C++ modules: 'import std;' not working
I'm using CMake 3.29.20240512-g887311f and a clang/libc++ 18.1.3 build
with the following CMakeList.txt
cmake_minimum_required(VERSION 3.29.20240416 FATAL_ERROR)
project(test VERSION 1.0.0 LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED YES)
set(CMAKE_CXX_EXTENSIONS OFF)
set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD "0e5b6991-d74f-4b3d-a41c-cf096e0b2508")
set(CMAKE_CXX_MODULE_STD ON)
configure_file(config.h.in config.h)
add_executable(main)
target_sources(main PUBLIC
main.cpp)
Running cmake -B build -S . -G Ninja -DCMAKE_CXX_COMPILER=/usr/bin/clang++ -DCMAKE_CXX_FLAGS=-stdlib=libc++ results in:
-- Configuring done (0.0s) CMake Error in CMakeLists.txt: The "CXX_MODULE_STD" property on the target "main" requires that the "__CMAKE::CXX23" target exist, but it was not provided by the toolchain. Reason:
Experimental `import std` support not enabled when detecting toolchain-- Generating done (0.0s) CMake Generate step failed. Build files cannot be regenerated correctly.