Add structured version info for pyexpat

Feature or enhancement

pyexpat.EXPAT_VERSION (from XML_ExpatVersion()) and pyexpat.version_info (from XML_ExpatVersionInfo()) describe the Expat library loaded at runtime: both functions are compiled into libexpat from its XML_MAJOR_VERSION, XML_MINOR_VERSION and XML_MICRO_VERSION macros. The same macros evaluated in pyexpat.c give the version of the headers the module was built against, which is what the #if XML_COMBINED_VERSION >= ... checks in the module depend on. The two can differ when a system libexpat is used. The build-time version is not exposed to Python; it can only be inferred from which parser methods exist.

Add pyexpat.VERSION_INFO for the build-time version, and make pyexpat.version_info a named tuple.

Linked PRs

• gh-157474

Inizia in pyexpat.c, dove sono esposte le macro della versione di Expat e le API della versione a runtime. Segui le definizioni esistenti di VERSION_INFO e version_info, quindi verifica che la versione di build sia esposta separatamente e che version_info abbia un comportamento da tupla con nome. Controlla i test dell’API pyexpat, se disponibili, e conferma che entrambe le versioni vengano riportate correttamente quando differiscono.