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implement ptr::write without dedicated intrinsic
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@ -768,13 +768,6 @@ extern "rust-intrinsic" {
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#[rustc_const_stable(feature = "const_size_of", since = "1.40.0")]
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pub fn size_of<T>() -> usize;
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/// Moves a value to an uninitialized memory location.
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///
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/// Drop glue is not run on the destination.
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///
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/// The stabilized version of this intrinsic is [`core::ptr::write`](crate::ptr::write).
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pub fn move_val_init<T>(dst: *mut T, src: T);
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/// The minimum alignment of a type.
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///
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/// The stabilized version of this intrinsic is [`core::mem::align_of`](crate::mem::align_of).
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@ -883,12 +883,18 @@ pub const unsafe fn read_unaligned<T>(src: *const T) -> T {
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub unsafe fn write<T>(dst: *mut T, src: T) {
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if cfg!(debug_assertions) && !is_aligned_and_not_null(dst) {
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// Not panicking to keep codegen impact smaller.
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abort();
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// We are calling the intrinsics directly to avoid function calls in the generated code.
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extern "rust-intrinsic" {
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fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
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}
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// SAFETY: the caller must guarantee that `dst` is valid for writes.
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// `dst` cannot overlap `src` because the caller has mutable access
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// to `dst` while `src` is owned by this function.
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unsafe {
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copy_nonoverlapping(&src as *const T, dst, 1);
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intrinsics::forget(src);
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}
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// SAFETY: the caller must uphold the safety contract for `move_val_init`.
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unsafe { intrinsics::move_val_init(&mut *dst, src) }
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}
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/// Overwrites a memory location with the given value without reading or
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