Does `extern crate` serve any purpose in the 2021 edition?

help
1

Are there any situations where extern crate needs to be used in the 2021 (or 2018) edition, or is it there purely for backwards compatibility?

2 Likes
2

See:

(click here to see full thread)

2 Likes
3

extern crate is still useful if you want to import all macros from a crate like

#[macro_use] // to bring `anyhow!`, `bail!` and `ensure!` into scope
extern crate Anyhow;
1 Like
4

I would not recommend that. It's much less clear than use, and an artifact of old system.

2 Likes
5

As in the other thread, extern crate alloc; is one use, as is #![no_std] #[cfg(feature = "std")] extern crate std;.

One use that I don't see often mentioned is extern crate self as name, which allows you to use ::name in addition to ::crate to refer to your own crate. This can be useful for e.g. macros, or even just for making internal code look more like external code.

9 Likes
6

This topic was automatically closed 90 days after the last reply. We invite you to open a new topic if you have further questions or comments.