Update emscripten std tests
This disables a bunch of emscripten tests that test things emscripten doesn't support and re-enables a whole bunch of tests which now work just fine on emscripten.
Tested with `EMCC_CFLAGS="-s MAXIMUM_MEMORY=2GB" ./x.py test library/ --target wasm32-unknown-emscripten`.
- Simplify some of the language
- Minor grammar fixes
- Don't imply that pipes *only* work across multiple processes; instead,
*suggest* that they're typically used across two or more separate
processes.
- Specify that portable applications cannot use multiple readers or
multiple writers for messages larger than a byte, due to potential
interleaving.
- Remove no-longer-referenced footnote URLs.
Stabilize `std::io::ErrorKind::CrossesDevices`
FCP in #130191
cc #86442
See #130191 for more info and a recap of what has happened up until now.
TLDR: This had been FCP'd in December 2022 with some other `ErrorKind`s, but the stabilization got postponed due to some concerns voiced about several of the variants. However, the only concern ever voiced for this variant in particular was a wish to rename this to `NotSameDevice` analogous to Windows's `ERROR_NOT_SAME_DEVICE` (as opposed to Unix's `EXDEV`). This suggestion did not receive any support. So let's try to FCP this as is.
r? libs-api
Mark `get_mut` and `set_position` in `std::io::Cursor` as const.
Relevant tracking issue: #130801
The methods `get_mut` and `set_position` can trivially be marked as const due to #57349 being stabilised.
Mark some more types as having insignificant dtor
These were caught by https://github.com/rust-lang/rust/pull/129864#issuecomment-2376658407, which is implementing a lint for some changes in drop order for temporaries in tail expressions.
Specifically, the destructors of `CString` and the bitpacked repr for `std::io::Error` are insignificant insofar as they don't have side-effects on things like locking or synchronization; they just free memory.
See some discussion on #89144 for what makes a drop impl "significant"
Add `File` constructors that return files wrapped with a buffer
In addition to the light convenience, these are intended to raise visibility that buffering is something you should consider when opening a file, since unbuffered I/O is a common performance footgun to Rust newcomers.
ACP: https://github.com/rust-lang/libs-team/issues/446
Tracking Issue: #130804
Also emit `missing_docs` lint with `--test` to fulfil expectations
This PR removes the "test harness" suppression of the `missing_docs` lint to be able to fulfil `#[expect]` (expectations) as it is now "relevant".
I think the goal was to maybe avoid false-positive while linting on public items under `#[cfg(test)]` but with effective visibility we should no longer have any false-positive.
Another possibility would be to query the lint level and only emit the lint if it's of expect level, but that is even more hacky.
Fixes https://github.com/rust-lang/rust/issues/130021
try-job: x86_64-gnu-aux
Stabilize most of `io_error_more`
Sadly, venting my frustration with t-libs-api is not a constructive way to solve problems and get things done, so I will try to stick to stuff that actually matters here.
- Tracking issue for this feature was opened 3 years ago: #86442
- FCP to stabilize it was completed 19(!!) months ago: https://github.com/rust-lang/rust/issues/86442#issuecomment-1368082102
- A PR with stabilization was similarly open for 19 months: #106375, but nothing ever came out of it. Presumably (it is hard to judge given the lack of communication) because a few of the variants still had some concerns voiced about them, even after the FCP.
So, to highlight a common sentiment:
> Maybe uncontroversial variants can be stabilised first and other variants (such as `QuotaExceeded` or `FilesystemLoop`) later? [^1]
[^1]: https://github.com/rust-lang/rust/issues/106375#issuecomment-1435762236
> I would like to voice support stabilization of the uncontroversial variants. This would get those variants to stable and focus the discussion around the more controversial ones. I don't see any particular reason that all of these must be stabilized at the same time. [...] [^2]
[^2]: https://github.com/rust-lang/rust/pull/106375#issuecomment-1742661555
> Maybe some less-controversial subset could be stabilized sooner? What’s blocking this issue from making progress? [^3]
[^3]: https://github.com/rust-lang/rust/issues/86442#issuecomment-1691187483 (got 30 upvotes btw) (and no response)
So this is exactly what this PR does. It stabilizes the non-controversial variants now, leaving just a few of them behind.
Namely, this PR stabilizes:
- `HostUnreachable`
- `NetworkUnreachable`
- `NetworkDown`
- `NotADirectory`
- `IsADirectory`
- `DirectoryNotEmpty`
- `ReadOnlyFilesystem`
- `StaleNetworkFileHandle`
- `StorageFull`
- `NotSeekable`
- `FileTooLarge`
- `ResourceBusy`
- `ExecutableFileBusy`
- `Deadlock`
- `TooManyLinks`
- `ArgumentListTooLong`
- `Unsupported`
This PR does not stabilize:
- `FilesystemLoop`
- `FilesystemQuotaExceeded`
- `CrossesDevices`
- `InvalidFilename`
Hopefully, this will allow us to move forward with this highly and long awaited addition to std, both allowing to still polish the less clear parts of it and not leading to stagnation.
r? joshtriplett
because they seem to be listed as a part of t-libs-api and were one of the most responsive persons previously
