support generic output

[biryukovmaxim]

📦 PR: Generalize patch output buffer to support AlignedVec and other custom writers

✨ Summary

This PR generalizes the patch function’s output buffer parameter (new) from a fixed &mut Vec<u8> to any type that implements:

• std::io::Write — for writing patch data,
• DerefMut<Target = [u8]> — for in-place mutation of the diff section.

This allows the function to be used with buffer types like AlignedVec, which provide memory alignment guarantees required for later reinterpretation (e.g., casting to typed data).

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🧪 What Changed

• Signature change:

  - pub fn patch<T: Read>(..., new: &mut Vec<u8>)
  + pub fn patch<T: Read, W: Write + DerefMut<Target = [u8]>>(..., new: &mut W)

⚠️ Breaking Change: Type Inference

let mut buf = Default::default();
patch(old, &mut patch_data, &mut buf); // ❌ may fail to infer `Vec<u8>`

Developers may now need to explicitly specify the type:

let mut buf: Vec<u8> = Default::default();

✅ Benefits

• Supports memory-aligned buffers like AlignedVec.
• Enables more flexible and performant downstream use cases (e.g., reinterpreting as typed memory).
• Maintains all behavior of the original patch logic.

Let me know if you want a version with a fallback function to keep compatibility for existing callers.

[kornelski]

Thanks for the PR!

Please add documentation and perhaps an example that it works with a &mut Vec, because the trait bounds don't make that obvious.

[biryukovmaxim]

d8fa1bd