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Tracking Issue for read_array #148848
Description
Feature gate: #![feature(read_array)]
This is a tracking issue for the read_array feature, which provides the Read::read_array method.
Public API
// std::io
impl Read {
fn read_array<N: usize>(&mut self) -> Result<[u8; N]>
where
Self: Sized,
{
/* ... */
}
}Steps / History
(Remember to update the S-tracking-* label when checking boxes.)
- ACP:
std::io::Readprovides byte-order reading trait libs-team#691 (which inspired subsequent @rust-lang/libs-api design) - Implementation: Implement
Read::read_array#148850 - Final comment period (FCP)1
- Stabilization PR
Unresolved Questions
- None yet.
Activity
Implement `Read::read_array`
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Unrolled build for #148850
lyphyser commentedon Nov 26, 2025
I think this should return an ArrayVec equivalent (in which case the caller would chain a try_into() to get a plain array if they want).
Currently, it throws away data if there is some data available but not enough to fill the array, which is not a good interface.
It would be even more general to take an ArrayVec by &mut reference, and even more general some trait that can take both a Vec and an ArrayVec.
Amanieu commentedon Nov 27, 2025
This is intended to be used like
read_exactwhere you expect a certain number of bytes and any early EOF should be treated as an error (and the corresponding bytes simply dropped). If you need to handle early EOF then you should be usingreadinstead of this.Implement `Read::read_array`
Rollup merge of rust-lang#148850 - joshtriplett:read-array, r=joboet
Amanieu commentedon Dec 9, 2025
This should only be stabilized as a
finalmethod as per rust-lang/rfcs#3678. This will allowread_arrayto work ondyn Readtypes.thaliaarchi commentedon Jun 26, 2026
@Amanieu Why does whether
read_arraycan be overridden have any bearing on it working ondyn Readtypes?Besides that, I don't think it absolutely needs to be
final. For example, someone may want to eliminate the potential panic if they can guarantee correctness ofread_buf_exact.Amanieu commentedon Jun 26, 2026
In order to keep
Readdyn-compatible we would need to addwhere Self: Sizedbounds to the method so it doesn't get included in the vtable. However it then becomes impossible to use this method with adyn Read. If we want this method to be available ondyn Readthen it must be afinal fn, and that's not something we can do in the future in a backwards-compatible manner.