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Stable vs. Nightly Rust

Required Rust version​

Starting with framework version v0.50.0, MultiversX smart contracts can be built using stable Rust.

Before this version, nightly Rust was required.

For everything after v0.50.0 we recommend running the latest stable version of Rust. Older versions have had compatibility issues with certain framework dependencies, on certain versions of the compiler.

Nightly Rust is still allowed, but not recommended. We will still be supporting nightly builds and running continuous integration on nightly-2024-05-22.

Also, everything on versions older than v0.50.0 needs to run on nightly Rust.

So, to summarize:

  • Before v0.50: nightly-2023-12-11 and nightly-2024-05-22 are both known to be running fine;
  • On v0.50 (use v0.50.6): any version of stable Rust;
  • Starting with v0.51: stable, Rust >= 1.78 required.

Why Nighly for the older versions?​

There were several nightly features that the framework was using, which we had hoped to see stabilized sooner.

These are of little relevance to the average developer, but for the record, let's mention a few of them and how we managed to circumvent their usage:

  • never_type - avoided by using slightly different syntax;
  • auto_traits and negative_impls - avoided by redesigning the CodecFrom/TypeAbiFrom trait systems;
  • generic_const_exprs - replaced with massive amounts of macros;
  • panic_info_message - replaced by a different method to retrieve the panic message.

If any of these get stabilized in the future, we might revert the changes enacted in v0.50.0.

It is in any case our commitment to keep the framework compatible with stable Rust from here on, no matter what.