Compile with stable Rust

[frol]

Currently, nearcore can only be compiled with nightly Rust compiler due to the following unstable features:

• wasmer-singlepass-backend requires proc_macro_hygiene*

  * It seems that Rust 1.44 can have the necessary parts of it stabilized! Stabilize fn-like proc macros in expression, pattern and statement positions rust-lang/rust#68717

• dynasm [dependency of wasmer-singlepass-backend] requires - 0.7.0 release is going to be compilable on stable Rust 1.45:

  • proc_macro_diagnostic (can be easily conditionaly disabled on stable)
  • proc_macro_span (it seems that it can be mocked on stable)

It seems that we can have nearcore compiled on stable Rust once proc_macro_hygiene is stabilized (mid June?) and dynasm has unstable features under feature flags.

/cc @nearmax @bowenwang1996

[frol]

dynasm-rs 0.7 release should be compilable on stable Rust 1.45 release (the release is scheduled for July 16th), so it seems that it is only a matter of wasmer singlepass backend to upgrade to dynasm-rs 0.7 release (wasmerio/wasmer#1488).

/cc @nearmax @olonho

[olonho]

Great to know!

[frol]

dynasm-rs has its 1.0 release (they decided to have this milestone of compilation on stable Rust 1.45+ clearly communicated).

wasmer needs to migrate to this new version and they claim that the support is already addressed in their new refactored version of wasmer:

We are working on the new version of Wasmer that will be released to the public soon.

In this new version we are already using the latest version of Cranelift (that also supports Aarch64), and have passed all tests successfully in our ARM servers.

So we just have to wait for a few weeks to see the support upstream! :)