std::macros::builtin::env![src]
macro_rules! env( ($name:expr) => ({ /* compiler built-in */ }) )
Inspect an environment variable at compile time.
This macro will expand to the value of the named environment variable at
compile time, yielding an expression of type &'static str.
If the environment variable is not defined, then a compilation error
will be emitted. To not emit a compile error, use the option_env!
macro instead.
Example
fn main() { let home: &'static str = env!("HOME"); println!("the home directory at the time of compiling was: {}", home); }let home: &'static str = env!("HOME"); println!("the home directory at the time of compiling was: {}", home);