Cargo standard library dependencies · Issue #5 · rust-lang/wg-cargo-std-aware (original) (raw)

Provide feedback

This issue is for tracking the writing of an RFC for extending Cargo.toml to specify dependencies on standard library crates.

There are a few needs and requirements:

Opt-in to building the standard library instead of using pre-built artifacts.
Specifying alternate standard library implementations.
Create a way for Cargo to pass --extern=foo to rustc to specify explicit dependencies to add to the extern prelude, even for pre-built artifacts. This can help obviate the need for extern crate for crates like proc-macro.
- We may also consider this to be implicit in some cases. For example, proc-macro could be automatically added with proc-macro = true.

There have been a few different proposals for syntax, please see the following:

Some issues to consider:

How does cargo treat multiple crates in a graph declaring dependencies on the standard library?
How to balance implicit vs explicit dependencies?
How to express a dependency on a pre-built artifact vs building one from source.