make serde safe

[bkontur]

Hi guys,

please, I just want to ask, could serde-rs/serde#2096 be relevant from your point if view?
is it something, which could be easily fixed? or does it make even sense?
Thank you for any response :)

[Shnatsel]

I have looked into this in the past, and it appears to be both correct and necessary for performance. It does make sense in that particular situation.

Writing to the buffer could potentially be gated on some sort of newtype which would only allow writing valid ASCII, but I'm not sure if it's worth it in this case (and would increase the unsafe count by the metrics, but metrics are imperfect)