Getting a slice out of an ArrayView: cannot return value referencing function parameter

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
rust
Domain
data

Research direction

Start with the minimal Rust example and the call at simulate/src/system_serialization.rs:58. Read the ArrayView, as_slice_memory_order, and aview1 definitions to understand the lifetime relationship, then reproduce the compiler error with the reported example. Done means establishing a supported way to construct the one-dimensional view, or documenting why the attempted conversion cannot compile.

Written by the indexing model from the issue text.

Description

I am trying to write a function that interprets an ArrayView as row major order, but Rust doesn't like me extracting the slice underlying the ArrayView. Here is a mimimal example showing the problem:

fn as_standard_view<'a, T>(a: ArrayView<'a, T, Ix2>) -> ArrayView<'a, T, Ix1> {
    let slice = a.as_slice_memory_order().unwrap();
    aview1(slice)
}

This is the associated error:

error[E0515]: cannot return value referencing function parameter `a`
  --> simulate/src/system_serialization.rs:58:5
   |
57 |     let slice = a.as_slice_memory_order().unwrap();
   |                 - `a` is borrowed here
58 |     aview1(slice)
   |     ^^^^^^^^^^^^^ returns a value referencing data owned by the current function

I do understand the error, but I am not sure how to work around it. After all, the slice is held by the ArrayView, but not the data itself.

Any idea how to construct thay ArrayView without rust thinking that I am trying to reference something inside the function?

Dominant language
Rust
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