Deprecate the `-R` option

[StanFromIreland]

Feature or enhancement

Proposal:

The documentation can be found here. Note that it is not documented in the --help text since randomization became default in 3.3 (c9f54cf5).

This option generally does nothing [except for a special case described below]. As randomization is enabled by default since 3.3 (c9f54cf5). Currently, the option only has an effect in the case when PYTHONHASHSEED is set to a specific seed, overriding it. This is even wrongly documented (see #137608). This exception also did not work till 3.7 (358e5e17), so there were 4 versions where in all cases, the option was a NO-OP. Seeing as no user (Apart from Victor) noticed, it can be reasonably concluded that this option is not widely used.

I propose to deprecate the option for the standard period of two versions, and then convert it to a NO-OP for backwards-compatibility like the -t option.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

The proposal on Discourse received no objections.

Linked PRs

• gh-137897: Deprecate the -R option #137898

[vstinner]

it can be reasonably concluded that this option is not widely used

Ok, but I'm not convinced that it's worth it to change it. The code and the doc are already written, it requires minimum maintenance. The option remains useful to override an env var (PYTHONHASHSEED).