Documentation about debug and release build ABI compatibility is misleading

[konstin]

Documentation

The documentation on the ABI compatibility says:

cpython/Doc/using/configure.rst

Lines 908 to 911 in 7b2495e

	.. versionchanged:: 3.8
	Release builds and debug builds are now ABI compatible: defining the
	``Py_DEBUG`` macro no longer implies the ``Py_TRACE_REFS`` macro (see the
	:option:`--with-trace-refs` option).

However, this isn't ABI compatibility in the general sense, it's a one-way compatibility: An extension module built against a release build can run on a debug build, but an extension module built against a debug build may use symbols that are only defined in a debug build.

Linked PRs

• gh-146907: Clarify ABI compatibility between debug and release builds #146925
• [3.14] gh-146907: Clarify ABI compatibility between debug and release builds (GH-146925) #147971
• [3.13] gh-146907: Clarify ABI compatibility between debug and release builds (GH-146925) #147972

[encukou]

@vstinner, is this intentional, or a bug?

[vstinner]

An extension module built against a release build can run on a debug build, but an extension module built against a debug build may use symbols that are only defined in a debug build.

That's correct. The documentation should be updated to clarify that.