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Maybe Waffle 2021-10-29 23:45:09 +03:00
parent 878ac10fe1
commit afaa54a99d
1 changed files with 9 additions and 8 deletions
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17
library/core/src/slice/raw.rs
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@ -141,17 +141,18 @@ const fn debug_check_data_len<T>(data: *const T, len: usize) {
assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
}
const fn ctfe_check<T>(_data: *const T) {
// It's impossible to check alignment in const fn.
//
// CTFE engine checks that the pointer is aligned and not null.
}
const fn noop<T>(_: *const T) {}
// SAFETY:
// - `calling from_raw_parts[_mut]` with arguments that fail to fulfil checks made here is UB, so unless UB is already triggered this is noop
// - CTFE makes the same checks as `rt_check`, so behavior change is not observable due to compilation error
//
// `rt_check` is just a debug assert to hint users that they are causing UB,
// it is not required for safety (the safety must be guatanteed by
// the `from_raw_parts[_mut]` caller).
//
// Since the checks are not required, we ignore them in CTFE as they can't
// be done there (alignment does not make much sense there).
unsafe {
crate::intrinsics::const_eval_select((data,), ctfe_check, rt_check);
crate::intrinsics::const_eval_select((data,), noop, rt_check);
}
assert!(