[−][src]Crate cargo_emit

Talk to Cargo easily at build time, brought to you by Nikolai Vazquez.

This library provides:

Convenience macros for communicating with Cargo during the build.rs phrase. Cargo listens to certain build script outputs that dictate how it should behave.
An accessible location for seeing what script build outputs are available to emit.
Protection against typos that can be made when printing these formatted outputs directly yourself. Mistyping macro names will result in a compile failure.

Usage

This crate is available on crates.io and can be used by adding the following to your project's Cargo.toml:

[build-dependencies]
cargo-emit = "0.1"

and something like this to your build.rs:

if should_warn {
    cargo_emit::warning!("(C-3PO voice) We're doomed");
}

Note: This library is meant to be used with Rust 2018 edition, so that cargo_emit:: can be used to prefix macro calls.

Compatibility

This crate is compatible with Rust 1.31+ in order to use the $crate::macro! feature introduced in Rust 2018.

Examples

Very thorough examples are provided in the docs for each individual macro.

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Macros

pair	Emits a `$key`/`$value` pair to Cargo based on build script outputs.
rerun_if_changed	Tells Cargo to run again if the file or directory at `$path` changes.
rerun_if_env_changed	Tells Cargo to run again if the file or directory at `$var` changes.
rustc_cdylib_link_arg	Tells Cargo to pass `-C link-arg=$flag` to the compiler.
rustc_cfg	Tells Cargo to enable a `$feature`.
rustc_env	Tells Cargo to assign `$var` for the environment variable for `$key`.
rustc_flags	Tells Cargo to pass `$flags` to the compiler.
rustc_link_lib	Tells Cargo to pass `$lib` to the compiler as a `-l` flag.
rustc_link_search	Tells Cargo to pass `$path` to the compiler as a `-L` flag.
warning	Tells Cargo to print the formatted `warning` message.