start
The tracking issue for this feature is: #29633
Allows you to mark a function as the entry point of the executable, which is
necessary in #![no_std]
environments.
The function marked #[start]
is passed the command line parameters in the same
format as the C main function (aside from the integer types being used).
It has to be non-generic and have the following signature:
This feature should not be confused with the start
lang item which is
defined by the std
crate and is written #[lang = "start"]
.
Usage together with the std
crate
#[start]
can be used in combination with the std
crate, in which case the
normal main
function (which would get called from the std
crate) won't be
used as an entry point.
The initialization code in std
will be skipped this way.
Example:
Unwinding the stack past the #[start]
function is currently considered
Undefined Behavior (for any unwinding implementation):
#![feature(start)]
#[start]
fn start(_argc: isize, _argv: *const *const u8) -> isize {
std::panic::catch_unwind(|| {
panic!(); // panic safely gets caught or safely aborts execution
});
panic!(); // UB!
0
}