Function alloc::heap::reallocate_inplace

pub unsafe fn reallocate_inplace(ptr: *mut u8, old_size: usize, size: usize, align: usize) -> usize

Unstable (heap_api #27700)

: the precise API and guarantees it provides may be tweaked slightly, especially to possibly take into account the types being stored to make room for a future tracing garbage collector

Resize the allocation referenced by ptr to size bytes.

If the operation succeeds, it returns usable_size(size, align) and if it fails (or is a no-op) it returns usable_size(old_size, align).

Behavior is undefined if the requested size is 0 or the alignment is not a power of 2. The alignment must be no larger than the largest supported page size on the platform.

The old_size and align parameters are the parameters that were used to create the allocation referenced by ptr. The old_size parameter may be any value in range_inclusive(requested_size, usable_size).