Re: python to support SQLite extensions

[Jelle Licht <jlicht@fsfe.org>]

Hey Felix,

Felix Gruber <felgru@posteo.net> writes:

> Hi Jelle,
>
> On 5/10/21 11:31 PM, Jelle Licht wrote:
>> Does anybody perhaps know why my python is correctly receiving (and
>> subsequently ignoring) this configure flag? It seems that *something*
>> happens between the 'configure' script receiving the flag, and the file
>> in `Modules/_sqlite/connection.c' being built, it seems
>> SQLITE_OMIT_LOAD_EXTENSION is set to "1".
>> 
>> This (seemingly) happens in setup.py, lines 1432 and on:
>> --8<---------------cut here---------------start------------->8---
>>  if '--enable-loadable-sqlite-extensions' not in sysconfig.get_config_var("CONFIG_ARGS"):
>>      sqlite_defines.append(("SQLITE_OMIT_LOAD_EXTENSION", "1"))
>> --8<---------------cut here---------------end--------------->8---
>> 
>> Indeed, in *any* python3 I can find on my Guix System, I see:
>> 
>> --8<---------------cut here---------------start------------->8---
>> #> import sysconfig
>> #> sysconfig.get_config_var("CONFIG_ARGS")
>> '--with-system-ffi'
>> --8<---------------cut here---------------end--------------->8---
>> 
>> Something weird is going on!
>> 
>> I have no clue how to continue finding why this happens, but for my
>> personal problem I can just patch python's setup.py file.
>
> You're onto something with `sysconfig.get_config_var("CONFIG_ARGS")`:
> In the definition of the python-2.7 package from which the python
> package eventually derives from, a phase
> `'do-not-record-configure-flags` is added before `'configure`. This
> phase removes everything but '--with-system-ffi' from `CONFIG_ARGS`.
>
> I've successfully enabled loadable sqlite extensions with the following
> package definition.
> -------8<----------------8<----------------8<----------------8<-------
> (define python-with-loadable-sqlite-modules
>   (package (inherit python)
>     (arguments
>      (substitute-keyword-arguments (package-arguments python)
>        ((#:configure-flags cf)
>         `(cons* "--enable-loadable-sqlite-extensions" ,cf))
>        ((#:phases phases)
>         `(modify-phases ,phases
>            (delete 'do-not-record-configure-flags)))))))
> ------->8---------------->8---------------->8---------------->8-------

This works well-enough for me atm, thanks for getting me to understand
the missing part here :).

> While this works, it might be better to modify the
> `'do-not-record-configure-flags` phase to keep the
> `--enable-loadable-sqlite-extensions` option instead of completely
> removing this phase.
>
> I think it might be a good idea to enable loadable sqlite extensions by
> default in the python package. As you've already pointed out, other
> distros have this option enabled which leads to surprises when trying to
> load sqlite extensions in guix's python.

Makes sense, but I am no python guru. I'll open a separate ticket for
this discussion, because there might be more flags that have similar
issues that we might want to support.

Thanks again,
 Jelle