Adding a new C extension module to CPython's standard library
requires updating multiple files across different build systems,
which is not well documented. This adds a comprehensive guide that
covers:
- Prerequisites and design decisions (built-in vs shared)
- Step-by-step process for all platforms
- Unix/Linux: configure.ac and Setup file changes
- Windows: MSBuild .vcxproj file creation
- Testing, documentation, and cross-platform considerations
- Troubleshooting common issues with solutions
- Complete pre-submission checklist
The guide is created in a new Doc/build_system/ directory for
build-system-specific documentation that doesn't fit in the
existing extending/ or c-api/ sections.
This significantly reduces the barrier to adding new stdlib modules
and provides a template for contributors to follow.
