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Make <*const/mut T>::offset_from const fn

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This commit is contained in:
Oliver Scherer 2019-08-20 17:51:54 +02:00
parent e0436d912d
commit 88b5e945e0
10 changed files with 276 additions and 3 deletions
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18
src/libcore/ptr/mod.rs
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@ -1286,7 +1286,22 @@ impl<T: ?Sized> *const T {
/// }
/// ```
#[unstable(feature = "ptr_offset_from", issue = "41079")]
#[cfg(not(bootstrap))]
#[rustc_const_unstable(feature = "const_ptr_offset_from")]
#[inline]
pub const unsafe fn offset_from(self, origin: *const T) -> isize where T: Sized {
let pointee_size = mem::size_of::<T>();
let ok = 0 < pointee_size && pointee_size <= isize::max_value() as usize;
// assert that the pointee size is valid in a const eval compatible way
// FIXME: do this with a real assert at some point
[()][(!ok) as usize];
intrinsics::ptr_offset_from(self, origin)
}
#[unstable(feature = "ptr_offset_from", issue = "41079")]
#[inline]
#[cfg(bootstrap)]
/// bootstrap
pub unsafe fn offset_from(self, origin: *const T) -> isize where T: Sized {
let pointee_size = mem::size_of::<T>();
assert!(0 < pointee_size && pointee_size <= isize::max_value() as usize);
@ -2013,8 +2028,9 @@ impl<T: ?Sized> *mut T {
/// }
/// ```
#[unstable(feature = "ptr_offset_from", issue = "41079")]
#[rustc_const_unstable(feature = "const_ptr_offset_from")]
#[inline]
pub unsafe fn offset_from(self, origin: *const T) -> isize where T: Sized {
pub const unsafe fn offset_from(self, origin: *const T) -> isize where T: Sized {
(self as *const T).offset_from(origin)
}