TL;DR: After noticing an annoying warning, I went on an absurd yak shave, and discovered that because of a tiny handful of Python packages built with an appealing-sounding but dangerous compiler option, more than 2,500 Python packages—some with more than a million downloads per month—could end up causing any program that uses them to compute incorrect numerical results. Once Upon a Time in My Terminal Recently, whenever I tried to import certain Python packages (notably, some models from Huggingface Transformers), I would see this weird and unsightly warning: Python 3.8.10 (default, Jun 22 2022, 20:18:18) Type 'copyright', 'credits' or 'license' for more information IPython 8.4.0 -- An enhanced Interactive Python. Type '?' for help. In [ 1 ]: from transformers import CodeGenForCausalLM /home/moyix/.virtualenvs/sfcodegen/lib/python3.8/site-packages/numpy/core/getlimits.py:498: UserWarning: The value of the smallest subnormal for <class 'numpy.