Function Subspace :: sus :: ptr :: copy

template <class T>
auto copy(UnsafeFnMarker, const T* src, T* dst, usize count) -> void

Copies count * size_of<T>() bytes from src to dst. The source and destination may overlap.

If the source and destination will never overlap, copy_nonoverlapping can be used instead.

copy is semantically equivalent to memmove, but with the argument order swapped. Copying takes place as if the bytes were copied from src to a temporary array and then copied from the array to dst.

The copy is “untyped” in the sense that data may be uninitialized or otherwise violate the requirements of T. The initialization state is preserved exactly.


This function will panic if the number of bytes, count * size_of<T>(), overflows.


Behavior is undefined if any of the following conditions are violated:

  • src must be valid for reads of count * size_of<T>() bytes.
  • dst must be valid for writes of count * size_of<T>() bytes.
  • dst must not have an overlapping object in its tail padding. If dst is in an array, or was heap allocated, then this will always be satisfied.

copy creates a bitwise copy of T, regardless of whether T is TrivialCopy or TriviallyRelocatable. If T is not TrivialCopy, using the value in *dst can violate memory safety. If T is not TriviallyRelocatable, using both the values in *src and in *dst can violate memory safety.

Note that even if the effectively copied size (count * size_of<T>()) is 0, the pointers must be non-null and properly aligned.