Optimize some functions in std::process
* Be sure that `read_to_end` gets directed towards `read_to_end_uninitialized` for all handles
* When spawning a child that guaranteed doesn't need a stdin, don't actually create a stdin pipe for that process, instead just redirect it to /dev/null
* When calling `wait_with_output`, don't spawn threads to read out the pipes of the child. Instead drain all pipes on the calling thread and *then* wait on the process.
Functionally, it is intended that nothing changes as part of this PR
---
Note that this was the same as #31613, and even after that it turned out that fixing Windows was easier than I thought! To copy a comment from over there:
> As some rationale for this as well, it's always bothered me that we've spawned threads in the standard library for this (seems a bit overkill), and I've also been curious lately as to our why our build times for Windows are so much higher than Unix (on the buildbots we have). I have done basically 0 investigation into why, but I figured it can't help to try to optimize Command::output which I believe is called quite a few times during the test suite.
collections: Fix broken doc example
PR #32135 was accidentally merged without tests passing, and unfortunately one
of the tests added was broken, so this fixes that.
Semantically there's actually no reason for us to spawn threads as part of the
call to `wait_with_output`, and that's generally an incredibly heavyweight
operation for just reading a few bytes (especially when stderr probably rarely
has bytes!). An equivalent operation in terms of what's implemented today would
be to just drain both pipes of all contents and then call `wait` on the child
process itself.
On Unix we can implement this through some convenient use of the `select`
function, whereas on Windows we can make use of overlapped I/O. Note that on
Windows this requires us to use named pipes instead of anonymous pipes, but
they're semantically the same under the hood.
Fix incorrect trait privacy error
This PR fixes#21670 by using the crate metadata instead of `ExternalExports` to determine if an external item is public.
r? @nikomatsakis
Make errors for unnecessary visibility qualifiers consistent
This PR refactors away `syntax::parse::parser::ParsePub` so that unnecessary visibility qualifiers on variant fields are reported not by the parser but by `privacy::SanePrivacyVisitor` (thanks to @petrochenkov's drive-by improvements in #31919).
r? @nikomatsakis
tests: add test for empty <>
Rust allows to specify an empty list of type and lifetime parameters, but there are no tests for it:
```
user@UNIT-326 [12:53:45] [~/projects/rust] [diamonds-and-rust]
-> % grep "<>" -R src/test
src/test/compile-fail/generic-type-params-name-repr.rs: // And don't print <> at all when there's just defaults.
src/test/debuginfo/issue22656.rs:// when trying to handle a Vec<> or anything else that contains zero-sized
```
So let's add them! Besides it's such a wonderful opportunity to put a reference to Judas Priest band into the branch name ;)
For example if `Command::output` or `Command::status` is used then stdin is just
immediately closed. Add an option for this so as an optimization we can avoid
creating pipes entirely.
This should help reduce the number of active file descriptors when spawning
processes on Unix and the number of active handles on Windows.
This pushes the implementation detail of proxying `read_to_end` through to
`read_to_end_uninitialized` all the way down to the `FileDesc` and `Handle`
implementations on Unix/Windows. This way intermediate layers will also be able
to take advantage of this optimized implementation.
This commit also adds the optimized implementation for `ChildStdout` and
`ChildStderr`.
As part of the ongoing effort to document all methods with examples,
this commit adds the missing examples for the `BTreeMap` collection
type.
This is part of issue #29348.
Clarify documentation for string slicing (Index impls)
Clarify documentation for string slicing (Index impls)
- Mention the sugared syntax for the implementations, since it's not
apparent from the docs that `Index<Range<usize>>` corresponds to
`&self[a..b]`.
- Be specific in that start <= end and end <= len
This is just one fix in response to #32057
Clarify the semantics of enum discriminants
cf. https://doc.rust-lang.org/error-index.html#E0082
> The default type for enum discriminants is isize, but it can be adjusted by adding the repr attribute to the enum declaration.
It would be great if anyone could check my English.
mk: Distribute fewer TARGET_CRATES
Right now everything in TARGET_CRATES is built by default for all non-fulldeps
tests and is distributed by default for all target standard library packages.
Currenly this includes a number of unstable crates which are rarely used such as
`graphviz` and `rbml`>
This commit trims down the set of `TARGET_CRATES`, moves a number of tests to
`*-fulldeps` as a result, and trims down the dependencies of libtest so we can
distribute fewer crates in the `rust-std` packages.
Add error file for E0152
It completes #31818.
However it is not complete yet:
* test will need to be updated
* the file name displayed is a bit too unclear.
I'm not sure yet what's the "correct" file name to display. If anyone has an idea on this, it'd be very appreciated.
r? @brson
implement the `?` operator
The `?` postfix operator is sugar equivalent to the try! macro, but is more amenable to chaining:
`File::open("foo")?.metadata()?.is_dir()`.
`?` is accepted on any *expression* that can return a `Result`, e.g. `x()?`, `y!()?`, `{z}?`,
`(w)?`, etc. And binds more tightly than unary operators, e.g. `!x?` is parsed as `!(x?)`.
cc #31436
---
cc @aturon @eddyb
Fix building libstd on emscripten targets.
The main cause of the problem is that libstd/os/mod.rs treats emscripten targets as an alias of linux targets, whereas liblibc treats emscripten targets as musl-compliant, so it gets a slightly different struct stat64 defined.
This commit adds conditional compilation checks to use the correct timestamp format on fs metadata functions in the case of compiling to emscripten targets.
This commit also depends needs f1575cff2d applied in order to successfully build libstd with emscripten target.
Right now everything in TARGET_CRATES is built by default for all non-fulldeps
tests and is distributed by default for all target standard library packages.
Currenly this includes a number of unstable crates which are rarely used such as
`graphviz` and `rbml`>
This commit trims down the set of `TARGET_CRATES`, moves a number of tests to
`*-fulldeps` as a result, and trims down the dependencies of libtest so we can
distribute fewer crates in the `rust-std` packages.
- Mention the sugared syntax for the implementations, since it's not
apparent from the docs that `Index<Range<usize>>` corresponds to
`&self[a..b]`.
- Be specific in that start <= end and end <= len
The `?` postfix operator is sugar equivalent to the try! macro, but is more amenable to chaining:
`File::open("foo")?.metadata()?.is_dir()`.
`?` is accepted on any *expression* that can return a `Result`, e.g. `x()?`, `y!()?`, `{z}?`,
`(w)?`, etc. And binds more tightly than unary operators, e.g. `!x?` is parsed as `!(x?)`.
cc #31436
- make sure we copy the third party objects (crt*.o) to the target stage directory.
- apply the x86_64-musl logic also to the i686-musl target.
---
r? @alexcrichton
Squashed 10 commits:
1) The main cause of the problem is that libstd/os/mod.rs treats emscripten targets as an alias of linux targets, whereas liblibc treats emscripten targets as musl-compliant, so it gets a slightly different struct stat64 defined.
This commit adds conditional compilation checks to use the correct timestamp format on fs metadata functions in the case of compiling to emscripten targets.
2) Update previous commit to comply with rust formatting standards.
Removed tab characters, remove trailing whitespaces.
3) Move emscripten changes into their own file under libstd/os/emscripten
Put libstd/os/linux/fs back to the way it was.
4) Cannot use stat.st_ctim on emscripten to get created time.
5) Remove compile-time conditionals for target_env = musl, it looks like musl builds compile fine already.
6) Undone some formatting changes that are no longer needed,
Removed some more target_env="musl" compilation checks that I missed from my previous commit.
7) upgrade to liblibc e19309c, it fixes the differences in the musl stat and stat64 definitions.
8) Undo the compile-time checks to check for emscripten (or musl targets) in the FileAttr struct.
No longer needed after updating liblibc to e19309c.
9) Change the MetadataExt implementation of emscripten fs.rs module to match the changes in new liblibc.
10) remove a stray return statement, should have been removed in the previous commit.
This adds support for fused multiply-add and multiply-subtract vector intrinsics for 128 and 256-bit vectors of `f32` and `f64`. These correspond to the intrinsics [listed here](https://software.intel.com/en-us/node/523929) except for the `_ss` and `_sd` variants. The intrinsics added are:
* `fmadd`
* `fmaddsub`
* `fmsub`
* `fmsubadd`
* `fnmadd`
* `fnmsub`
The “fma” target feature must be enabled by passing `-C target-feature=+fma` to rustc when using these, otherwise LLVM will complain.
I verified locally that the `x86_mm256_fmadd_ps` and `x86_mm256_fmsub_ps` work.
Fix panic on string slicing error to truncate the string
The string may be arbitrarily long, but we want to limit the panic
message to a reasonable length. Truncate the string if it is too long
(simply to char boundary).
Also add details to the start <= end message. I think it's ok to flesh
out the code here, since it's in a cold function.
Fixes#32063
Adding -Wno-error is more reliable and simple than trying to modify existing
flags. We've been using this in Debian already for the past few releases.
Making this change also encourages future maintainers towards "best practises".
Also take the opportunity to use the same method at all places in the file.
