Migrate from lazy_static to once_cell

[jaudiger]

lazy_static!, while a declarative macro, is a macro nonetheless. It can add quite a bit of additional compilation time cost. once_cell::sync::Lazy does the same thing with generics, and can be used more flexibly (i.e. non-static lazily initialized values), and has been proposed to be added to std: rust-lang/rfcs#2788.

Famous Rust projects already did the transition, such as:

• Replace lazy_static with once_cell tokio-rs/tokio#3187
• Migrate from lazy_static to once_cell tokio-rs/tracing#2147

[lucab]

Thanks for the report. Sounds like a good idea! I'll be happy to review a patch doing this if anybody wants to tackle it.

[jaudiger]

Hi @lucab, thanks, I just opened a PR for it !