[ridiculous_fish]

I think this doesn't work because `aligned + size` may wrap all the way around into the valid region again. For example if aligned == ptr + 1, and size is usize::MAX, we will end up with new_ptr == ptr and the allocation will wrongly succeed.

[dev_dwarf]

Interesting point. I modified my example to test what you described. I had to play with the compilation flags to get the allocs to not be optimized out and to not panic when the integer overflow happens, but otherwise I didn't change the logic. I'm pretty sure my implementation is correctly handling the case you mention, evidenced by it returning a null pointer.

Link: https://godbolt.org/z/f1jGW6Pa3

Update: NVM, definitely not being handled correctly. https://godbolt.org/z/cMTe1o979

[loeg]

The straightforward answer is: don't tolerate ridiculous alignments.

[saagarjha]

You'd need to check for that, though.

[loeg]

No, just restrict the domain of the alignment input to like, u8. Maybe u16. Either way, it is easy to ensure your bump allocation space is far enough away from SIZE_MAX.