RISC-V Emulated Testing
Adds a disabled docker image on which to run RISC-V tests. Based on the armhf image.
Test using
```
./src/ci/docker/run.sh riscv64gc-linux
```
cc: @msizanoen1
Complete the std::time documentation to warn about the inconsistencies between OS
Fixes#48980.
I put the new documentation in `src/libstd/time.rs` at the module-level because it affects all types, even the one that are not directly system dependents if they are used with affected types, but there may be a better place for it.
Since the docs for the WASI API are now evolving in [WebAssembly/WASI] repo,
I thought it might be useful to update the links in the docs to point to that location
instead of using the outdated `CraneStation/wasmtime` destination.
[WebAssembly/WASI]: https://github.com/WebAssembly/WASI
The link for UNIX was pointing to the Cloud ABI docs. It should have
been pointing to the clock_gettime docs instead. The table is repeated
in the docs for SystemTime, but there the UNIX entry was already correct.
`description` has been documented as soft-deprecated since 1.27.0 (17
months ago). There is no longer any reason to call it or implement it.
This commit:
- adds #[rustc_deprecated(since = "1.41.0")] to Error::description;
- moves description (and cause, which is also deprecated) below the
source and backtrace methods in the Error trait;
- reduces documentation of description and cause to take up much less
vertical real estate in rustdocs, while preserving the example that
shows how to render errors without needing to call description;
- removes the description function of all *currently unstable* Error
impls in the standard library;
- marks #[allow(deprecated)] the description function of all *stable*
Error impls in the standard library;
- replaces miscellaneous uses of description in example code and the
compiler.
Added table containing the system calls used by Instant and SystemTime.
# Description
See #32626 for a discussion on documenting system calls used by Instant and SystemTime.
## Changes
- Added a table containing the system calls used by each platform.
EDIT: If I can format this table better (due to the large links) please let me know.
I'd also be happy to learn a quick command to generate the docs on my host machine! Currently I am using: `python x.py doc --stage 0 src/libstd` but that gives me some `unrecognized intrinsic` errors. Advice is always welcome :)
closes#32626
Turn duration consts into associated consts
As suggested in https://github.com/rust-lang/rust/issues/57391#issuecomment-459658236, I'm moving `Duration` constants (`SECOND`, `MILLISECOND` and so on; currently behind unstable `duration_constants` feature) into the `impl Duration` block.
cc @frewsxcv @SimonSapin
Right now we do unit conversions between PerfCounter measurements
and nanoseconds for every add/sub we do between Durations and Instants
on Windows machines. This leads to goofy behavior, like this snippet
failing:
```
let now = Instant::now();
let offset = Duration::from_millis(5);
assert_eq!((now + offset) - now, (now - now) + offset);
```
with precision problems like this:
```
thread 'main' panicked at 'assertion failed: `(left == right)`
left: `4.999914ms`,
right: `5ms`', src\main.rs:6:5
```
To fix it, this changeset does the unit conversion once, when we
measure the clock, and all the subsequent math in u64 nanoseconds.
It also adds an exact associativity test to the `sys/time.rs`
test suite to make sure we don't regress on this in the future.
std: Force `Instant::now()` to be monotonic
This commit is an attempt to force `Instant::now` to be monotonic
through any means possible. We tried relying on OS/hardware/clock
implementations, but those seem buggy enough that we can't rely on them
in practice. This commit implements the same hammer Firefox recently
implemented (noted in #56612) which is to just keep whatever the lastest
`Instant::now()` return value was in memory, returning that instead of
the OS looks like it's moving backwards.
Closes#48514Closes#49281
cc #51648
cc #56560Closes#56612Closes#56940
This commit is an attempt to force `Instant::now` to be monotonic
through any means possible. We tried relying on OS/hardware/clock
implementations, but those seem buggy enough that we can't rely on them
in practice. This commit implements the same hammer Firefox recently
implemented (noted in #56612) which is to just keep whatever the lastest
`Instant::now()` return value was in memory, returning that instead of
the OS looks like it's moving backwards.
Closes#48514Closes#49281
cc #51648
cc #56560Closes#56612Closes#56940
Add duration constants
Add constants `SECOND`, `MILLISECOND`, `MICROSECOND`, and `NANOSECOND` to `core::time`.
This will make working with durations more ergonomic. Compare:
```rust
// Convenient, but deprecated function.
thread::sleep_ms(2000);
// The current canonical way to sleep for two seconds.
thread::sleep(Duration::from_secs(2));
// Sleeping using one of the new constants.
thread::sleep(2 * SECOND);
```
Eliminate Receiver::recv_timeout panic
Fixes#54552.
This panic is because `recv_timeout` uses `Instant::now() + timeout` internally. This possible panic is not mentioned in the documentation for this method.
Very recently we merged (still unstable) support for checked addition (#56490) of `Instant + Duration`, so it's now finally possible to add these together without risking a panic.
