From 33fb7a6bd849653445b6ae37a8c274d3de9519cc Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Fri, 2 Dec 2022 05:41:49 -0800
Subject: [PATCH] Show ODR VIOLATION DETECTED message only if
 `PYBIND11_DETAIL_TYPE_CASTER_ODR_GUARD_IMPL_DEBUG` is defined, to not clutter
 the test_gil_scoped.py output with many of these messages when
 `multiprocessing.set_start_method("forkserver")` is used.

---
 include/pybind11/detail/type_caster_odr_guard.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/pybind11/detail/type_caster_odr_guard.h b/include/pybind11/detail/type_caster_odr_guard.h
index 6dda2583a..71d074d1d 100644
--- a/include/pybind11/detail/type_caster_odr_guard.h
+++ b/include/pybind11/detail/type_caster_odr_guard.h
@@ -82,8 +82,10 @@ inline void type_caster_odr_guard_impl(const std::type_info &intrinsic_type_info
                         + reg_iter->second + "\", SourceLocation2=\"" + source_file_line_from_sloc
                         + "\"");
         if (throw_disabled) {
+#    if defined(PYBIND11_DETAIL_TYPE_CASTER_ODR_GUARD_IMPL_DEBUG)
             std::fprintf(stderr, "\nDISABLED std::system_error: %s\n", msg.c_str());
             std::fflush(stderr);
+#    endif
             type_caster_odr_violation_detected_counter()++;
         } else {
             throw std::system_error(std::make_error_code(std::errc::state_not_recoverable), msg);