macro_rules! rustc_env { ($($tokens:tt)*) => { ... }; }
Expand description
The rustc_env instruction tells Cargo to set the given environment
variable when compiling the package. The value can be then retrieved by the
env! macro in the compiled crate. This is useful for embedding additional
metadata in crate’s code, such as the hash of git HEAD or the unique
identifier of a continuous integration server.
See also the environment variables automatically included by Cargo.
For more information, see this cargo reference.