bug#52001: numpy CPU dispatch probably prevents builds of python-numpy from being reproducible

[Maxime Devos]

Ricardo Wurmus schreef op za 20-11-2021 om 15:36 [+0000]:
> Numpy accelerates operations with native code.  Early in the build 
> it probes the CPU / compiler for supported instruction extensions 
> and then proceeds to build extensions for different features.  I’m 
> guessing that this won’t work when building on older CPUs, so the 
> results of two builds on different CPUs may differ.
> 
> It would be helpful if someone could confirm this by building 
> numpy on an older CPU and then compare the build result with that 
> provided by ci.guix.gnu.org.
> 

I built it locally, and have the same result as ci.guix.gnu.org.
However, the bordeaux substitute is different:

$ LANGUAGE=en guix challenge python-numpy
/gnu/store/k311v0843hgq5frcbscylwimqssl1h54-python-numpy-1.17.3
contents differ:
  local hash: 07var0wn8fywxchldz5pjqpnlavrlbc8s81aqwsqyi0i7qlh6ka7
 
https://ci.guix.gnu.org/nar/lzip/k311v0843hgq5frcbscylwimqssl1h54-python-numpy-1.17.3
: 07var0wn8fywxchldz5pjqpnlavrlbc8s81aqwsqyi0i7qlh6ka7
 
https://bordeaux.guix.gnu.org/nar/lzip/k311v0843hgq5frcbscylwimqssl1h54-python-numpy-1.17.3
: 0cbl3q19bshb6ddz8xkcrjzkcmillsqii4z852ybzixyp7rg40qa
 bordeaux.guix.gnu.org  3.9MiB                                 6.7MiB/s
00:01 [##################] 100.0%
1 store items were analyzed:
  - 0 (0.0%) were identical
  - 1 (100.0%) differed
  - 0 (0.0%) were inconclusive

Diffoscope output:

 bordeaux.guix.gnu.org  3.9MiB                                 4.2MiB/s 00:01 
[##################] 100.0%
[...]
│ │ │ │ │ │ │ │   --- 
/tmp/guix-directory.6ivbVt/lib/python3.8/site-packages/numpy/distutils/fcompiler/__pycache__/vast.cpython-38.pyc
│ │ │ │ │ │ │ ├── +++ 
/gnu/store/k311v0843hgq5frcbscylwimqssl1h54-python-numpy-1.17.3/lib/python3.8/site-packages/numpy/distutils/fcompiler/__pycache__/vast.cpython-38.pyc
│ │ │ │ │ │ │ │ @@ -106,15 +106,15 @@
│ │ │ │ │ │ │ │  00000690: 0104 0106 0104 0104 0106 0104 f906 0904  
................
│ │ │ │ │ │ │ │  000006a0: 0104 0208 0308 06da 085f 5f6d 6169 6e5f  
.........__main_
│ │ │ │ │ │ │ │  000006b0: 5f29 01da 036c 6f67 e902 0000 0029 01da  
_)...log.....)..
│ │ │ │ │ │ │ │  000006c0: 1463 7573 746f 6d69 7a65 645f 6663 6f6d  
.customized_fcom
│ │ │ │ │ │ │ │  000006d0: 7069 6c65 7272 0700 0000 2901 da08 636f  
pilerr....)...co
│ │ │ │ │ │ │ │  000006e0: 6d70 696c 6572 2911 da0a 5f5f 6675 7475  
mpiler)...__futu
│ │ │ │ │ │ │ │  000006f0: 7265 5f5f 7202 0000 0072 0300 0000 7204  
re__r....r....r.
│ │ │ │ │ │ │ │ -00000700: 0000 0072 1900 0000 da1d 6e75 6d70 792e  
...r......numpy.
│ │ │ │ │ │ │ │ +00000700: 0000 0072 1900 0000 5a1d 6e75 6d70 792e  
...r....Z.numpy.
│ │ │ │ │ │ │ │  00000710: 6469 7374 7574 696c 732e 6663 6f6d 7069  
distutils.fcompi
│ │ │ │ │ │ │ │  00000720: 6c65 722e 676e 7572 0500 0000 da09 636f  
ler.gnur......co
│ │ │ │ │ │ │ │  00000730: 6d70 696c 6572 7372 0600 0000 7227 0000  
mpilersr....r'..
│ │ │ │ │ │ │ │  00000740: 00da 0964 6973 7475 7469 6c73 7233 0000  
...distutilsr3..
│ │ │ │ │ │ │ │  00000750: 00da 0d73 6574 5f76 6572 626f 7369 7479  
...set_verbosity
│ │ │ │ │ │ │ │  00000760: da0f 6e75 6d70 792e 6469 7374 7574 696c  
..numpy.distutil
│ │ │ │ │ │ │ │  00000770: 7372 3500 0000 da05 7072 696e 7472 2000  
sr5.....printr .

1 bit is different.

Greetings,
Maxime.