networkx-3.2.1_1: /usr/lib/python3.12/site-packages/networkx/readwrite/tests/test_gml.py:557: SyntaxWarning: invalid octal escape sequence '\420'

[datenwolf]

Installing through distribution package manager, at the "Byte-compiling python3.12 code for module networkx..." stage, the following errors are reported:

python3-networkx-3.2.1_1: configuring ...
Byte-compiling python3.12 code for module networkx...
usr/lib/python3.12/site-packages/networkx/readwrite/tests/test_gml.py:557: SyntaxWarning: invalid octal escape sequence '\420'
  "graph [edge [ source u'u\4200' target u'u\4200' ] "
usr/lib/python3.12/site-packages/networkx/readwrite/tests/test_gml.py:558: SyntaxWarning: invalid octal escape sequence '\420'
  + "node [ id u'u\4200' label b ] ]"
usr/lib/python3.12/site-packages/networkx/readwrite/tests/test_gml.py:557: SyntaxWarning: invalid octal escape sequence '\420'
  "graph [edge [ source u'u\4200' target u'u\4200' ] "
usr/lib/python3.12/site-packages/networkx/readwrite/tests/test_gml.py:558: SyntaxWarning: invalid octal escape sequence '\420'
  + "node [ id u'u\4200' label b ] ]"

[MridulS]

Hmm, which package manager is this? We only package pypi and conda-forge.

[datenwolf]

It's installed through my Linux distribution's package manager as some other package's sub-dependency. But that doesn't matter, because the issue can be easily found here

networkx/networkx/readwrite/tests/test_gml.py

Line 557 in 9cc8b42

"graph [edge [ source u'u\4200' target u'u\4200' ] "

Don't shoot the messenger! Paste that string into the Python REPL:

Python 3.12.0 (main, Oct  6 2023, 16:16:58) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print( "graph [edge [ source u'u\4200' target u'u\4200' ] " )
<stdin>:1: SyntaxWarning: invalid octal escape sequence '\420'

The code is broken, namely some escape sequences written incorrectly.

[MridulS]

Yeah thanks for the report!
It's just weird our tests (or us) didn't catch this, we had similar issues #7064, #7032 before which were fixed.

Which linux distribution is this? How did you arrive at this step? (just trying to debug this)

[datenwolf]

It's Voidlinux. Their basic philosophy is, to take upstream as is with zero custom patches. On my system networkx is pulled in as a dependency of python3-scikit-image

[dschult]

Interesting that the syntax warning says the octal sequence is \420 when the actual string says \4200

[rossbar]

It's just weird our tests (or us) didn't catch this

FWIW I have noticed this warning when I run tests locally, I just hadn't gotten around to fixing it yet. We should double-check to see if we have at least one job in CI (preferably on latest Python) that converters all warnings to errors (at least the ones that are not explicitly caught).

Interesting that the syntax warning says the octal sequence is \420 when the actual string says \4200

I assume the test was going for the unicode 4200 character, but it's hard to know for sure. The potential solution that I went with in #7159 was to turn the \ into a literal escape (\\) so that it's interpreted as \ in the string. Another possible solution would be to replace the whole u\4200 with the actual unicode character. I'm not 100% sure what specifically this was designed to test, so opinions welcome!

[datenwolf]

Uhhh, aren't Unicode escape sequences supposed to put the u after the backslash? Like print('\u4200') → 䈀? Am I missing something here?

[rossbar]

Am I missing something here?

Yeah, I think we all are :). My hypothesis that this was intended to be a unicode character (that was written incorrectly) was really just a guess based on context.