This is much nicer for callers who want to short-circuit real I/O errors
with `?`, because they can write this
if let Some(status) = foo.try_wait()? {
...
} else {
...
}
instead of this
match foo.try_wait() {
Ok(status) => {
...
}
Err(err) if err.kind() == io::ErrorKind::WouldBlock => {
...
}
Err(err) => return Err(err),
}
The original design of `try_wait` was patterned after the `Read` and
`Write` traits, which support both blocking and non-blocking
implementations in a single API. But since `try_wait` is never blocking,
it makes sense to optimize for the non-blocking case.
Tracking issue: https://github.com/rust-lang/rust/issues/38903
Warning or error messages set via a lint group attribute
(e.g. `#[deny(warnings)]`) should still make it clear which individual
lint (by name) was triggered, similarly to how we include "on by
default" language for default lints. This—and, while we're here, the
existing "on by default" language—can be tucked into a note rather than
cluttering the main error message. This occasions the slightest of
refactorings (we now have to get the diagnostic-builder with the main
message first, before matching on the lint source).
This is in the matter of #36846.
Fix backtraces on i686-pc-windows-gnu by disabling FPO
This might have performance implications. But do note that MSVC
disables FPO by default nowadays and it's use is limited in exception
heavy languages like C++.
See discussion in: #39234Closes: #28218
This might have performance implications. But do note that MSVC
disables FPO by default nowadays and it's use is limited in exception
heavy languages like C++.
Closes: #28218
Make backtraces work on Windows GNU targets again.
This is done by adding a function that can return a filename
to pass to backtrace_create_state. The filename is obtained in
a safe way by first getting the filename, locking the file so it can't
be moved, and then getting the filename again and making sure it's the same.
See: https://github.com/rust-lang/rust/pull/37359#issuecomment-260123399
Issue: #33985
Note though that this isn't that pretty...
I had to implement a `WideCharToMultiByte` wrapper function to convert to the ANSI code page. This will work better than only allowing ASCII provided that the ANSI code page is set to the user's local language, which is often the case.
Also, please make sure that I didn't break the Unix build.
Perform lifetime elision (more) syntactically, before type-checking.
The *initial* goal of this patch was to remove the (contextual) `&RegionScope` argument passed around `rustc_typeck::astconv` and allow converting arbitrary (syntactic) `hir::Ty` to (semantic) `Ty`.
I've tried to closely match the existing behavior while moving the logic to the earlier `resolve_lifetime` pass, and [the crater report](https://gist.github.com/eddyb/4ac5b8516f87c1bfa2de528ed2b7779a) suggests none of the changes broke real code, but I will try to list everything:
There are few cases in lifetime elision that could trip users up due to "hidden knowledge":
```rust
type StaticStr = &'static str; // hides 'static
trait WithLifetime<'a> {
type Output; // can hide 'a
}
// This worked because the type of the first argument contains
// 'static, although StaticStr doesn't even have parameters.
fn foo(x: StaticStr) -> &str { x }
// This worked because the compiler resolved the argument type
// to <T as WithLifetime<'a>>::Output which has the hidden 'a.
fn bar<'a, T: WithLifetime<'a>>(_: T::Output) -> &str { "baz" }
```
In the two examples above, elision wasn't using lifetimes that were in the source, not even *needed* by paths in the source, but rather *happened* to be part of the semantic representation of the types.
To me, this suggests they should have never worked through elision (and they don't with this PR).
Next we have an actual rule with a strange result, that is, the return type here elides to `&'x str`:
```rust
impl<'a, 'b> Trait for Foo<'a, 'b> {
fn method<'x, 'y>(self: &'x Foo<'a, 'b>, _: Bar<'y>) -> &str {
&self.name
}
}
```
All 3 of `'a`, `'b` and `'y` are being ignored, because the `&self` elision rule only cares that the first argument is "`self` by reference". Due implementation considerations (elision running before typeck), I've limited it in this PR to a reference to a primitive/`struct`/`enum`/`union`, but not other types, but I am doing another crater run to assess the impact of limiting it to literally `&self` and `self: &Self` (they're identical in HIR).
It's probably ideal to keep an "implicit `Self` for `self`" type around and *only* apply the rule to `&self` itself, but that would result in more bikeshed, and #21400 suggests some people expect otherwise.
Another decent option is treating `self: X, ... -> Y` like `X -> Y` (one unique lifetime in `X` used for `Y`).
The remaining changes have to do with "object lifetime defaults" (see RFCs [599](https://github.com/rust-lang/rfcs/blob/master/text/0599-default-object-bound.md) and [1156](https://github.com/rust-lang/rfcs/blob/master/text/1156-adjust-default-object-bounds.md)):
```rust
trait Trait {}
struct Ref2<'a, 'b, T: 'a+'b>(&'a T, &'b T);
// These apply specifically within a (fn) body,
// which allows type and lifetime inference:
fn main() {
// Used to be &'a mut (Trait+'a) - where 'a is one
// inference variable - &'a mut (Trait+'b) in this PR.
let _: &mut Trait;
// Used to be an ambiguity error, but in this PR it's
// Ref2<'a, 'b, Trait+'c> (3 inference variables).
let _: Ref2<Trait>;
}
```
What's happening here is that inference variables are created on the fly by typeck whenever a lifetime has no resolution attached to it - while it would be possible to alter the implementation to reuse inference variables based on decisions made early by `resolve_lifetime`, not doing that is more flexible and works better - it can compile all testcases from #38624 by not ending up with `&'static mut (Trait+'static)`.
The ambiguity specifically cannot be an early error, because this is only the "default" (typeck can still pick something better based on the definition of `Trait` and whether it has any lifetime bounds), and having an error at all doesn't help anyone, as we can perfectly infer an appropriate lifetime inside the `fn` body.
**TODO**: write tests for the user-visible changes.
cc @nikomatsakis @arielb1
Add std::process::Command::envs()
`Command::envs()` adds a vector of key-value pairs to the child
process environment all at once. Suggested in #38526.
This is not fully baked and frankly I'm not sure it even _works_, but I need some help finishing it up, and this is the simplest way to show you what I've got. The problems I know exist and don't know how to solve, from most to least important, are:
* [ ] I don't know if the type signature of the new function is correct.
* [x] The new test might not be getting run. I didn't see it go by in the output of `x.py test src/libstd --stage 1`.
* [x] The tidy check says ``process.rs:402: different `since` than before`` which I don't know what it means.
r? @brson
exclusive range patterns
adds `..` patterns to the language under a feature gate (`exclusive_range_pattern`).
This allows turning
``` rust
match i {
0...9 => {},
10...19 => {},
20...29 => {},
_ => {}
}
```
into
``` rust
match i {
0..10 => {},
10..20 => {},
20..30 => {},
_ => {}
}
```
This is done by adding a function that can return a filename
to pass to backtrace_create_state. The filename is obtained in
a safe way by first getting the filename, locking the file so it can't
be moved, and then getting the filename again and making sure it's the same.
See: https://github.com/rust-lang/rust/pull/37359#issuecomment-260123399
Issue: #33985
* Command::envs() now takes anything that is IntoIterator<Item=(K, V)>
where both K and V are AsRef<OsStr>.
* Since we're not 100% sure that's the right signature, envs() is
now marked unstable. (You can use envs() with HashMap<str, str> but
not Vec<(str, str)>, for instance.)
* Update the test to match.
* By analogy, args() now takes any IntoIterator<Item=S>, S: AsRef<OsStr>.
This should be uncontroversial.
Add regression test for debuginfo + LTO
Fixes#25270, which cannot be reproduced with the current nightly version of the compiler anymore (due to various fixes to debuginfo generation in the past).
Should we run into the "possible ODR violation" again, the test added by this PR can be extend with the new case.
r? @alexcrichton
travis: Get an emscripten builder online
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
travis: Add i586 linux and i686 musl
This commit expands the existing x86_64-musl entry in the Travis matrix to also
build/test i586-unknown-linux-gnu and i686-unknown-linux-musl.
cc #38531Closes#35599Closes#39053
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
This commit expands the existing x86_64-musl entry in the Travis matrix to also
build/test i586-unknown-linux-gnu and i686-unknown-linux-musl.
cc #38531Closes#39053
Fix two const-eval issues related to i128 negation
First issue here was the fact that we’d only allow negating integers in i64 range in case the
integer was not infered yes. While this is not the direct cause of the issue, its still good to fix
it.
The real issue here is the code handling specifically the `min_value` literals. While I128_OVERFLOW
has the expected value (0x8000_..._0000), match using this value as a pattern is handled
incorrectly by the stage1 compiler (it seems to be handled correctly, by the stage2 compiler). So
what we do here is extract this pattern into an explicit `==` until the next snapshot.
Fixes#38987
First issue here was the fact that we’d only allow negating integers in i64 range in case the
integer was not infered yes. While this is not the direct cause of the issue, its still good to fix
it.
The real issue here is the code handling specifically the `min_value` literals. While I128_OVERFLOW
has the expected value (0x8000_..._0000), match using this value as a pattern is handled
incorrectly by the stage1 compiler (it seems to be handled correctly, by the stage2 compiler). So
what we do here is extract this pattern into an explicit `==` until the next snapshot.
Fixes#38987
fix function arguments in constant promotion
we can't create the target block until *after* we promote the arguments - otherwise the arguments will be promoted into the target block. oops.
Fixes#38985.
This is a regression introduced in the beta-nominated #38833, so beta-nominating this one too (sorry @brson).
r? @eddyb
we can't create the target block until *after* we promote the arguments
- otherwise the arguments will be promoted into the target block. oops.
Fixes#38985.
* 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
Remove destructor-related restrictions from unions
They don't have drop glue.
This doesn't fix the rvalue promotion issues when trying to do things like `static FOO: NoDrop<Bar> = NoDrop {inner: Bar}`. I'm not sure if we should fix that.
