Re: python311 vs expat

[Adam <adam%netbsd.org@localhost>]

>>> This change broke both macOS and SunOS:
>>> 
>>> bac7175966909 (adam      2026-03-04 06:51:45 +0000  44) CONFIGURE_ARGS+=        --without-system-expat # requires expat_config.h
>>> 
>>> It means that python311 has both:
>>> 
>>> CONFIGURE_ARGS+=        --with-system-expat
>>> CONFIGURE_ARGS+=        --without-system-expat # requires expat_config.h
>>> 
>>> I don't understand how this can work.  Does this even work on NetBSD?
>>> 
>>> I think it's clearly a regression on any other system, so if this is a NetBSD-specific hack then it needs to go in an .if OPSYS section, and I'd recommend a very good comment explaining why we have both --with and --without because that makes no sense to me.
>> 
>> The problem is, not every operating system provides 'expat_config.h', but pkgsrc thinks the external expat is fine.
> 
> I just tried building after providing an empty expat_config.h, and it
> built fine.

Not on macOS, and other systems with newer expat.

With this patch:


--- Modules/pyexpat.c.orig 2026-03-20 09:03:43.917376558 +0000
+++ Modules/pyexpat.c
@@ -8,7 +8,6 @@
   #include <stdbool.h>
 #include "structmember.h"         // PyMemberDef
-#include "expat_config.h"
 #include "expat.h"
   #include "pyexpat.h"


I get:


/dist/work/lang/python311/work/Python-3.11.15/Modules/pyexpat.c:1227:9: error: use of undeclared identifier
      'XML_SetAllocTrackerActivationThreshold'
 1227 |         XML_SetAllocTrackerActivationThreshold
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
building '_multibytecodec' extension


That's because newer expat.h depends on features defined in expat_config.h. In this particular case XML_SetAllocTrackerActivationThreshold is guarded with "#  if defined(XML_DTD) || (defined(XML_GE) && XML_GE == 1)", and XML_DTD, XML_GE, and XML_GE are defined in expat_config.h.


> So either provide that (manually for this package, or from the
> expat/buildlink3.mk file), or just remove the include from
> Modules/pyexpat.c - I don't see it using anything from that header
> (the '#if's in it only check XML_COMBINED_VERSION, which is not
> provided by that header anyway).

I can commit PREFER.expat=pkgsrc solution, if no objection.

Adam