use std::lazy::SyncLazy instead of lazy_static

[light4]

Can we use the nightly feature once_cell?

[ytmimi]

Thanks for your first PR!

Can we use the nightly feature once_cell?

Speaking for myself, I don't see why we couldn't use it. I'm personally not too familiar with the once_cell feature. It would be great if you could elaborate on the advantages to using this over lazy_static!. Is the idea just to replace a 3rd party dependency?

[light4]

1. Remove a 3rd party dependency
2. Macro free
3. When the feature is stabled, we can just switch over it
4. Performance improvement according to this use once_cell instead of lazy_static async-rs/async-std#406

This is the once_cell tracing issue: rust-lang/rust#74465

[ytmimi]

That all sounds awesome! Thanks for including those links. I'll be sure to give them a read 😄

[calebcartwright]

Thanks for the PR!

We've historically stayed away from any gated features (obviously excluding rustc_private which we need for consuming compiler internals). However, while I'm not sure I'm ready to take the plunge into using unstable features I also think we're kidding ourselves if we continue that refrain based on hopes of being able to build with a stable compiler some day.

That being said, I'm still on the fence about this one as I don't think it buys us all that much just yet, given that lazy_static is still in our build graph due to various transitive dependencies and we'd technically be pulling in once_cell too.

I concur that this is the right move strategically, but not quite convinced yet that it's all that beneficial today. Will leave it parked for a bit in case I change my mind.

[ytmimi]

This one is still on hold, but I wanted to mention that the latest tracking issue for this is rust-lang/rust#109736.