Default dlopenflags inconsistent between Linux and macOS

Feature or enhancement

Proposal:

The default dlopen flags for loading extension modules specify neither RTLD_GLOBAL nor RTLD_LOCAL.

Unfortunately, the behavior when neither flag is specified differs between Linux and macOS: on Linux, RTLD_LOCAL is the default, while on macOS RTLD_GLOBAL seems to be the default.

POSIX itself is not helpful on the matter: "If neither RTLD_GLOBAL nor RTLD_LOCAL is specified, the default behavior is unspecified".

Having two different behaviors on two extremely popular platforms may make support more difficult for maintainers of complex extension modules that bundle popular third-party C/C++ libraries (here is a possible instance).

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

CPython の拡張モジュールのロードパスと、Linux、macOS、POSIX に関連する dlopen 仕様から始めます。意図された明示的なデフォルト動作を特定し、そのうえで拡張機能のロードが両方のプラットフォーム間で一貫していること、および関連する既存のカバレッジが引き続きパスすることを確認します。