2018-08-30 12:18:55 +00:00
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//@ run-pass
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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
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use std::mem;
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2013-05-25 02:35:29 +00:00
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2014-05-27 06:56:52 +00:00
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#[repr(packed)]
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2023-12-27 22:11:58 +00:00
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#[allow(dead_code)]
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2014-12-20 02:20:51 +00:00
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struct S4(u8,[u8; 3]);
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2013-04-10 13:47:53 +00:00
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2014-05-27 06:56:52 +00:00
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#[repr(packed)]
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2023-12-27 22:11:58 +00:00
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#[allow(dead_code)]
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2013-04-10 13:47:53 +00:00
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struct S5(u8,u32);
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2013-09-25 07:43:37 +00:00
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pub fn main() {
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2013-04-10 13:47:53 +00:00
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unsafe {
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let s4 = S4(1, [2,3,4]);
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2014-12-20 02:20:51 +00:00
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let transd : [u8; 4] = mem::transmute(s4);
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2015-06-07 18:00:38 +00:00
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assert_eq!(transd, [1, 2, 3, 4]);
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2013-04-10 13:47:53 +00:00
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let s5 = S5(1, 0xff_00_00_ff);
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2014-12-20 02:20:51 +00:00
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let transd : [u8; 5] = mem::transmute(s5);
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2013-04-10 13:47:53 +00:00
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// Don't worry about endianness, the u32 is palindromic.
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2015-06-07 18:00:38 +00:00
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assert_eq!(transd, [1, 0xff, 0, 0, 0xff]);
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2013-04-10 13:47:53 +00:00
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}
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}
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