python: add nvme.i consistency check and fix violations

Background

The SWIG interface file libnvme/libnvme/nvme.i exposes libnvme's internal C structs to Python. Struct fields are meant to be accessed through getter/setter accessor functions (e.g., libnvme_ctrl_get_name()) rather than by direct struct member access (e.g., ctrl->name). This is enforced through a combination of SWIG mechanisms:

• Fields placed inside an inline %extend {} block cause SWIG to generate calls to the accessor functions instead of accessing the struct member directly.
• Fields annotated !accessors:readonly in the private headers must be declared %immutable in nvme.i to prevent SWIG from generating a setter.

Keeping nvme.i consistent with the accessor annotations in private.h and private-fabrics.h is error-prone and easy to get wrong. Every time a new field is added to a !generate-accessors struct, or an annotation changes, nvme.i must be updated in sync — and there was previously no automated check to catch mistakes.

What this PR adds

libnvme/tools/check-nvme-i-consistency.py

A new static analysis script that validates nvme.i against the accessor annotations in the private headers. It is pure Python (stdlib only) and performs no compilation — it parses source files with regex + brace counting.

The script enforces the following rules:

The script bridges from two sources:

• nvme-swig-accessors.i — auto-generated #define bridges for all accessor-generated functions
• The %{ ... %} block in nvme.i — hand-written bridges for hand-written functions

The script exits with a non-zero status when errors are found (causing the meson test to fail) and with zero when only warnings are present. Errors are printed to stderr so they appear in meson-logs/testlog.txt on failure.

Meson test registration

The check is registered as a meson test in libnvme/libnvme/meson.build inside the if want_python block. It does not depend on the built SWIG module (pynvme_clib) — it is pure static analysis and runs quickly.

17/67 libnvme - check-nvme-i-consistency   OK   0.09s

Fixes to libnvme/libnvme/nvme.i

The new check immediately found 12 Rule 2 violations — fields with auto-generated getters that were exposed as direct struct members instead of through %extend {}. These have been fixed:

Stale comments on cntrltype, dctype, and discovered claiming "no getter method in libnvme.map" have been removed — those getters exist and are correctly mapped in nvme-swig-accessors.i.

Testing

meson test -C .build 'libnvme - check-nvme-i-consistency'

The test passes with zero errors. Remaining warnings (Check 6, Check 7) reflect known intentional patterns in the current nvme.i and do not block the build.