#[derive(Error)] doesn't work with no-std

[KSXGitHub]

Code

#![no_std]
use derive_more::{Display, Error};

#[derive(Debug, Display, Error)]
#[display(fmt = "This is an error message")]
pub struct MyError;

Repo: https://github.com/KSXGitHub/bug-report-derive-more-error-no-std

Expected behavior

It compiles without error

Actual behavior

error[E0433]: failed to resolve: could not find `std` in the list of imported crates
 --> src/lib.rs:4:26
  |
4 | #[derive(Debug, Display, Error)]
  |                          ^^^^^ could not find `std` in the list of imported crates
  |
  = note: this error originates in the derive macro `Error` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0433`.
error: could not compile `test-derive-error` (lib) due to previous error

[tyranron]

@KSXGitHub yes, because error module is only present in std, to have it in core a nightly feature(error_in_core) is required.

We're not going to support this unless it lands into core on stable Rust.

[JelteF]

To be clear you need to use the current beta release of derive_more together with feature(error_in_core) to have the Error derive working on no_std.

[dependencies]
derive_more = "=1.0.0-beta.3"