Method shrink

aiscript-arena/src/allocator_api.rs:116–128

(
        &self,
        ptr: NonNull<u8>,
        old_layout: Layout,
        new_layout: Layout,
    )

    #[inline]
    unsafe fn shrink(
        &self,
        ptr: NonNull<u8>,
        old_layout: Layout,
        new_layout: Layout,
    ) -> Result<NonNull<[u8]>, AllocError> {
        unsafe {
            let ptr = self.allocator.shrink(ptr, old_layout, new_layout)?;
            self.metrics
                .mark_external_deallocation(old_layout.size() - new_layout.size());
            Ok(ptr)
        }
    }
}

unsafe impl<A: 'static> Collect for MetricsAlloc<'_, A> {