Attribute Macro flipper0::main

#[main]

Transforms input fn to conforms fap entry-point signature, for example look at entry-point of any official app such as that. Only signature transforms, but not a body.

What exactly does this macro do:

1. Read function definition and fix it to satisfy Flipper requirements.

pub unsafe extern "C" fn init(_: *mut u8) -> i32 { 0 }

Then if export-fam feature is enabled:

1. Read existing previously generated manifest (fam) or try to create new one,
2. Write passed function name as entry_point to the manifest.