Smart contract deploy error: the feature lang_items is internal to the compiler or standard library

Question

I try to redeploy a MultiversX smart contract for which I haven't changed the code in a while. However, the deploy recently started to fail with this error:

error: the feature `lang_items` is internal to the compiler or standard library                                                      
  --> src/lib.rs:13:12
   |
13 | #![feature(lang_items)]
   |            ^^^^^^^^^^
   |
   = note: using it is strongly discouraged
   = note: `#[deny(internal_features)]` on by default

The issue is that this ![feature...] is in an auto-generated file.

What is causing it?

Answer 1

The issue can be related to the rust version.

For example, rustc 1.73.0 nightly was incompatible with the framework.

Run mxpy deps check rust to see what version you have.

To downgrade the version you can use mxpy deps install rust --tag=nightly-2023-04-24 --overwrite.

A detailed conversation about this problem can be found on here.