CODEWITHSUNDEEP
macrosrustdependency-managementrust-cargo
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Reputation: 6447

How can I get similar dependency resolution to Cargo in an existing project with only rustc for code analysis?

The Rust book mentions that macros can be expanded with the command rustc --pretty expanded. I'd like to use this for testing some macros I wrote in a crate, by expanding an example file with a command like

rustc -Z unstable-options --pretty expanded examples/macro_test.rs

macro_test.rs would have code that looks like this:

#[macro_use] extern crate macro_crate;

use macro_crate::macros::*;

macro_foo! { foo }

fn main() {}

However, that results in error 0463, which is that rustc doesn't know anything about the crate environment it's in:

error[E0463]: can't find crate for `macro_crate`
 --> examples/macro_test.rs:1:1
  |
1 | extern crate macro_test;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

What's the recommended way to work with this? The cargo help doesn't have anything directly related as far as I can tell.

Upvotes: 1

Views: 110

Answers (1)

Francis Gagné
Francis Gagné

Reputation: 65782

Cargo has a rustc subcommand for invoking rustc with additional arguments.

$ cargo rustc --example macro_test -- -Z unstable-options --pretty expanded

You can also add --verbose before the -- to get Cargo to print the full rustc command line (among other things).

Upvotes: 3

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