How to support c++ 20 module name mangling when Interfacing to C++?

[pengybhnu]

I reference cpp_interface，calling C++ Global Functions from D but link error when compile c++ source in c++20 module syntax as library.
app.d source file content

module app ;
import std.stdio;
extern (C++,dmd) int foo(int i, int j, int k);

void main()
{
    auto x = foo(1, 2, 3);
    writeln(x);
}

compile foo.cppm with cmake , generate libfoo.so

add_library(geo SHARED)
target_sources(geo PUBLIC
    FILE_SET CXX_MODULES FILES 
    ${CMAKE_SOURCE_DIR}/src/geo.cppm
)

// foo.cppm
module;
#include <iostream>
export module Test;
using namespace std;
export namespace detail {

int foo(int i, int j, int k) {
  cout << "i = " << i << endl;
  cout << "j = " << j << endl;
  cout << "k = " << k << endl;

  return 7;
}
} // namespace detail
export namespace dmd {

int foo(int i, int j, int k) {
  cout << "i = " << i + 100 << endl;
  cout << "j = " << j + 200 << endl;
  cout << "k = " << k + 300 << endl;

  return 20;
}
} // namespace detail

when use dub build to link ,gave the error

undefined reference to `dmd::foo(int, int, int)'
clang-18: error: linker command failed with exit code 1 (use -v to see invocation)
Error: undefined reference to `dmd::foo(int, int, int)`
       perhaps a library needs to be added with the `-L` flag or `pragma(lib, ...)`

dump name symbol

╰─ llvm-nm-18 -C build/libgeo.so |grep foo
0000000000001260 T dmd::foo@Test(int, int, int)
00000000000011b0 T detail::foo@Test(int, int, int)

[Lars-Kristiansen]

As a workaround you might try to see if pragma(mangle, <the_right_thing_as_a_string>) is of any help. But clearly even if it appears that this works, that does not scale, i.e not a good general solution.

[pengybhnu]

As a workaround you might try to see if pragma(mangle, <the_right_thing_as_a_string>) is of any help. But clearly even if it appears that this works, that does not scale, i.e not a good general solution.

thanks, it works! may be better if extern (C++,<namespace>,<c++ module name>) syntax supported by compiler

  pragma(mangle, "_ZN3dmdW4Test3fooEiii")
  extern (C++) int foo(int i, int j, int k);

llvm-nm-18 build/libgeo.so |grep foo                     
00000000000012e0 T _ZN3dmdW4Test3fooEiii
0000000000001230 T _ZN6detailW4Test3fooEiii