Should there be a Once::try_call_once

[nbdd0121]

I wonder if Once should have a try_call_once method for failable initialization, which accepts a FnOnce() -> Result<(), E>.

OnceCell has a get_or_try_init method which can fail, so I think it would make sense for Once to have a failable initialisation method as well. Note that due to lack of failable init in Once right now, OnceCell currently need to rely on pub(crate) method to posion the Once for get_or_try_init.

cc #33577

@rustbot modify labels: +T-libs

[MarinPostma]

I think this would be very useful for fallible, per-process initialization. How can we push this forward?

[ChrisDenton]

Nowadays the best way is to create an ACP. This ensures a new API proposal will be considered by the libs-api team.