Non-standard characters in field names can lead to error when initializing a model using double star and a dictionary

[luizfelippesr]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

When some special characters are used as field names, initializing a model using a dictionary leads to a validation error.

Example Code

import pydantic

class Example(pydantic.BaseModel):
    width_µm: float

my_data = {'width_µm': 33}

# The following works fine
this_works = Example(width_µm = 42)

# However, this does not work
this_does_not_work = Example(**my_data)

Python, Pydantic & OS Version

pydantic version: 2.7.1
        pydantic-core version: 2.18.2
          pydantic-core build: profile=release pgo=false
                 install path: /home/lfsr/miniforge3/envs/ds/lib/python3.12/site-packages/pydantic
               python version: 3.12.2 | packaged by conda-forge | (main, Feb 16 2024, 20:50:58) [GCC 12.3.0]
                     platform: Linux-6.5.0-28-generic-x86_64-with-glibc2.38
             related packages: typing_extensions-4.10.0
                       commit: unknown

[sydney-runkle]

@luizfelippesr,

Thanks for reporting. I can indeed confirm that this is an issue. PRs welcome with a fix, though I don't think this is high priority.