EOF to stdin when launching process asynchronously on macOS

Start by compiling and running the supplied C++ reproducer on macOS 15.6.1 with Boost 1.89.0; trigger r and observe std::cin after /bin/ls exits. Inspect the interaction between bp::process_stdio{nullptr}, asynchronous launch, and the parent stdin state. Done means subprocess completion no longer causes the input loop to see EOF while the reproducer still reports the child exit code.

On macOS 15.6.1 M3 the program below exits due to EOF flag being raised on std::cin after subprocess finishes.

#include <boost/process.hpp>
#include <boost/asio.hpp>
#include <cstdio>
#include <string>
#include <iostream>
#include <future>
#include <vector>

namespace asio = boost::asio;
namespace bp = boost::process::v2;

void runCommand(const std::string &cmd);

int main(int argc, char *argv[]) {
  std::vector<std::future<void>> tasks;
  std::string line;
  while(true) {
    if (!std::getline(std::cin, line)) {
      if (std::cin.eof()) {
        break;
      }
      std::printf("Error reading input?\n");
      std::cin.clear();
      continue;
    }

    if (line == "r") {
      tasks.push_back(std::async(std::launch::async, []() {
        runCommand("/bin/ls");
      }));
    }
  }

  return 0;
}

void runCommand(const std::string &cmd) {
  try {
    std::printf("Running subprocess: %s\n", cmd.c_str());
    asio::io_context ctx;
    bp::process subProcess(ctx, cmd, {}, bp::process_stdio{nullptr});
    subProcess.wait();

    std::printf("Finished running subprocess with exit code %d\n", subProcess.exit_code());
  } catch (const std::exception &ex) {
    std::printf("Error running subprocess: %s\n", ex.what());
  }
}

Compiler

Apple clang version 17.0.0 (clang-1700.0.13.5)
Target: arm64-apple-darwin24.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Boos version (from vcpkg)

1.89.0

Example run:

boost-process git:(cpp-boost-process) ✗ ./build/main
r
Running subprocess: /bin/ls
CMakeLists.txt	README.md	build		main.cpp	vcpkg.json	vcpkg_installed
Finished running subprocess with exit code 0