C++ 20 Modules Support

[sdykae]

Modules intellisense and completion not working even when cmake compiles
llvm compiled from https://github.com/mathstuf/llvm-project/tree/p1689r5-csd
according cmake reference https://gitlab.kitware.com/cmake/cmake/-/issues/18355

Compilation works and executable but intellisense

main.cpp

import Hello;
int main() { hello(); }

hello.cppm

module;
#include <iostream>
export module Hello;
export void hello() {
  std::cout << "Hello World!\n";
}

CMakeList.txt

cmake_minimum_required(VERSION 3.25.2`)
project(app)
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

set(CMAKE_C_COMPILER /Users/sdykae/development/llvm-project-p1689r5-csd/build/bin/clang)
set(CMAKE_CXX_COMPILER /Users/sdykae/development/llvm-project-p1689r5-csd/build/bin/clang++)

set(CMAKE_LDFLAGS "-L/Users/sdykae/development/llvm-project-p1689r5-csd/build/lib")
SET(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -fuse-ld=/Users/sdykae/development/llvm-project-p1689r5-csd/build/bin/ld64.lld")
SET(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -Wl,-L/Users/sdykae/development/llvm-project-p1689r5-csd/build/lib")
set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -std=c++2b -fexperimental-library -stdlib=libc++" )
message(STATUS "CMAKE_CXX_FLAGS: ${CMAKE_CXX_FLAGS}")
set(CMAKE_OSX_DEPLOYMENT_TARGET "10.15")
set(CMAKE_OSX_ARCHITECTURES "x86_64")

set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "2182bf5c-ef0d-489a-91da-49dbc3090d2a")
set(CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP 1)

string(CONCAT CMAKE_EXPERIMENTAL_CXX_SCANDEP_SOURCE
  "/Users/sdykae/development/llvm-project-p1689r5-csd/build/bin/clang-scan-deps"
  " -format=p1689 --p1689-targeted-file-name=<SOURCE> --p1689-targeted-output=<OBJECT> "
  " --p1689-makeformat-output=<DEP_FILE>"
  " --"
  " <DEFINES> <INCLUDES> <FLAGS> -x c++ <SOURCE>"
  " -MT <DYNDEP_FILE> -MD"
  " > <DYNDEP_FILE>")

set(CMAKE_EXPERIMENTAL_CXX_MODULE_MAP_FORMAT "clang")
set(CMAKE_EXPERIMENTAL_CXX_MODULE_MAP_FLAG "@<MODULE_MAP_FILE>")
set(CMAKE_CXX_EXTENSIONS OFF)
set(source_files main.cc )

add_executable(${PROJECT_NAME})
target_sources(${PROJECT_NAME}
  PRIVATE
    main.cpp
  PRIVATE
    FILE_SET CXX_MODULES
      # BASE_DIRS
      #   "${CMAKE_CURRENT_SOURCE_DIR}"
      FILES
        hello.cppm
)

target_compile_features(${PROJECT_NAME} PUBLIC cxx_std_20)

If you can, provide a minimal chunk of code that shows the problem (either inline, or attach it if larger).

Logs
Please attach the clangd log from the "Output" window if you can.
If possible, run with --log=verbose - note that the logs will include the contents of open files!

System information
Clangd version (from the log, or clangd --version):

clangd extension version: 16.0.0
Operating system: osx ventura 13.1

[HighCommander4]

Please see #1293 for the current status of modules support in clangd

[kadircet]

moving to clangd and closing as duplicate