This change makes the compiler no longer infer whether types (structures
and enumerations) implement the `Copy` trait (and thus are implicitly
copyable). Rather, you must implement `Copy` yourself via `impl Copy for
MyType {}`.
A new warning has been added, `missing_copy_implementations`, to warn
you if a non-generic public type has been added that could have
implemented `Copy` but didn't.
For convenience, you may *temporarily* opt out of this behavior by using
`#![feature(opt_out_copy)]`. Note though that this feature gate will never be
accepted and will be removed by the time that 1.0 is released, so you should
transition your code away from using it.
This breaks code like:
#[deriving(Show)]
struct Point2D {
x: int,
y: int,
}
fn main() {
let mypoint = Point2D {
x: 1,
y: 1,
};
let otherpoint = mypoint;
println!("{}{}", mypoint, otherpoint);
}
Change this code to:
#[deriving(Show)]
struct Point2D {
x: int,
y: int,
}
impl Copy for Point2D {}
fn main() {
let mypoint = Point2D {
x: 1,
y: 1,
};
let otherpoint = mypoint;
println!("{}{}", mypoint, otherpoint);
}
This is the backwards-incompatible part of #13231.
Part of RFC #3.
[breaking-change]
Now that we have an overloaded comparison (`==`) operator, and that `Vec`/`String` deref to `[T]`/`str` on method calls, many `as_slice()`/`as_mut_slice()`/`to_string()` calls have become redundant. This patch removes them. These were the most common patterns:
- `assert_eq(test_output.as_slice(), "ground truth")` -> `assert_eq(test_output, "ground truth")`
- `assert_eq(test_output, "ground truth".to_string())` -> `assert_eq(test_output, "ground truth")`
- `vec.as_mut_slice().sort()` -> `vec.sort()`
- `vec.as_slice().slice(from, to)` -> `vec.slice(from_to)`
---
Note that e.g. `a_string.push_str(b_string.as_slice())` has been left untouched in this PR, since we first need to settle down whether we want to favor the `&*b_string` or the `b_string[]` notation.
This is rebased on top of #19167
cc @alexcrichton @aturon
In regards to:
https://github.com/rust-lang/rust/issues/19253#issuecomment-64836729
This commit:
* Changes the #deriving code so that it generates code that utilizes fewer
reexports (in particur Option::\*, Result::\*, and Ordering::\*), which is necessary to
remove those reexports in the future
* Changes other areas of the codebase so that fewer reexports are utilized
Previously, `BufWriter::write` would just return an `std::io::OtherIoError` if someone attempted to write past the end of the wrapped buffer. This pull request changes the error to support partial writes and return a `std::io::ShortWrite`, or an `io::io::EndOfFile` if it's been fully exhausted.
I've also optimized away a bounds check inside `BufWriter::write`, which should help shave off some nanoseconds in an inner loops.
In regards to:
https://github.com/rust-lang/rust/issues/19253#issuecomment-64836729
This commit:
* Changes the #deriving code so that it generates code that utilizes fewer
reexports (in particur Option::* and Result::*), which is necessary to
remove those reexports in the future
* Changes other areas of the codebase so that fewer reexports are utilized
After the library successfully called `fork(2)`, the child does several
setup works such as setting UID, GID and current directory before it
calls `exec(2)`. When those setup works failed, the child exits but the
parent didn't call `waitpid(2)` and left it as a zombie.
This patch also add several sanity checks. They shouldn't make any
noticeable impact to runtime performance.
The new test case in `libstd/io/process.rs` calls the ps command to check
if the new code can really reap a zombie.
The output of `ps -A -o pid,sid,command` should look like this:
```
PID SID COMMAND
1 1 /sbin/init
2 0 [kthreadd]
3 0 [ksoftirqd/0]
...
12562 9237 ./spawn-failure
12563 9237 [spawn-failure] <defunct>
12564 9237 [spawn-failure] <defunct>
...
12592 9237 [spawn-failure] <defunct>
12593 9237 ps -A -o pid,sid,command
12884 12884 /bin/zsh
12922 12922 /bin/zsh
...
```
where `./spawn-failure` is my test program which intentionally leaves many
zombies. Filtering the output with the "SID" (session ID) column is
a quick way to tell if a process (zombie) was spawned by my own test
program. Then the number of "defunct" lines is the number of zombie
children.
io::stdin returns a new `BufferedReader` each time it's called, which
results in some very confusing behavior with disappearing output. It now
returns a `StdinReader`, which wraps a global singleton
`Arc<Mutex<BufferedReader<StdReader>>`. `Reader` is implemented directly
on `StdinReader`. However, `Buffer` is not, as the `fill_buf` method is
fundamentaly un-thread safe. A `lock` method is defined on `StdinReader`
which returns a smart pointer wrapping the underlying `BufferedReader`
while guaranteeing mutual exclusion.
Code that treats the return value of io::stdin as implementing `Buffer`
will break. Add a call to `lock`:
```rust
io::stdin().read_line();
// =>
io::stdin().lock().read_line();
```
Closes#14434
[breaking-change]
This commit is a reimplementation of `std::sync` to be based on the
system-provided primitives wherever possible. The previous implementation was
fundamentally built on top of channels, and as part of the runtime reform it has
become clear that this is not the level of abstraction that the standard level
should be providing. This rewrite aims to provide as thin of a shim as possible
on top of the system primitives in order to make them safe.
The overall interface of the `std::sync` module has in general not changed, but
there are a few important distinctions, highlighted below:
* The condition variable type, `Condvar`, has been separated out of a `Mutex`.
A condition variable is now an entirely separate type. This separation
benefits users who only use one mutex, and provides a clearer distinction of
who's responsible for managing condition variables (the application).
* All of `Condvar`, `Mutex`, and `RWLock` are now directly built on top of
system primitives rather than using a custom implementation. The `Once`,
`Barrier`, and `Semaphore` types are still built upon these abstractions of
the system primitives.
* The `Condvar`, `Mutex`, and `RWLock` types all have a new static type and
constant initializer corresponding to them. These are provided primarily for C
FFI interoperation, but are often useful to otherwise simply have a global
lock. The types, however, will leak memory unless `destroy()` is called on
them, which is clearly documented.
* The fundamental architecture of this design is to provide two separate layers.
The first layer is that exposed by `sys_common` which is a cross-platform
bare-metal abstraction of the system synchronization primitives. No attempt is
made at making this layer safe, and it is quite unsafe to use! It is currently
not exported as part of the API of the standard library, but the stabilization
of the `sys` module will ensure that these will be exposed in time. The
purpose of this layer is to provide the core cross-platform abstractions if
necessary to implementors.
The second layer is the layer provided by `std::sync` which is intended to be
the thinnest possible layer on top of `sys_common` which is entirely safe to
use. There are a few concerns which need to be addressed when making these
system primitives safe:
* Once used, the OS primitives can never be **moved**. This means that they
essentially need to have a stable address. The static primitives use
`&'static self` to enforce this, and the non-static primitives all use a
`Box` to provide this guarantee.
* Poisoning is leveraged to ensure that invalid data is not accessible from
other tasks after one has panicked.
In addition to these overall blanket safety limitations, each primitive has a
few restrictions of its own:
* Mutexes and rwlocks can only be unlocked from the same thread that they
were locked by. This is achieved through RAII lock guards which cannot be
sent across threads.
* Mutexes and rwlocks can only be unlocked if they were previously locked.
This is achieved by not exposing an unlocking method.
* A condition variable can only be waited on with a locked mutex. This is
achieved by requiring a `MutexGuard` in the `wait()` method.
* A condition variable cannot be used concurrently with more than one mutex.
This is guaranteed by dynamically binding a condition variable to
precisely one mutex for its entire lifecycle. This restriction may be able
to be relaxed in the future (a mutex is unbound when no threads are
waiting on the condvar), but for now it is sufficient to guarantee safety.
* Condvars support timeouts for their blocking operations. The
implementation for these operations is provided by the system.
Due to the modification of the `Condvar` API, removal of the `std::sync::mutex`
API, and reimplementation, this is a breaking change. Most code should be fairly
easy to port using the examples in the documentation of these primitives.
[breaking-change]
Closes#17094Closes#18003
This commit is a reimplementation of `std::sync` to be based on the
system-provided primitives wherever possible. The previous implementation was
fundamentally built on top of channels, and as part of the runtime reform it has
become clear that this is not the level of abstraction that the standard level
should be providing. This rewrite aims to provide as thin of a shim as possible
on top of the system primitives in order to make them safe.
The overall interface of the `std::sync` module has in general not changed, but
there are a few important distinctions, highlighted below:
* The condition variable type, `Condvar`, has been separated out of a `Mutex`.
A condition variable is now an entirely separate type. This separation
benefits users who only use one mutex, and provides a clearer distinction of
who's responsible for managing condition variables (the application).
* All of `Condvar`, `Mutex`, and `RWLock` are now directly built on top of
system primitives rather than using a custom implementation. The `Once`,
`Barrier`, and `Semaphore` types are still built upon these abstractions of
the system primitives.
* The `Condvar`, `Mutex`, and `RWLock` types all have a new static type and
constant initializer corresponding to them. These are provided primarily for C
FFI interoperation, but are often useful to otherwise simply have a global
lock. The types, however, will leak memory unless `destroy()` is called on
them, which is clearly documented.
* The `Condvar` implementation for an `RWLock` write lock has been removed. This
may be added back in the future with a userspace implementation, but this
commit is focused on exposing the system primitives first.
* The fundamental architecture of this design is to provide two separate layers.
The first layer is that exposed by `sys_common` which is a cross-platform
bare-metal abstraction of the system synchronization primitives. No attempt is
made at making this layer safe, and it is quite unsafe to use! It is currently
not exported as part of the API of the standard library, but the stabilization
of the `sys` module will ensure that these will be exposed in time. The
purpose of this layer is to provide the core cross-platform abstractions if
necessary to implementors.
The second layer is the layer provided by `std::sync` which is intended to be
the thinnest possible layer on top of `sys_common` which is entirely safe to
use. There are a few concerns which need to be addressed when making these
system primitives safe:
* Once used, the OS primitives can never be **moved**. This means that they
essentially need to have a stable address. The static primitives use
`&'static self` to enforce this, and the non-static primitives all use a
`Box` to provide this guarantee.
* Poisoning is leveraged to ensure that invalid data is not accessible from
other tasks after one has panicked.
In addition to these overall blanket safety limitations, each primitive has a
few restrictions of its own:
* Mutexes and rwlocks can only be unlocked from the same thread that they
were locked by. This is achieved through RAII lock guards which cannot be
sent across threads.
* Mutexes and rwlocks can only be unlocked if they were previously locked.
This is achieved by not exposing an unlocking method.
* A condition variable can only be waited on with a locked mutex. This is
achieved by requiring a `MutexGuard` in the `wait()` method.
* A condition variable cannot be used concurrently with more than one mutex.
This is guaranteed by dynamically binding a condition variable to
precisely one mutex for its entire lifecycle. This restriction may be able
to be relaxed in the future (a mutex is unbound when no threads are
waiting on the condvar), but for now it is sufficient to guarantee safety.
* Condvars now support timeouts for their blocking operations. The
implementation for these operations is provided by the system.
Due to the modification of the `Condvar` API, removal of the `std::sync::mutex`
API, and reimplementation, this is a breaking change. Most code should be fairly
easy to port using the examples in the documentation of these primitives.
[breaking-change]
Closes#17094Closes#18003
This may have inadvertently switched during the runtime overhaul, so this
switches TcpListener back to using sockets instead of file descriptors. This
also renames a bunch of variables called `fd` to `socket` to clearly show that
it's not a file descriptor.
Closes#19333
After the library successfully called fork(2), the child does several
setup works such as setting UID, GID and current directory before it
calls exec(2). When those setup works failed, the child exits but the
parent didn't call waitpid(2) and left it as a zombie.
This patch also add several sanity checks. They shouldn't make any
noticeable impact to runtime performance.
The new test case run-pass/wait-forked-but-failed-child.rs calls the ps
command to check if the new code can really reap a zombie. When
I intentionally create many zombies with my test program
./spawn-failure, The output of "ps -A -o pid,sid,command" should look
like this:
PID SID COMMAND
1 1 /sbin/init
2 0 [kthreadd]
3 0 [ksoftirqd/0]
...
12562 9237 ./spawn-failure
12563 9237 [spawn-failure] <defunct>
12564 9237 [spawn-failure] <defunct>
...
12592 9237 [spawn-failure] <defunct>
12593 9237 ps -A -o pid,sid,command
12884 12884 /bin/zsh
12922 12922 /bin/zsh
...
Filtering the output with the "SID" (session ID) column is a quick way
to tell if a process (zombie) was spawned by my own test program. Then
the number of "defunct" lines is the number of zombie children.
Signed-off-by: NODA, Kai <nodakai@gmail.com>
On *BSD systems, we can `open(2)` a directory and directly `read(2)` from it due to an old tradition. We should avoid doing so by explicitly calling `fstat(2)` to check the type of the opened file.
Opening a directory as a module file can't always be avoided. Even when there's no "path" attribute trick involved, there can always be a *directory* named `my_module.rs`.
Incidentally, remove unnecessary mutability of `&self` from `io::fs::File::stat()`.
This continues the work @thestinger started in #18885 (which hasn't landed yet, so wait for that to land before landing this one). Instead of adding more methods to `BufReader`, this just allows a `&[u8]` to be used directly as a `Reader`. It also adds an impl of `Writer` for `&mut [u8]`.
Comparison traits have gained an `Rhs` input parameter that defaults to `Self`. And now the comparison operators can be overloaded to work between different types. In particular, this PR allows the following operations (and their commutative versions):
- `&str` == `String` == `CowString`
- `&[A]` == `&mut [B]` == `Vec<C>` == `CowVec<D>` == `[E, ..N]` (for `N` up to 32)
- `&mut A` == `&B` (for `Sized` `A` and `B`)
Where `A`, `B`, `C`, `D`, `E` may be different types that implement `PartialEq`. For example, these comparisons are now valid: `string == "foo"`, and `vec_of_strings == ["Hello", "world"]`.
[breaking-change]s
Since the `==` may now work on different types, operations that relied on the old "same type restriction" to drive type inference, will need to be type annotated. These are the most common fallout cases:
- `some_vec == some_iter.collect()`: `collect` needs to be type annotated: `collect::<Vec<_>>()`
- `slice == &[a, b, c]`: RHS doesn't get coerced to an slice, use an array instead `[a, b, c]`
- `lhs == []`: Change expression to `lhs.is_empty()`
- `lhs == some_generic_function()`: Type annotate the RHS as necessary
cc #19148
r? @aturon
io::stdin returns a new `BufferedReader` each time it's called, which
results in some very confusing behavior with disappearing output. It now
returns a `StdinReader`, which wraps a global singleton
`Arc<Mutex<BufferedReader<StdReader>>`. `Reader` is implemented directly
on `StdinReader`. However, `Buffer` is not, as the `fill_buf` method is
fundamentaly un-thread safe. A `lock` method is defined on `StdinReader`
which returns a smart pointer wrapping the underlying `BufferedReader`
while guaranteeing mutual exclusion.
Code that treats the return value of io::stdin as implementing `Buffer`
will break. Add a call to `lock`:
```rust
io::stdin().lines()
// =>
io::stdin().lock().lines()
```
Closes#14434
[breaking-change]
On *BSD systems, we can open(2) a directory and directly read(2) from
it due to an old tradition. We should avoid doing so by explicitly
calling fstat(2) to check the type of the opened file.
Opening a directory as a module file can't always be avoided.
Even when there's no "path" attribute trick involved, there can always
be a *directory* named "my_module.rs".
Fix#12460
Signed-off-by: NODA, Kai <nodakai@gmail.com>
The previous code was giving an incorrect result (not x/3).
Also, this function does not work with signed integers. It now accepts `u32` instead of `i32`.
