raw_parts

Peeling back safe abstractions on heap data.

# // Copyright 2025 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
impl<T> Vec<T> {
    // Note how this is an unsafe function
    unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T>;

    fn into_raw_parts(self) -> (*mut T, usize, usize);
}

• raw_parts denotes methods that construct items from or decompose items into underlying pointer data and its relevant layout information (capacity, etc.).

• These kinds of methods can be marked as unsafe if constructing new values as trust is placed on the user to avoid conditions that might lead to undefined behavior.

  Such a case might be passing a pointer of sizeof T * 10 to Vec::from_raw_parts but also passing 20 as the capacity argument, which would lead to writing or accessing values 10 through 19 in the vector being undefined behavior.