Deprecation warnings from pyparsing library

[jennifer-richards]

Describe the bug
As of v3.3.0 (Dec 2025), the pyparsing library has begun emitting DeprecationWarnings for use of non-PEP8-compliant method aliases. These are triggered by bibtexparser.

Reproducing

Version: 1.4.3

Code:

import warnings
warnings.simplefilter("always", DeprecationWarning)
import bibtexparser
bibtexparser.bparser.BibTexParser()

Bibtex:
No bibtex required

Workaround
Suppress DeprecationWarnings from the bibtexparser and pyparsing modules. Brute force approach not tailored to the specific warnings:

warnings.filterwarnings("ignore", category=DeprecationWarning, module="bibtexparser")
warnings.filterwarnings("ignore", category=DeprecationWarning, module="pyparsing")

Remaining Questions (Optional)
Please tick all that apply:

• I would be willing to contribute a PR to fix this issue.
• This issue is a blocker, I'd be grateful for an early fix.

[MiWeiss]

Hi @jennifer-richards .

Thanks for offering to contribute a PR. I am looking forward to reviewing it.

Attention: This issue refers to bibtexparser v1 (which lives on a separate branch, not the main branch - check the README)

[jennifer-richards]

Question for the pr: is nudging the pyparsing dependency up to 3.0 from its current 2.0 (or so) acceptable, or is it necessary to maintain support for the older library? The now-deprecated aliases were added in 3.0, so it'll be a more complex patch to support both.

[MiWeiss]

Yep, I don't see any problem there. Current constaint sais 'pyparsing>=2.0.3', so most users will be on 3.x anyways, and compatibility should also be given.

[KevinODonovan60]

ietf-tools/datatracker#10140