Macro mac::if_cfg
[−]
[src]
macro_rules! if_cfg { ($cfg:meta $t:block else $f:block) => { ... }; ($cfg:meta $t:block) => { ... }; }
Compile-time conditional expression.
Example
if_cfg!(test { println!("Crate built as a test suite"); })
Unlike if cfg!(...)
, this will not even compile the unused branch.
let x = if_cfg!(any(bleh, blah="bluh") { some_undefined_function_name(); 2 + "doesn't even typecheck" } else { 3 }); assert_eq!(x, 3);