rust/tests/ui/packed/packed-struct-generic-layout.rs

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// run-pass
#![allow(dead_code)]
#![allow(overflowing_literals)]
core: Remove the cast module This commit revisits the `cast` module in libcore and libstd, and scrutinizes all functions inside of it. The result was to remove the `cast` module entirely, folding all functionality into the `mem` module. Specifically, this is the fate of each function in the `cast` module. * transmute - This function was moved to `mem`, but it is now marked as #[unstable]. This is due to planned changes to the `transmute` function and how it can be invoked (see the #[unstable] comment). For more information, see RFC 5 and #12898 * transmute_copy - This function was moved to `mem`, with clarification that is is not an error to invoke it with T/U that are different sizes, but rather that it is strongly discouraged. This function is now #[stable] * forget - This function was moved to `mem` and marked #[stable] * bump_box_refcount - This function was removed due to the deprecation of managed boxes as well as its questionable utility. * transmute_mut - This function was previously deprecated, and removed as part of this commit. * transmute_mut_unsafe - This function doesn't serve much of a purpose when it can be achieved with an `as` in safe code, so it was removed. * transmute_lifetime - This function was removed because it is likely a strong indication that code is incorrect in the first place. * transmute_mut_lifetime - This function was removed for the same reasons as `transmute_lifetime` * copy_lifetime - This function was moved to `mem`, but it is marked `#[unstable]` now due to the likelihood of being removed in the future if it is found to not be very useful. * copy_mut_lifetime - This function was also moved to `mem`, but had the same treatment as `copy_lifetime`. * copy_lifetime_vec - This function was removed because it is not used today, and its existence is not necessary with DST (copy_lifetime will suffice). In summary, the cast module was stripped down to these functions, and then the functions were moved to the `mem` module. transmute - #[unstable] transmute_copy - #[stable] forget - #[stable] copy_lifetime - #[unstable] copy_mut_lifetime - #[unstable] [breaking-change]
2014-05-09 17:34:51 +00:00
use std::mem;
#[repr(packed)]
struct S<T, S> {
a: T,
b: u8,
c: S
}
pub fn main() {
unsafe {
let s = S { a: 0xff_ff_ff_ffu32, b: 1, c: 0xaa_aa_aa_aa as i32 };
let transd : [u8; 9] = mem::transmute(s);
// Don't worry about endianness, the numbers are palindromic.
assert_eq!(transd,
[0xff, 0xff, 0xff, 0xff,
1,
0xaa, 0xaa, 0xaa, 0xaa]);
let s = S { a: 1u8, b: 2u8, c: 0b10000001_10000001 as i16};
let transd : [u8; 4] = mem::transmute(s);
// Again, no endianness problems.
assert_eq!(transd,
[1, 2, 0b10000001, 0b10000001]);
}
}