This commit adds a new entry to the Travis matrix which will execute emscripten
test suites. Along the way it updates a few bits of the test suite to continue
passing on emscripten, such as:
* Ignoring i128/u128 tests as they're presumably just not working (didn't
investigate as to why)
* Disabling a few process tests (not working on emscripten)
* Ignore some num tests in libstd (#39119)
* Fix some warnings when compiling
Show a conventional way to use process::exit when destructors are considered important and also
mention that the same caveats wrt destructors apply to exec as well.
fs::metadata() follows symlinks so is_symlink() will always return
false. Use symlink_metadata instead in the example in the
documentation.
See issue #39088.
PartialEq and PartialOrd between IpAddr and Ipv[46]Addr.
PartialEq was rather useful, so, I figured that I'd implement it. I added PartialOrd for good measure.
Minor improvements to docs in std::env structures/functions.
* Call functions "functions" instead of "methods".
* Link structures to their constructor functions
* Add other misc. documentation links
`ToSocketAddrs` is implemented for a number of different types,
including `(IpAddr, u16)`, `&str`, and various others, for the
convenience of being able to run things like
`TcpListener::bind("10.11.12.13:1415")`. However, because this is a
generic parameter with a trait bound, if you have a `String` you cannot
pass it in, either directly as `TcpListener::bind(string)`, or the
`TcpListener::bind(&string)` as you might expect due to deref coercion;
you have to use `TcpListener::bind(&*string)`, which is noisy and hard
to discover (though #39029 suggests better error messages to make it
more discoverable).
Rather than making people stumble over this, just implement
`ToSocketAddrs` for `String`.
std/net/udp: Improve set_nonblocking test
While writing a separate change, I noticed the current test for `UdpSocket::set_nonblocking()` is fairly ineffective.
This fixes the test so that it validates that a correct error is returned on calls to `recv()` when no data is available.
std: Ignore close_read_wakes_up on Windows
It looks like in practice at least this test will not pass on Windows.
Empirically it is prone to blocking forever, presumably because a call to
`shutdown` doesn't actually wake up other threads on Windows.
We don't document this as a guarantee for `shutdown`, nor do we internally rely
on it. This test originated in a time long since passed when it was leveraged
for canceling I/O, but nowadays there's nothing fancy happening in the standard
library so it's not really a productive test anyway, hence just ignoring it on
Windows.
Closes#31657
* give the new feature its own feature tag
* correct a lifetime problem in the test
* use .output() instead of .spawn() in the test so that output is
actually collected
* correct the same error in the test whose skeleton I cribbed
std: Add a nonblocking `Child::try_wait` method
This commit adds a new method to the `Child` type in the `std::process` module
called `try_wait`. This method is the same as `wait` except that it will not
block the calling thread and instead only attempt to collect the exit status. On
Unix this means that we call `waitpid` with the `WNOHANG` flag and on Windows it
just means that we pass a 0 timeout to `WaitForSingleObject`.
Currently it's possible to build this method out of tree, but it's unfortunately
tricky to do so. Specifically on Unix you essentially lose ownership of the pid
for the process once a call to `waitpid` has succeeded. Although `Child` tracks
this state internally to be resilient to multiple calls to `wait` or a `kill`
after a successful wait, if the child is waited on externally then the state
inside of `Child` is not updated. This means that external implementations of
this method must be extra careful to essentially not use a `Child`'s methods
after a call to `waitpid` has succeeded (even in a nonblocking fashion).
By adding this functionality to the standard library it should help canonicalize
these external implementations and ensure they can continue to robustly reuse
the `Child` type from the standard library without worrying about pid ownership.
Symlink creation on Windows has in the past basically required admin;
it’s being opened up a bit in the Creators Update, so that at least
people who have put their computers into Developer Mode will be able to
create symlinks without special privileges. (Microsoft are being
cautious about it all; the Developer Mode requirement makes it so that
it this won’t be as helpful as I’d like, but it’s still an improvement
over requiring admin.)
Because of compatibility concerns, they’ve hidden this new functionality
behind a new flag in the CreateSymbolicLink dwFlags:
SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE. So we add this flag in
order to join the party.
Older Windows doesn’t like this new flag, though, so if we encounter
ERROR_INVALID_PARAMETER we try again without the new flag.
Sources:
- https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/
is the official announcement (search for CreateSymbolicLink)
- https://news.ycombinator.com/item?id=13096354 on why the new flag.
- https://twitter.com/richturn_ms/status/818167548269051905 confirming
that Developer Mode will still be required.
Remove not(stage0) from deny(warnings)
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
This commit adds a new method to the `Child` type in the `std::process` module
called `try_wait`. This method is the same as `wait` except that it will not
block the calling thread and instead only attempt to collect the exit status. On
Unix this means that we call `waitpid` with the `WNOHANG` flag and on Windows it
just means that we pass a 0 timeout to `WaitForSingleObject`.
Currently it's possible to build this method out of tree, but it's unfortunately
tricky to do so. Specifically on Unix you essentially lose ownership of the pid
for the process once a call to `waitpid` has succeeded. Although `Child` tracks
this state internally to be resilient to multiple calls to `wait` or a `kill`
after a successful wait, if the child is waited on externally then the state
inside of `Child` is not updated. This means that external implementations of
this method must be extra careful to essentially not use a `Child`'s methods
after a call to `waitpid` has succeeded (even in a nonblocking fashion).
By adding this functionality to the standard library it should help canonicalize
these external implementations and ensure they can continue to robustly reuse
the `Child` type from the standard library without worrying about pid ownership.
std: Don't pass overlapped handles to processes
This commit fixes a mistake introduced in #31618 where overlapped handles were
leaked to child processes on Windows. On Windows once a handle is in overlapped
mode it should always have I/O executed with an instance of `OVERLAPPED`. Most
child processes, however, are not prepared to have their stdio handles in
overlapped mode as they don't use `OVERLAPPED` on reads/writes to the handle.
Now we haven't had any odd behavior in Rust up to this point, and the original
bug was introduced almost a year ago. I believe this is because it turns out
that if you *don't* pass an `OVERLAPPED` then the system will [supply one for
you][link]. In this case everything will go awry if you concurrently operate on
the handle. In Rust, however, the stdio handles are always locked, and there's
no way to not use them unlocked in libstd. Due to that change we've always had
synchronized access to these handles, which means that Rust programs typically
"just work".
Conversely, though, this commit fixes the test case included, which exhibits
behavior that other programs Rust spawns may attempt to execute. Namely, the
stdio handles may be concurrently used and having them in overlapped mode wreaks
havoc.
[link]: https://blogs.msdn.microsoft.com/oldnewthing/20121012-00/?p=6343Closes#38811
It looks like in practice at least this test will not pass on Windows.
Empirically it is prone to blocking forever, presumably because a call to
`shutdown` doesn't actually wake up other threads on Windows.
We don't document this as a guarantee for `shutdown`, nor do we internally rely
on it. This test originated in a time long since passed when it was leveraged
for canceling I/O, but nowadays there's nothing fancy happening in the standard
library so it's not really a productive test anyway, hence just ignoring it on
Windows.
Closes#31657
