Allow doc to build with SAGE_PARI_CFG undefined

[kiwifb]

Follow up to #28242 which introduced SAGE_PARI_CFG in documentation build to identity whether or not pari is external.

This is inconvenient to distros and the behavior for external pari should be assumed if SAGE_PARI_CFG is undefined.

Depends on #28242

CC: @dimpase @timokau

Component: distribution

Author: François Bissey

Branch/Commit: 27f17ff

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/28341

[kiwifb]

comment:1

Will replace os.environ['SAGE_PARI_CFG'] by os.environ.get('SAGE_PARI_CFG') in sage_setuo/docbuild/__init__.py.

[kiwifb]

comment:3

@dimpase just so I don't make a mistake. '' is the value you get when pari is coming from the system?

[dimpase]

comment:5

using SAGE_PARI_CFG in docbuild is a hack.
One should really test whether the external pari is multithreaded, this is something that can be done, I just didn't do.

SAGE_PARI_CFG is storing the location of pari.cfg, something hard to find out, and needed to install gp2c, see https://github.com/sagemath/sagetrac-mirror/blob/46772dbb31f2be940bda299136455f495c6a21dc/build/pkgs/gp2c/spkg-configure.m4

[kiwifb]

comment:6

Replying to @dimpase:

using SAGE_PARI_CFG in docbuild is a hack.
One should really test whether the external pari is multithreaded, this is something that can be done, I just didn't do.

SAGE_PARI_CFG is storing the location of pari.cfg, something hard to find out, and needed to install gp2c, see https://github.com/sagemath/sagetrac-mirror/blob/46772dbb31f2be940bda299136455f495c6a21dc/build/pkgs/gp2c/spkg-configure.m4

Yes, I figured that out. On the other hand sage_setup/docbuild/__init__.py may not be the right place to check. So at the moment I just want to make sure that on distro where you don't run configure you get the same result as what you would expect if sage doesn't build pari but finds it on the system.

[dimpase]

comment:7

Replying to @kiwifb:

@dimpase just so I don't make a mistake. '' is the value you get when pari is coming from the system?

This is the value I set. But you can just unconditionally switch to the appropriate docbuilder in Gentoo.

[kiwifb]

comment:8

Replying to @dimpase:

Replying to @kiwifb:

@dimpase just so I don't make a mistake. '' is the value you get when pari is coming from the system?

This is the value I set. But you can just unconditionally switch to the appropriate docbuilder in Gentoo.

I remarked on that in #28242. This is about having something working out of the box without extra patching or settings. Just using os.environ.get() already does enable me to build the doc without SAGE_PARI_CFG being set, which is a progress. I am testing the alternative builder now. Not that I can currently build the doc on Volker's branch because there is a label missing in the doc for manifolds from one of the tickets he is trying to merge.

[kiwifb]

Last 10 new commits:

b622942	spkg-configure for pari_elldata
2e11aed	spkg-configure's for PARI packages
183f47c	check for PARI packages in PARI's spkg-configure
72f3c20	spkg-configure for gp2c
6eac550	as pari might become dummy, test with GAP
ac207d5	don't export GP_DATA_DIR, remove other, unneeded GP* vars
317f090	proper dependency resolution (all tests in PARI spkg-config)
2c26115	docbuild workaround for external PARI
dd2b3fa	redirect gp errors to config.log
27f17ff	Add appropriate fallback if SAGE_PARI_CFG is missing

[kiwifb]

Commit: 27f17ff

[kiwifb]

Author: François Bissey

[kiwifb]

Dependencies: 28242

[kiwifb]

Branch: u/fbissey/pari_cfg_doc

[dimpase]

Changed dependencies from 28242 to #28242

[dimpase]

Reviewer: Dima Pasechnik

[dimpase]

comment:11

lgtm

[vbraun]

Changed branch from u/fbissey/pari_cfg_doc to 27f17ff