Workaround for https://github.com/RobotLocomotion/drake/issues/19680

cc_py.cc

#include <pybind11/pybind11.h>
#include <spdlog/sinks/base_sink.h>

#include "drake/common/drake_throw.h"
#include "drake/common/text_logging.h"

namespace py = pybind11;

namespace anzu {
namespace {

// No-op sink to ensure that pydrake sink does not get installed.
class noop_sink final
    : public spdlog::sinks::base_sink<spdlog::details::null_mutex> {
 public:
  noop_sink() {}

 protected:
  void sink_it_(const spdlog::details::log_msg&) final {}

  void flush_() final {}
};

void FailIfPydrakeImported() {
  py::dict modules = py::module::import("sys").attr("modules");
  if (modules.contains("pydrake")) {
    throw std::runtime_error("This module must be imported before pydrake.");
  }
}

void InstallExtraRootSink() {
  FailIfPydrakeImported();
  std::vector<std::shared_ptr<spdlog::sinks::sink> >& root_sinks =
      drake::log()->sinks();
  DRAKE_DEMAND(root_sinks.size() == 1);

  root_sinks.push_back(std::make_shared<noop_sink>());
}

PYBIND11_MODULE(no_pydrake_spdlog_sink, m) {
  InstallExtraRootSink();
}

}  // namespace
}  // namespace anzu