[AnIdiotOnTheNet]

I don't think that's as hard as you make it out to be. Notably, Zig does not have a default allocator and its standard library is written accordingly, making it trivial to ensure the use of the appropriate allocation strategy for any given task, including using a debug allocator that tracks double-free and memory leaks.

[pjmlp]

Has Zig already sorted out the use-after-free story?

[AnIdiotOnTheNet]

No, and as far as I am aware it makes no attempt to do so other than some allocators overwriting freed memory with a known signature in debug modes so the problem is more obvious.