Global variables (unacceptable; warrants the "bug" label):

What the hell is this comment doing here?

Requiring an allocator:

This implementation is so problematic precisely because it was ported. We can do better by writing these functions from first principles, using Zig's guiding principles and it will be more robust, optimal, and reusable.

In order to close this issue:

1. Delete the existing deflate/inflate implementation
2. Make a new implementation that does not require passing an Allocator and is not based on porting existing code. It's ok to look at existing code for inspiration, however. It's fun, and not as hard as you would think. Think about how to do it from first principles and I promise you will make a better implementation than the Go std lib authors.
3. Suggestion: take advantage of Zig's SIMD features
4. Provide benchmarks that show the new implementation is significantly faster, better, etc.

Related:

• Deflate wrong result #17863