use unstable feature 'arc_unwrap_or_clone'

[BruceChar]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

/// Cargo.toml
[dependencies]
polars = { version = "0.38.2", features = ["lazy", "csv"] }

/// use polars
use polars_core::prelude::*;
use polars_io::prelude::*;
use std::fs::File;

let df = CsvReader::from_path("./wtf.csv")
        .unwrap()
        .finish()
        .unwrap();

Log output

Compiling polars-lazy v0.38.2
error[E0658]: use of unstable library feature 'arc_unwrap_or_clone'
  --> /Users/bruce/.cargo/registry/src/mirrors.ustc.edu.cn-61ef6e0cd06fb9b8/polars-lazy-0.38.2/src/physical_plan/executors/scan/csv.rs:21:18
   |
21 |             .map(Arc::unwrap_or_clone);
   |                  ^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #93610 <https://github.com/rust-lang/rust/issues/93610> for more information

For more information about this error, try `rustc --explain E0658`.
error: could not compile `polars-lazy` (lib) due to previous error

### Issue description

can not run polars with CsvReader::from_path

### Expected behavior

data frame from csv file

### Installed versions

<details>

active toolchain
----------------

stable-aarch64-apple-darwin (default)
rustc 1.74.1 (a28077b28 2023-12-04)

polars = 0.38.2


</details>

[ritchie46]

@mickvangelderen can you revert that one? I now know the reason you just learned about it ;)

[ritchie46]

@BruceChar can you update your compiler to latest stable?

[BruceChar]

@BruceChar can you update your compiler to latest stable?

It works fine after update rust to latest version, except the polars_core & polars_io undeclared .Maybe the document need update too

[mickvangelderen]

Hey @BruceChar, sorry for the inconvenience. This is the PR that introduces this change #14837. In the PR I mention that this change would require rustc 1.76+.

@ritchie46 What is the MSRV policy of polars?

Here is an immediate fix: #14981

[mickvangelderen]

We discussed internally and our MSRV is latest stable. Since the code compiles on that version, this is not a bug. The solution is to update the compiler.