Symfony version(s) affected

all

Description

When looking at Symfony standard about template naming
(https://symfony.com/doc/current/templates.html#template-naming or https://symfony.com/doc/current/best_practices.html#use-snake-case-for-template-names-and-variables)
it's said:

Use snake case for filenames and directories (e.g. blog_posts.html.twig, admin/default_theme/blog/index.html.twig, etc.);

Now, If we look at the UnicodeString::snake() in order to knows what a valid snake case is:
https://github.com/symfony/string/blob/7.0/Tests/AbstractAsciiTestCase.php#L1063-L1077
it seems that foo_2 is not a valid snake case and should be foo2.

But, when looking at symfony code
https://github.com/symfony/symfony/tree/7.1/src/Symfony/Bridge/Twig/Resources/views/Form
all the templates with number are in the format foo_2 instead of foo2
and therefore are not respecting the own Symfony templates naming standard.

How to reproduce

Irrelevant

Possible Solution

I see four solutions:

1. Updating the naming standard to explain the "snake_case" strategy prefix all numbers a with an underscore
   => Certainly the simplest but less satisfying solution because it kinda introduce a new naming strategy witch is not even supported by Symfony/string.

2. Changing the snake method strategy
   => Seems this is a BC break, this seem impossible

3. Allow passing a new parameters to snake method/introduce a new method related to this snake_case_numeric strategy
   => Since [String] Introduce underscore() method #34781 was closed, not sure it will be preferred now (@simPod & @nicolas-grekas)

4. Renaming the templates with numbers in a BC way.
   => Might be the best solution, it just need a little work to avoid BC break.

Additional Context

No response