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[libc++][doc] Updates module information. #75003

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Dec 12, 2023
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[libc++][doc] Updates module information. #75003

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39 changes: 22 additions & 17 deletions libcxx/docs/Modules.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -38,8 +38,8 @@ What works
~~~~~~~~~~

* Building BMIs
* Running tests using the ``std`` module
* Using the ``std`` module in external projects
* Running tests using the ``std`` and ``std.compat`` module
* Using the ``std`` and ``std.compat`` module in external projects
* The following "parts disabled" configuration options are supported

* ``LIBCXX_ENABLE_LOCALIZATION``
Expand All @@ -65,10 +65,9 @@ Some of the current limitations
* Requires CMake 3.26 for C++23 support
* Requires CMake 3.27 for C++26 support
* Requires Ninja 1.11
* Requires a recent Clang 17
* Requires Clang 17
* The path to the compiler may not be a symlink, ``clang-scan-deps`` does
not handle that case properly
* Only C++23 and C++26 are tested
* Libc++ is not tested with modules instead of headers
* The module ``.cppm`` files are not installed
* Clang supports modules using GNU extensions, but libc++ does not work using
Expand Down Expand Up @@ -127,9 +126,13 @@ This is a small sample program that uses the module ``std``. It consists of a

.. code-block:: cpp

import std;
import std; // When importing std.compat it's not needed to import std.
import std.compat;

int main() { std::cout << "Hello modular world\n"; }
int main() {
std::cout << "Hello modular world\n";
::printf("Hello compat modular world\n");
}

.. code-block:: cmake

Expand All @@ -142,7 +145,6 @@ This is a small sample program that uses the module ``std``. It consists of a
# Set language version used
#

# At the moment only C++23 is tested.
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED YES)
# Libc++ doesn't support compiler extensions for modules.
Expand All @@ -153,12 +155,16 @@ This is a small sample program that uses the module ``std``. It consists of a
#

# This is required to write your own modules in your project.
if(CMAKE_VERSION VERSION_LESS "3.27.0")
set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "2182bf5c-ef0d-489a-91da-49dbc3090d2a")
if(CMAKE_VERSION VERSION_LESS "3.28.0")
if(CMAKE_VERSION VERSION_LESS "3.27.0")
set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "2182bf5c-ef0d-489a-91da-49dbc3090d2a")
else()
set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "aa1f7df0-828a-4fcd-9afc-2dc80491aca7")
endif()
set(CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP 1)
else()
set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "aa1f7df0-828a-4fcd-9afc-2dc80491aca7")
cmake_policy(VERSION 3.28)
endif()
set(CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP 1)

#
# Import the modules from libc++
Expand All @@ -169,18 +175,16 @@ This is a small sample program that uses the module ``std``. It consists of a
std
URL "file://${LIBCXX_BUILD}/modules/c++/v1/"
DOWNLOAD_EXTRACT_TIMESTAMP TRUE
SYSTEM
)
FetchContent_GetProperties(std)
if(NOT std_POPULATED)
FetchContent_Populate(std)
add_subdirectory(${std_SOURCE_DIR} ${std_BINARY_DIR} EXCLUDE_FROM_ALL)
endif()
FetchContent_MakeAvailable(std)

#
# Adjust project compiler flags
#

add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fprebuilt-module-path=${CMAKE_BINARY_DIR}/_deps/std-build/CMakeFiles/std.dir/>)
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fprebuilt-module-path=${CMAKE_BINARY_DIR}/_deps/std-build/CMakeFiles/std.compat.dir/>)
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-nostdinc++>)
# The include path needs to be set to be able to use macros from headers.
# For example from, the headers <cassert> and <version>.
Expand All @@ -194,8 +198,9 @@ This is a small sample program that uses the module ``std``. It consists of a
add_link_options($<$<COMPILE_LANGUAGE:CXX>:-nostdlib++>)
add_link_options($<$<COMPILE_LANGUAGE:CXX>:-L${LIBCXX_BUILD}/lib>)
add_link_options($<$<COMPILE_LANGUAGE:CXX>:-Wl,-rpath,${LIBCXX_BUILD}/lib>)
# Linking against std is required for CMake to get the proper dependencies
# Linking against the standard c++ library is required for CMake to get the proper dependencies.
link_libraries(std c++)
link_libraries(std.compat c++)

#
# Add the project
Expand Down