[jira] [Created] (ARROW-10002) [Rust] Trait-specialization requries nightly

["Kyle Strand (Jira)" <ji...@apache.org>]

Kyle Strand created ARROW-10002:
-----------------------------------

             Summary: [Rust] Trait-specialization requries nightly
                 Key: ARROW-10002
                 URL: https://issues.apache.org/jira/browse/ARROW-10002
             Project: Apache Arrow
          Issue Type: Sub-task
          Components: Rust
            Reporter: Kyle Strand


Trait specialization is widely used in the Rust Arrow implementation. Uses can be identified by searching for instances of `default fn` in the codebase:

```
$> rg -c 'default fn' ../arrow/rust/
../arrow/rust/parquet/src/util/test_common/rand_gen.rs:1
../arrow/rust/parquet/src/column/writer.rs:2
../arrow/rust/parquet/src/encodings/encoding.rs:16
../arrow/rust/parquet/src/arrow/record_reader.rs:1
../arrow/rust/parquet/src/encodings/decoding.rs:13
../arrow/rust/parquet/src/file/statistics.rs:1
../arrow/rust/arrow/src/array/builder.rs:7
../arrow/rust/arrow/src/array/array.rs:3
../arrow/rust/arrow/src/array/equal.rs:3
```

This feature requires Nightly Rust. Additionally, there is [no schedule for stabilization|https://github.com/rust-lang/rust/issues/31844#issue-135807289] , primarily due to an [unresolved soundness hole|[http://aturon.github.io/blog/2017/07/08/lifetime-dispatch]. (Note: there has been further discussion and ideas for resolving the soundness issue, but to my knowledge no definitive action.)|http://aturon.github.io/tech/2017/07/08/lifetime-dispatch/].]

If we can remove specialization from the Rust codebase, we will not be blocked on the Rust team's stabilization of that feature in order to move to stable Rust.



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