost/limits.hpp>
-#include <boost/detail/lcast_precision.hpp>
-
-#include <boost/lexical_cast/detail/widest_char.hpp>
-#include <boost/lexical_cast/detail/is_character.hpp>
-#include <boost/lexical_cast/detail/type_traits.hpp>
 
 #include <array>
 
@@ -43,9 +44,14 @@
 #include <string_view>
 #endif
 
-#include <boost/lexical_cast/detail/buffer_view.hpp>
 #include <boost/container/container_fwd.hpp>
 
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
+#include <boost/lexical_cast/detail/lcast_precision.hpp>
+#include <boost/lexical_cast/detail/widest_char.hpp>
+#include <boost/lexical_cast/detail/is_character.hpp>
+#include <boost/lexical_cast/detail/buffer_view.hpp>
 #include <boost/lexical_cast/detail/converter_lexical_streams.hpp>
 
 namespace boost {
@@ -479,5 +485,7 @@ namespace boost {
 
 #undef BOOST_LCAST_NO_WCHAR_T
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP
 

include/boost/lexical_cast/detail/converter_lexical_streams.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,12 +18,16 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_STREAMS_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_STREAMS_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
 
-
 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
 #define BOOST_LCAST_NO_WCHAR_T
 #endif
@@ -33,9 +37,8 @@
 #include <cstring>
 #include <cstdio>
 #include <type_traits>
+
 #include <boost/limits.hpp>
-#include <boost/detail/lcast_precision.hpp>
-#include <boost/lexical_cast/detail/type_traits.hpp>
 #include <boost/config/workaround.hpp>
 #include <boost/core/snprintf.hpp>
 
@@ -58,21 +61,28 @@
 #include <sstream>
 #endif
 
-#include <boost/lexical_cast/detail/buffer_view.hpp>
-#include <boost/lexical_cast/detail/lcast_char_constants.hpp>
-#include <boost/lexical_cast/detail/lcast_unsigned_converters.hpp>
-#include <boost/lexical_cast/detail/lcast_basic_unlockedbuf.hpp>
-#include <boost/lexical_cast/detail/inf_nan.hpp>
-
-#include <istream>
 
 #include <array>
+#ifndef BOOST_NO_CWCHAR
+#   include <cwchar>
+#endif
+#include <istream>
 
 #include <boost/container/container_fwd.hpp>
 #ifndef BOOST_NO_CWCHAR
 #   include <cwchar>
 #endif
 
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
+#include <boost/lexical_cast/detail/buffer_view.hpp>
+#include <boost/lexical_cast/detail/lcast_char_constants.hpp>
+#include <boost/lexical_cast/detail/lcast_unsigned_converters.hpp>
+#include <boost/lexical_cast/detail/lcast_basic_unlockedbuf.hpp>
+#include <boost/lexical_cast/detail/inf_nan.hpp>
+#include <boost/lexical_cast/detail/lcast_precision.hpp>
+#include <boost/lexical_cast/detail/type_traits.hpp>
+
 // Forward declarations
 namespace boost {
     template<class T, std::size_t N>
@@ -747,5 +757,7 @@ namespace boost { namespace detail { namespace lcast {
 
 #undef BOOST_LCAST_NO_WCHAR_T
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP
 

include/boost/lexical_cast/detail/converter_numeric.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,6 +18,11 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_CONVERTER_NUMERIC_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_CONVERTER_NUMERIC_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
@@ -26,6 +31,9 @@
 #include <type_traits>
 #include <boost/core/cmath.hpp>
 #include <boost/limits.hpp>
+
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
 #include <boost/lexical_cast/detail/type_traits.hpp>
 
 namespace boost { namespace detail {
@@ -176,5 +184,7 @@ struct dynamic_num_converter_impl
 
 }} // namespace boost::detail
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_CONVERTER_NUMERIC_HPP
 

include/boost/lexical_cast/detail/inf_nan.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,6 +18,11 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_INF_NAN_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_INF_NAN_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
@@ -32,6 +37,7 @@
 #include <boost/core/cmath.hpp>
 #include <cstddef>
 #include <cstring>
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 
 #include <boost/lexical_cast/detail/lcast_char_constants.hpp>
 
@@ -183,5 +189,7 @@ namespace boost {
 
 #undef BOOST_LCAST_NO_WCHAR_T
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_INF_NAN_HPP
 

include/boost/lexical_cast/detail/is_character.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,13 +18,20 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_IS_CHARACTER_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_IS_CHARACTER_HPP
 
-#include <type_traits>
+#include <boost/lexical_cast/detail/config.hpp>
 
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
 
+#include <type_traits>
+
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
 namespace boost { namespace detail {
 
 // returns true, if T is one of the character types
@@ -47,5 +54,7 @@ using is_character = std::integral_constant<
 
 }}
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_IS_CHARACTER_HPP
 

include/boost/lexical_cast/detail/lcast_basic_unlockedbuf.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -9,6 +9,12 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_BASIC_UNLOCKEDBUF_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_BASIC_UNLOCKEDBUF_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
@@ -25,6 +31,7 @@
 #ifndef BOOST_NO_CWCHAR
 #   include <cwchar>
 #endif
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 
 namespace boost { namespace detail { namespace lcast {
 
@@ -69,5 +76,7 @@ namespace boost { namespace detail { namespace lcast {
 
 }}} // namespace boost::detail::lcast
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_BASIC_UNLOCKEDBUF_HPP
 

include/boost/lexical_cast/detail/lcast_char_constants.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,10 +18,16 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_LCAST_CHAR_CONSTANTS_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_LCAST_CHAR_CONSTANTS_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 
 namespace boost
 {
@@ -41,6 +47,7 @@ namespace boost
     }
 } // namespace boost
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
 
 #endif // BOOST_LEXICAL_CAST_DETAIL_LCAST_CHAR_CONSTANTS_HPP
 

include/boost/lexical_cast/detail/lcast_precision.hpp

@@ -8,11 +8,21 @@
 #ifndef BOOST_DETAIL_LCAST_PRECISION_HPP_INCLUDED
 #define BOOST_DETAIL_LCAST_PRECISION_HPP_INCLUDED
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+#include <boost/config.hpp>
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#   pragma once
+#endif
+
 #include <climits>
 #include <ios>
 #include <limits>
 
-#include <boost/config.hpp>
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 
 namespace boost { namespace detail {
 
@@ -79,5 +89,7 @@ inline void lcast_set_precision(std::ios_base& stream, Source*, Target*)
 
 }}
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif //  BOOST_DETAIL_LCAST_PRECISION_HPP_INCLUDED
 

include/boost/lexical_cast/detail/lcast_unsigned_converters.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,6 +18,11 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_LCAST_UNSIGNED_CONVERTERS_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_LCAST_UNSIGNED_CONVERTERS_HPP
 
+#include <boost/lexical_cast/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
@@ -49,6 +54,9 @@
 
 #include <boost/lexical_cast/detail/lcast_char_constants.hpp>
 #include <boost/core/noncopyable.hpp>
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
+#include <boost/lexical_cast/detail/lcast_char_constants.hpp>
 
 namespace boost
 {
@@ -294,5 +302,7 @@ namespace boost
     }
 } // namespace boost
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_LCAST_UNSIGNED_CONVERTERS_HPP
 

include/boost/lexical_cast/detail/widest_char.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,13 +18,19 @@
 #ifndef BOOST_LEXICAL_CAST_DETAIL_WIDEST_CHAR_HPP
 #define BOOST_LEXICAL_CAST_DETAIL_WIDEST_CHAR_HPP
 
-#include <type_traits>
+#include <boost/lexical_cast/detail/config.hpp>
 
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
 
+#include <type_traits>
+
+#endif  // #ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 
 namespace boost { namespace detail {
 
@@ -37,5 +43,7 @@ using widest_char = std::conditional<
 
 }} // namespace boost::detail
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_DETAIL_WIDEST_CHAR_HPP
 

include/boost/lexical_cast/try_lexical_convert.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -18,13 +18,19 @@
 #ifndef BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
 #define BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
 
-#include <type_traits>
+#include <boost/lexical_cast/detail/config.hpp>
 
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
+#ifndef BOOST_LEXICAL_CAST_INTERFACE_UNIT
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #   pragma once
 #endif
 
+#include <type_traits>
+#endif
+
 #include <boost/lexical_cast/detail/buffer_view.hpp>
 #include <boost/lexical_cast/detail/is_character.hpp>
 #include <boost/lexical_cast/detail/converter_numeric.hpp>
@@ -45,6 +51,8 @@ namespace boost {
 
     namespace conversion { namespace detail {
 
+BOOST_LEXICAL_CAST_BEGIN_MODULE_EXPORT
+
         template <typename Target, typename Source>
         inline bool try_lexical_convert(const Source& arg, Target& result)
         {
@@ -78,15 +86,20 @@ namespace boost {
                 result
             );
         }
+BOOST_LEXICAL_CAST_END_MODULE_EXPORT
 
     }} // namespace conversion::detail
 
     namespace conversion {
+BOOST_LEXICAL_CAST_BEGIN_MODULE_EXPORT
         // ADL barrier
         using ::boost::conversion::detail::try_lexical_convert;
+BOOST_LEXICAL_CAST_END_MODULE_EXPORT
     }
 
 } // namespace boost
 
+#endif  // #if !defined(BOOST_USE_MODULES) || defined(BOOST_LEXICAL_CAST_INTERFACE_UNIT)
+
 #endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
 

modules/boost_lexical_cast.cppm

@@ -0,0 +1,57 @@
+// Copyright (c) 2016-2025 Antony Polukhin
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// To compile manually use a command like the folowing:
+// clang++ -I ../include -std=c++20 --precompile -x c++-module boost_lexical_cast.cppm
+
+module;
+
+#include <boost/assert.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+#include <boost/container/container_fwd.hpp>
+#include <boost/core/cmath.hpp>
+#include <boost/core/noncopyable.hpp>
+#include <boost/core/snprintf.hpp>
+#include <boost/limits.hpp>
+#include <boost/throw_exception.hpp>
+
+#include <boost/detail/basic_pointerbuf.hpp>
+
+#ifndef BOOST_LEXICAL_CAST_USE_STD_MODULE
+#include <array>
+#include <climits>
+#include <cstddef>
+#include <cstdio>
+#include <cstring>
+#ifndef BOOST_NO_CWCHAR
+#   include <cwchar>
+#endif
+#include <exception>
+#include <iosfwd>
+#include <istream>
+#ifndef BOOST_NO_STD_LOCALE
+#   include <locale>
+#endif
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <typeinfo>
+#include <type_traits>
+#endif
+
+#define BOOST_LEXICAL_CAST_INTERFACE_UNIT
+
+export module boost.lexical_cast;
+
+#ifdef BOOST_LEXICAL_CAST_USE_STD_MODULE
+import std;
+#endif
+
+#ifdef __clang__
+#   pragma clang diagnostic ignored "-Winclude-angled-in-module-purview"
+#endif
+
+#include <boost/lexical_cast.hpp>

modules/usage_sample.cpp

@@ -0,0 +1,16 @@
+// Copyright (c) 2024-2025 Antony Polukhin
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// To compile manually use a command like the following:
+// clang++ -std=c++20 -fmodule-file=lexical_cast.pcm lexical_cast.pcm usage_sample.cpp
+
+//[lexical_cast_module_example
+import boost.lexical_cast;
+
+int main() {
+    return boost::lexical_cast<int>("0");
+}
+//]
+

perf/Jamfile.v2

@@ -1,5 +1,5 @@
 #==============================================================================
-#   Copyright (c) Antony Polukhin, 2012-2024.
+#   Copyright Antony Polukhin, 2012-2026.
 #
 #   Distributed under the Boost Software License, Version 1.0. (See accompanying
 #   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

perf/performance_test.cpp

@@ -1,4 +1,4 @@
-//  (C) Copyright Antony Polukhin, 2012-2025.
+//  (C) Copyright Antony Polukhin, 2012-2026.
 //  Use, modification and distribution are subject to the
 //  Boost Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

test/CMakeLists.txt

@@ -1,65 +1,84 @@
-# Copyright  (c) 2016-2025 Antony Polukhin
+# Copyright Antony Polukhin, 2021-2026.
+#
 # Distributed under the Boost Software License, Version 1.0.
 # See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
 
-include(BoostTest OPTIONAL RESULT_VARIABLE HAVE_BOOST_TEST)
-
-if(NOT HAVE_BOOST_TEST)
-  return()
+if(NOT TARGET tests)
+  add_custom_target(tests)
 endif()
 
-set(BOOST_TEST_LINK_LIBRARIES Boost::lexical_cast Boost::core)
+function(boost_lexical_cast_add_test_impl test_name test_file libs)
+    add_executable(${test_name} ${test_file})
+    target_link_libraries(${test_name} PRIVATE ${libs})
+    add_test(NAME ${test_name} COMMAND ${test_name})
+    add_dependencies(tests ${test_name})
+endfunction()
 
-boost_test(TYPE run SOURCES lexical_cast_test.cpp LINK_LIBRARIES Boost::type_traits)
-boost_test(TYPE run SOURCES loopback_test.cpp)
-boost_test(TYPE run SOURCES abstract_test.cpp)
-boost_test(TYPE run SOURCES noncopyable_test.cpp)
-boost_test(TYPE run SOURCES vc8_bug_test.cpp)
-boost_test(TYPE run SOURCES implicit_convert.cpp)
-boost_test(TYPE run SOURCES wchars_test.cpp)
-boost_test(TYPE run SOURCES float_types_test.cpp)
+function(boost_lexical_cast_add_test name libs)
+    set(test_name lexical_cast_${name})
+    set(test_file ${name}.cpp)
+    boost_lexical_cast_add_test_impl(${test_name} ${test_file} "Boost::lexical_cast;${libs}")
+endfunction()
+
+boost_lexical_cast_add_test(lexical_cast_test Boost::type_traits)
+boost_lexical_cast_add_test(loopback_test "")
+boost_lexical_cast_add_test(abstract_test "")
+boost_lexical_cast_add_test(noncopyable_test "")
+boost_lexical_cast_add_test(vc8_bug_test "")
+boost_lexical_cast_add_test(implicit_convert "")
+boost_lexical_cast_add_test(wchars_test "")
+boost_lexical_cast_add_test(float_types_test "")
 
 if(NOT MSVC)
     # Make sure that LexicalCast works the same way as some of the C++ Standard Libraries
-    boost_test(TYPE run SOURCES float_types_test.cpp COMPILE_DEFINITIONS BOOST_LEXICAL_CAST_DETAIL_TEST_ON_OLD NAME float_types_non_opt)
+    boost_lexical_cast_add_test_impl(lexical_cast_float_types_non_opt float_types_test.cpp Boost::lexical_cast)
+    target_compile_definitions(lexical_cast_float_types_non_opt PRIVATE BOOST_LEXICAL_CAST_DETAIL_TEST_ON_OLD)
 endif()
 
-boost_test(TYPE run SOURCES inf_nan_test.cpp)
-boost_test(TYPE run SOURCES containers_test.cpp)
-boost_test(TYPE run SOURCES empty_input_test.cpp LINK_LIBRARIES Boost::range)
-boost_test(TYPE run SOURCES pointers_test.cpp)
+boost_lexical_cast_add_test(inf_nan_test "")
+boost_lexical_cast_add_test(containers_test "")
+boost_lexical_cast_add_test(empty_input_test Boost::range)
+boost_lexical_cast_add_test(pointers_test "")
 
 if(MSVC)
-    boost_test(TYPE compile SOURCES typedefed_wchar_test.cpp COMPILE_OPTIONS "/Zc:wchar_t-")
-    boost_test(TYPE run SOURCES typedefed_wchar_test_runtime.cpp COMPILE_OPTIONS "/Zc:wchar_t-")
+    add_executable(lexical_cast_typedefed_wchar_test_compile typedefed_wchar_test.cpp)
+    target_compile_options(lexical_cast_typedefed_wchar_test_compile PRIVATE "/Zc:wchar_t-")
+
+    boost_lexical_cast_add_test(typedefed_wchar_test_runtime "")
+    target_compile_options(lexical_cast_typedefed_wchar_test_runtime PRIVATE "/Zc:wchar_t-")
 endif()
 
-boost_test(TYPE run SOURCES no_locale_test.cpp
-    COMPILE_DEFINITIONS BOOST_NO_STD_LOCALE BOOST_LEXICAL_CAST_ASSUME_C_LOCALE
-    LINK_LIBRARIES Boost::range
+boost_lexical_cast_add_test(no_locale_test Boost::range)
+target_compile_definitions(lexical_cast_no_locale_test
+    PRIVATE
+      BOOST_NO_STD_LOCALE
+      BOOST_LEXICAL_CAST_ASSUME_C_LOCALE
 )
 
-boost_test(TYPE run SOURCES no_exceptions_test.cpp
-    COMPILE_OPTIONS "-fno-exceptions"
-    COMPILE_DEFINITIONS
-        _HAS_EXCEPTIONS=0 # MSVC stdlib
-        _STLP_NO_EXCEPTIONS # STLPort
-    LINK_LIBRARIES Boost::range
+boost_lexical_cast_add_test_impl(lexical_cast_no_exceptions_test no_exceptions_test.cpp "Boost::container;Boost::range")
+target_include_directories(lexical_cast_no_exceptions_test PRIVATE ../include)
+target_compile_definitions(lexical_cast_no_exceptions_test
+    PRIVATE
+      _HAS_EXCEPTIONS=0 # MSVC stdlib
+      _STLP_NO_EXCEPTIONS # STLPort
 )
+if(MSVC)
+    target_compile_definitions(lexical_cast_no_exceptions_test PRIVATE BOOST_NO_EXCEPTIONS)
+endif()
+target_compile_options(lexical_cast_no_exceptions_test PRIVATE "-fno-exceptions")
 
-boost_test(TYPE run SOURCES iterator_range_test.cpp LINK_LIBRARIES Boost::range)
-boost_test(TYPE run SOURCES string_view_test.cpp LINK_LIBRARIES Boost::utility)
-boost_test(TYPE run SOURCES arrays_test.cpp LINK_LIBRARIES Boost::array)
-boost_test(TYPE run SOURCES integral_types_test.cpp LINK_LIBRARIES Boost::type_traits)
-boost_test(TYPE run SOURCES stream_detection_test.cpp)
-boost_test(TYPE run SOURCES stream_traits_test.cpp LINK_LIBRARIES Boost::array Boost::range Boost::utility)
+boost_lexical_cast_add_test(iterator_range_test Boost::range)
+boost_lexical_cast_add_test(string_view_test Boost::utility)
+boost_lexical_cast_add_test(arrays_test Boost::array)
+boost_lexical_cast_add_test(integral_types_test Boost::type_traits)
+boost_lexical_cast_add_test(stream_detection_test "")
+boost_lexical_cast_add_test(stream_traits_test "Boost::array;Boost::range;Boost::utility")
 
-boost_test(TYPE compile-fail SOURCES to_pointer_test.cpp)
-boost_test(TYPE compile-fail SOURCES from_volatile.cpp)
-boost_test(TYPE run SOURCES filesystem_test.cpp LINK_LIBRARIES Boost::filesystem)
-boost_test(TYPE run SOURCES try_lexical_convert.cpp)
+boost_lexical_cast_add_test(filesystem_test Boost::filesystem)
+boost_lexical_cast_add_test(try_lexical_convert "")
 
 file(GLOB EXAMPLE_FILES "../example/*.cpp")
 foreach (testsourcefile ${EXAMPLE_FILES})
-    boost_test(TYPE run SOURCES ${testsourcefile} LINK_LIBRARIES Boost::variant Boost::date_time)
+    get_filename_component(testname ${testsourcefile} NAME_WE)
+    boost_lexical_cast_add_test_impl(lexical_cast_example_${testname} ${testsourcefile} "Boost::variant;Boost::date_time")
 endforeach()

test/Jamfile.v2

@@ -1,5 +1,5 @@
 # Copyright (C) 2001-2003 Douglas Gregor
-# Copyright (C) Antony Polukhin, 2011-2024
+# Copyright Antony Polukhin, 2011-2026.
 #
 # Distributed under the Boost Software License, Version 1.0. (See accompanying
 # file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

test/abstract_test.cpp

@@ -3,7 +3,7 @@
 //  See http://www.boost.org for most recent version, including documentation.
 //
 //  Copyright Sergey Shandar 2005, Alexander Nasonov, 2007.
-//  Copyright Antony Polukhin, 2023-2025.
+//  Copyright Antony Polukhin, 2023-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -12,10 +12,10 @@
 // Test abstract class. Bug 1358600:
 // http://sf.net/tracker/?func=detail&aid=1358600&group_id=7586&atid=107586
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 class A
 {
 public:

test/appveyor.yml

@@ -2,7 +2,7 @@
 # subject to the Boost Software License, Version 1.0. (See accompanying
 # file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 #
-# Copyright Antony Polukhin, 2016-2025.
+# Copyright Antony Polukhin, 2016-2026.
 
 #
 # See https://svn.boost.org/trac/boost/wiki/TravisCoverals for description of this file

test/arrays_test.cpp

@@ -2,18 +2,18 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
 #include <boost/array.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 using namespace boost;
 
 #if !defined(BOOST_NO_CXX11_CHAR16_T) && !defined(BOOST_NO_CXX11_UNICODE_LITERALS) && !defined(_LIBCPP_VERSION) && !defined(BOOST_MSVC)
@@ -61,7 +61,7 @@ static void testing_template_array_output_on_spec_value(T val)
         BOOST_TEST_THROWS(lexical_cast<sshort_arr_type>(val), boost::bad_lexical_cast);
     }
 
-#if !defined(BOOST_NO_STRINGSTREAM) && !defined(BOOST_NO_STD_WSTRING)
+#if !defined(BOOST_NO_STRINGSTREAM) && !defined(BOOST_NO_STD_WSTRING) && !defined(_LIBCPP_VERSION)
     typedef ArrayT<wchar_t, 300> warr_type;
     typedef ArrayT<wchar_t, 3> wshort_arr_type;
     std::wstring wethalon(L"100");
@@ -156,7 +156,7 @@ static void testing_template_array_output_on_char_value()
         BOOST_TEST_THROWS(lexical_cast<sshort_arr_type>(val), boost::bad_lexical_cast);
     }
 
-#if !defined(BOOST_NO_STRINGSTREAM) && !defined(BOOST_NO_STD_WSTRING)
+#if !defined(BOOST_NO_STRINGSTREAM) && !defined(BOOST_NO_STD_WSTRING) && !defined(_LIBCPP_VERSION)
     typedef ArrayT<wchar_t, 4> warr_type;
     typedef ArrayT<wchar_t, 3> wshort_arr_type;
     std::wstring wethalon(L"100");
@@ -238,11 +238,13 @@ static void testing_template_array_output_on_char_value()
 
 void testing_boost_array_output_conversion()
 {
+#ifndef _LIBCPP_VERSION
     testing_template_array_output_on_char_value<boost::array>();
     testing_template_array_output_on_spec_value<boost::array>(100);
     testing_template_array_output_on_spec_value<boost::array>(static_cast<short>(100));
     testing_template_array_output_on_spec_value<boost::array>(static_cast<unsigned short>(100));
     testing_template_array_output_on_spec_value<boost::array>(static_cast<unsigned int>(100));
+#endif
 }
 
 void testing_std_array_output_conversion()
@@ -344,7 +346,10 @@ static void testing_generic_array_input_conversion()
 
 void testing_boost_array_input_conversion()
 {
+#ifndef _LIBCPP_VERSION
     testing_generic_array_input_conversion<boost::array>();
+#endif
+    BOOST_TEST(true);
 }
 
 void testing_std_array_input_conversion()

test/cmake_subdir_test/CMakeLists.txt

@@ -0,0 +1,80 @@
+# Copyright  (c) 2016-2025 Antony Polukhin
+# Copyright  (c) 2025-2026 Fedor Osetrov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+cmake_minimum_required(VERSION 3.5...4.0)
+
+project(lexical_cast_subdir_test LANGUAGES CXX)
+
+set(deps
+
+# Library dependencies
+config
+container
+core
+throw_exception
+
+# Test dependencies
+algorithm
+array
+align
+assert
+atomic
+bind
+compat
+concept_check
+container_hash
+conversion
+date_time
+describe
+detail
+exception
+filesystem
+function
+function_types
+functional
+fusion
+integer
+intrusive
+io
+iterator
+move
+mp11
+mpl
+numeric/conversion
+optional
+predef
+preprocessor
+range
+regex
+scope
+smart_ptr
+static_assert
+system
+test
+tokenizer
+tuple
+type_index
+type_traits
+typeof
+unordered
+utility
+variant
+variant2
+winapi
+)
+
+foreach(dep IN LISTS deps)
+    add_subdirectory(../../../${dep} boostorg/${dep})
+endforeach()
+
+enable_testing()
+add_subdirectory(../../ boostorg/lexical_cast)
+
+if (BOOST_USE_MODULES)
+    add_executable(boost_lexical_cast_module_usage ../modules/usage_sample.cpp)
+    target_link_libraries(boost_lexical_cast_module_usage PRIVATE Boost::lexical_cast)
+    add_test(NAME boost_lexical_cast_module_usage COMMAND boost_lexical_cast_module_usage)
+endif()
+

test/containers_test.cpp

@@ -2,17 +2,17 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 #include <boost/container/string.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 using namespace boost;
 
 void testing_boost_containers_basic_string()

test/empty_input_test.cpp

@@ -2,21 +2,22 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
 #include <boost/range/iterator_range.hpp>
 
-#include "escape_struct.hpp"
-
 #include <boost/core/lightweight_test.hpp>
 
 #include <vector>
 
+#include <boost/lexical_cast.hpp>
+
+#include "escape_struct.hpp"
+
 using namespace boost;
 
 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)

test/escape_struct.hpp

@@ -1,6 +1,6 @@
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2020.
+//  Copyright Antony Polukhin, 2020-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file

test/filesystem_test.cpp

@@ -2,7 +2,7 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2013-2025.
+//  Copyright Antony Polukhin, 2013-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -10,11 +10,11 @@
 //
 // Test lexical_cast usage with long filesystem::path. Bug 7704.
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 #include <boost/filesystem/path.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 void test_filesystem()
 {
     boost::filesystem::path p;

test/float_types_test.cpp

@@ -2,24 +2,27 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#ifndef BOOST_LEXICAL_CAST_DETAIL_TEST_ON_OLD
-#include <boost/lexical_cast.hpp>
-#else
-// Make sure that tests work the same way on non-optimized version
-#include "lexical_cast_old.hpp"
-#endif
-
+#include <sstream>
 #include <type_traits>
 
 #include <boost/cstdint.hpp>
 #include <boost/core/lightweight_test.hpp>
+
+#ifndef BOOST_LEXICAL_CAST_DETAIL_TEST_ON_OLD
 #include <boost/lexical_cast/detail/type_traits.hpp>
+#include <boost/lexical_cast.hpp>
+#else
+// Make sure that tests work the same way on non-optimized version
+#include "lexical_cast_old.hpp"
+#include <boost/lexical_cast/detail/type_traits.hpp>
+#endif
+
 
 #ifndef BOOST_TEST_CLOSE_FRACTION
 // Naiive, but works for most tests in this file 
@@ -303,7 +306,7 @@ void test_float_typess_for_overflows()
     BOOST_TEST_THROWS(lexical_cast<test_t>("1"+s_max_value), bad_lexical_cast);
     BOOST_TEST_THROWS(lexical_cast<test_t>("9"+s_max_value), bad_lexical_cast);
 #endif
-
+#if !(defined(_LIBCPP_VERSION) && defined(BOOST_LEXICAL_CAST_DETAIL_TEST_ON_OLD))
     if ( std::is_same<test_t,float>::value )
     {
         BOOST_TEST_THROWS(lexical_cast<test_t>( (std::numeric_limits<double>::max)() ), bad_lexical_cast);
@@ -339,6 +342,7 @@ void test_float_typess_for_overflows()
                 <= (std::numeric_limits<long double>::min)() / 2 + std::numeric_limits<test_t>::epsilon()
         );
     }
+#endif
 }
 
 #undef CHECK_CLOSE_ABS_DIFF

test/from_volatile.cpp

@@ -1,4 +1,4 @@
-//  Copyright Antony Polukhin, 2013-2025.
+//  Copyright Antony Polukhin, 2013-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file

test/implicit_convert.cpp

@@ -1,13 +1,13 @@
-//  Copyright Antony Polukhin, 2023-2025.
+//  Copyright Antony Polukhin, 2023-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 struct oops {
     operator int () const {
         return 41;

test/inf_nan_test.cpp

@@ -2,7 +2,7 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -10,12 +10,12 @@
 
 #include <type_traits>
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/cmath.hpp>
 
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
 #define BOOST_LCAST_NO_WCHAR_T
 #endif

test/integral_types_test.cpp

@@ -4,7 +4,7 @@
 //
 //  Copyright Terje Sletteb and Kevlin Henney, 2005.
 //  Copyright Alexander Nasonov, 2006.
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -19,8 +19,6 @@
 //
 #define _SCL_SECURE_NO_WARNINGS
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/cstdint.hpp>
 
 #include <boost/core/lightweight_test.hpp>
@@ -29,10 +27,13 @@
 
 #include <boost/type_traits/integral_promotion.hpp>
 #include <string>
+#include <sstream>
 #include <vector>
 #include <memory>
 #include <type_traits>
 
+#include <boost/lexical_cast.hpp>
+
 #if (defined(BOOST_HAS_LONG_LONG) || defined(BOOST_HAS_MS_INT64)) \
     && !(defined(BOOST_MSVC) && BOOST_MSVC < 1300)
 #define LCAST_TEST_LONGLONG

test/iterator_range_test.cpp

@@ -2,19 +2,19 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/range/iterator_range.hpp>
 
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 using namespace boost;
 
 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
@@ -136,7 +136,7 @@ void test_it_range_using_char(CharT* one, CharT* eleven)
 #endif
     BOOST_TEST_EQ(lexical_cast<class_with_user_defined_sream_operators>(crng2), 1);
 
-#ifndef BOOST_LCAST_NO_WCHAR_T
+#if !defined(BOOST_LCAST_NO_WCHAR_T) && !defined(_LIBCPP_VERSION)
     BOOST_TEST(lexical_cast<std::wstring>(rng1) == L"1");
     BOOST_TEST(lexical_cast<std::wstring>(crng1) == L"1");
     BOOST_TEST(lexical_cast<std::wstring>(rng2) == L"1");
@@ -191,7 +191,7 @@ void test_signed_char_iterator_ranges()
 
 void test_wchar_iterator_ranges()
 {
-#ifndef BOOST_LCAST_NO_WCHAR_T
+#if !defined(BOOST_LCAST_NO_WCHAR_T) && !defined(_LIBCPP_VERSION)
     typedef wchar_t test_char_type;
     test_char_type data1[] = L"1";
     test_char_type data2[] = L"11";

test/lexical_cast_old.hpp

@@ -1,6 +1,6 @@
 // Copyright Kevlin Henney, 2000-2005.
 // Copyright Alexander Nasonov, 2006-2010.
-// Copyright Antony Polukhin, 2011-2025.
+// Copyright Antony Polukhin, 2011-2026.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -34,7 +34,6 @@
 #include <cstdio>
 #include <type_traits>
 #include <boost/limits.hpp>
-#include <boost/detail/lcast_precision.hpp>
 #include <boost/config/workaround.hpp>
 
 #ifdef BOOST_NO_STRINGSTREAM
@@ -43,6 +42,10 @@
 #include <sstream>
 #endif
 
+#if defined(BOOST_USE_MODULES)
+#undef BOOST_USE_MODULES
+#endif
+#include <boost/lexical_cast/detail/lcast_precision.hpp>
 #include <boost/lexical_cast/bad_lexical_cast.hpp>
 #include <boost/lexical_cast/detail/widest_char.hpp>
 

test/lexical_cast_test.cpp

@@ -4,7 +4,7 @@
 //
 //  Copyright Terje Sletteb and Kevlin Henney, 2005.
 //  Copyright Alexander Nasonov, 2006.
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -19,8 +19,6 @@
 //
 #define _SCL_SECURE_NO_WARNINGS
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/cstdint.hpp>
 
 #include <boost/core/lightweight_test.hpp>
@@ -31,6 +29,8 @@
 #include <algorithm> // std::transform
 #include <memory>
 
+#include <boost/lexical_cast.hpp>
+
 #if (defined(BOOST_HAS_LONG_LONG) || defined(BOOST_HAS_MS_INT64)) \
     && !(defined(BOOST_MSVC) && BOOST_MSVC < 1300)
 #define LCAST_TEST_LONGLONG
@@ -528,8 +528,10 @@ void test_char16_conversions()
 // There's no std::ctype<char16_t> in Xcode_15.0.1
 #if !defined(BOOST_NO_CXX11_CHAR16_T) && !defined(BOOST_NO_CXX11_UNICODE_LITERALS) && !defined(__APPLE__)
     BOOST_TEST(u"100" == lexical_cast<std::u16string>(u"100"));
+#if !defined(_LIBCPP_VERSION) // libc++ also does not have std::ctype<char16_t>
     BOOST_TEST(u"1" == lexical_cast<std::u16string>(u'1'));
 #endif
+#endif
 }
 
 void test_char32_conversions()
@@ -537,8 +539,10 @@ void test_char32_conversions()
 // There's no std::ctype<char32_t> in Xcode_15.0.1
 #if !defined(BOOST_NO_CXX11_CHAR32_T) && !defined(BOOST_NO_CXX11_UNICODE_LITERALS) && !defined(__APPLE__)
     BOOST_TEST(U"100" == lexical_cast<std::u32string>(U"100"));
+#if !defined(_LIBCPP_VERSION) // libc++ also does not have std::ctype<char32_t>
     BOOST_TEST(U"1" == lexical_cast<std::u32string>(U'1'));
 #endif
+#endif
 }
 
 void test_getting_pointer_to_function()

test/loopback_test.cpp

@@ -3,7 +3,7 @@
 //  See http://www.boost.org for most recent version, including documentation.
 //
 //  Copyright Alexander Nasonov, 2006.
-//  Copyright Antony Polukhin, 2023-2025.
+//  Copyright Antony Polukhin, 2023-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -12,10 +12,10 @@
 //  Test round-tripping conversion FPT -> string -> FPT,
 //  where FPT is Floating Point Type.
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 #if (defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__NetBSD__) \
    || (defined(__hppa) && !defined(__OpenBSD__)) || (defined(__NO_LONG_DOUBLE_MATH) && (DBL_MANT_DIG != LDBL_MANT_DIG))) \
    || defined(__MINGW64__)

test/no_exceptions_test.cpp

@@ -2,7 +2,7 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -16,12 +16,16 @@
 #pragma warning(disable: 4097 4100 4121 4127 4146 4244 4245 4511 4512 4701 4800)
 #endif
 
-#include <boost/lexical_cast.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/range/iterator_range.hpp>
 
 #include <cstdlib>
 
+#if defined(BOOST_USE_MODULES)
+#undef BOOST_USE_MODULES
+#endif
+#include <boost/lexical_cast.hpp>
+
 #include "escape_struct.hpp"
 
 #ifndef BOOST_NO_EXCEPTIONS

test/no_locale_test.cpp

@@ -2,14 +2,12 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 #include <boost/range/iterator_range.hpp>
 
@@ -17,6 +15,8 @@
 
 #include <vector>
 
+#include <boost/lexical_cast.hpp>
+
 using namespace boost;
 
 // Testing compilation and some basic usage with BOOST_NO_STD_LOCALE

test/noncopyable_test.cpp

@@ -3,7 +3,7 @@
 //  See http://www.boost.org for most recent version, including documentation.
 //
 //  Copyright Alexander Nasonov, 2007.
-//  Copyright Antony Polukhin, 2023-2025.
+//  Copyright Antony Polukhin, 2023-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
@@ -11,11 +11,12 @@
 //
 //  Test that Source can be non-copyable.
 
-#include <boost/lexical_cast.hpp>
 #include <boost/core/noncopyable.hpp>
 
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 class Noncopyable : private boost::noncopyable
 {
 public:

test/pointers_test.cpp

@@ -2,16 +2,18 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
+#include <sstream>
+
+#include <boost/lexical_cast.hpp>
+
 #if defined(BOOST_NO_STRINGSTREAM)
             typedef std::strstream ss_t;
 #else

test/stream_detection_test.cpp

@@ -2,19 +2,19 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
 #include <iostream>
 #include <type_traits>
 
+#include <boost/lexical_cast.hpp>
+
 
 ///////////////////////// char streamable classes ///////////////////////////////////////////
 

test/stream_traits_test.cpp

@@ -1,9 +1,12 @@
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
+#if defined(BOOST_USE_MODULES)
+#undef BOOST_USE_MODULES
+#endif
 #include <boost/lexical_cast/detail/converter_lexical.hpp>
 
 #include <boost/core/lightweight_test.hpp>

test/string_view_test.cpp

@@ -2,15 +2,13 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2012-2025.
+//  Copyright Antony Polukhin, 2012-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
 
-#include <boost/lexical_cast.hpp>
-
 #include <boost/utility/string_view.hpp>
 
 #ifndef BOOST_NO_CXX17_HDR_STRING_VIEW
@@ -19,6 +17,8 @@
 
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast.hpp>
+
 
 template <class StringView>
 void test_string_view_conversion() {

test/to_pointer_test.cpp

@@ -2,7 +2,7 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2013-2025.
+//  Copyright Antony Polukhin, 2013-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file

test/try_lexical_convert.cpp

@@ -2,16 +2,16 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2014-2025.
+//  Copyright Antony Polukhin, 2014-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
-#include <boost/lexical_cast/try_lexical_convert.hpp>
-
 #include <boost/core/lightweight_test.hpp>
 
+#include <boost/lexical_cast/try_lexical_convert.hpp>
+
 using namespace boost::conversion;
 
 void try_uncommon_cases()

test/typedefed_wchar_test.cpp

@@ -2,7 +2,7 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file

test/typedefed_wchar_test_runtime.cpp

@@ -2,7 +2,7 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file

test/vc8_bug_test.cpp

@@ -12,12 +12,14 @@
 // implementation has changed and it does not use stringstream for casts
 // to integral types
 
-#include <boost/lexical_cast.hpp>
 #include <boost/cstdint.hpp>
 
 #include <boost/core/lightweight_test.hpp>
 
 #include <string>
+#include <sstream>
+
+#include <boost/lexical_cast.hpp>
 
 #ifdef BOOST_MSVC
 # pragma warning(disable: 4127) // conditional expression is constant

test/wchars_test.cpp

@@ -2,15 +2,20 @@
 //
 //  See http://www.boost.org for most recent version, including documentation.
 //
-//  Copyright Antony Polukhin, 2011-2025.
+//  Copyright Antony Polukhin, 2011-2026.
 //
 //  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt).
 
+#include <boost/core/lightweight_test.hpp>
+
 #include <boost/lexical_cast.hpp>
 
-#include <boost/core/lightweight_test.hpp>
+#if defined(BOOST_USE_MODULES)
+#undef BOOST_USE_MODULES
+#endif
+#include <boost/lexical_cast/detail/lcast_char_constants.hpp>
 
 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
 #define BOOST_LCAST_NO_WCHAR_T