leakyvec

A header-only unsafe C++17 wrapper around a std::vector that allows leaking its memory.

Why?

I came across the need to transfer memory ownership of a C++ std::vector to a Rust Vec in another project. But std::vector doesn't provide a way to leak its memory, and allocators are "fun", especially when crossing language boundaries.

This is mostly just an experiment to see if it's possible; I'm not sure I'd recommend using this.

Usage example

#include <leakyvec/leakyvec.hpp>

auto vec = std::vector<int>{1, 2, 3, 4};
auto leaky_vec = leaky::Vec<int>(std::move(vec));
auto parts = leaky_vec.leak();

// Either transfer ownership back to a std::vector like so:
auto leaky_vec2 = leaky::Vec<int>::from_parts(parts);
auto vec2 = leaky_vec2.take();

// ... or manually delete the leaked memory with the allocator:
auto [data, size, capacity, allocator] = parts;
alloc.deallocate(data, capacity);

// But don't do both! :)

Demo transferring memory ownership from C++ to Rust

• TODO: Demo transferring memory ownership from a C++ std::vector allocated with the default allocator into a Rust Vec using the default global allocator.
• TODO: Demo transferring memory ownership using non-default allocators (requires nightly Rust to work with unstable allocator APIs).

How to build and install?

cmake -B build
DESTDIR=$PWD/build/install cmake --build build --target install

How to build and run the tests?

Install the googletest dependency:

sudo dnf install gmock-devel    # Fedora
sudo apt install libgmock-dev   # Ubuntu

Build and run the tests:

cmake -B build -DBUILD_TESTING=ON
cmake --build build --parallel
ctest --test-dir build          # Use CTest
./build/tests/leakyvec-tests    # Run the test binary directly

How to run the tests with ASAN / UBSAN?

Add -DLEAKY_USE_ASAN=ON or -DLEAKY_USE_UBSAN=ON to the CMake command above. You need to delete the build directory and reconfigure CMake after changing these options.