Feature or enhancement

sysconfig should export all the information required to build extensions.

Pitch

The new API should try to expose the information in a compiler-agnostic way.

Information to expose

• Python version
  • currently: sys.version_info
• Interpreter version
  • currently: sys.implementation
• Extension suffixes
  • definition: See PEP 3149
    • consideration: PEP 3149 only defines the names for POSIX
      • Windows and other platforms still seem to follow it mostly (refer to packaging.tags's implementation)
      • Windows
    • design: The API should identify the different extensions types (interpreter, stable abi, none)
  • currently: importlib.machinery.EXTENSION_SUFFIXES, sysconfig.get_config_var('EXT_SUFFIX'), sysconfig.get_config_var('SHLIB_SUFFIX')
• Is a shared libpython available? What's its name? Location?
  • definition: Yes if built with --enable-shared
  • currently:
    • (available?) bool(sysconfig.get_config_var('LDLIBRARY'))
    • (name?) sysconfig.get_config_var('LDLIBRARY')
    • (location?) sysconfig.get_config_var('LIBDIR')
• Is a static libpython available? What's its name? Location?
  • definition: Yes unless built with --without-static-libpython
  • currently:
    • (available?) bool(sysconfig.get_config_var('LIBRARY'))
    • (name?) sysconfig.get_config_var('LIBRARY')
    • (location?) sysconfig.get_config_var('LIBDIR')
• Should extensions link against libpython?
  • definition: Yes on Android and Cygwin, no everywhere else (see extension built with a shared python cannot be loaded with a static python #65735)
  • currently: bool(sysconfig.get_config_var('LIBPYTHON'))
• Is it a debug build?
  • definition: Yes if built with --with-pydebug
  • currently: bool(sysconfig.get_config_var('Py_DEBUG'))
• C flags needed when using the C API
  • definition:
    • -fwrapv (until Enable -fstrict-overflow #96821)
      • Currently, we have unsafe code, and for a lack of a better option we assume it made into C macros, so extensions that use the C API should use -fwrapv.
• what else? please comment...

"definition" sections list the answer, if a question, or the value(s) of the item. "currently" sections list the current way of fetching the information.

This is list is a work in progress. Currently, we need to gather all the information that is required to build extensions. If you see anything that's missing, please comment!

Previous discussion

https://discuss.python.org/t/building-extensions-modules-in-a-post-distutils-world/23938
https://discuss.python.org/t/what-information-is-useful-to-know-statically-about-an-interpreter/25563
https://gregoryszorc.com/docs/python-build-standalone/20230116/distributions.html

New sysconfig API meta-issue: GH-103480