This commits adds an associated type to the `FromStr` trait representing an
error payload for parses which do not succeed. The previous return value,
`Option<Self>` did not allow for this form of payload. After the associated type
was added, the following attributes were applied:
* `FromStr` is now stable
* `FromStr::Err` is now stable
* `FromStr::from_str` is now stable
* `StrExt::parse` is now stable
* `FromStr for bool` is now stable
* `FromStr for $float` is now stable
* `FromStr for $integral` is now stable
* Errors returned from stable `FromStr` implementations are stable
* Errors implement `Display` and `Error` (both impl blocks being `#[stable]`)
Closes#15138
Fixes#10302
I really am not sure I'm doing this right, so here goes nothing...
Also testing this isn't easy. I don't have any other *nix boxes besides a Linux one.
Test code:
```rust
use std::thread;
use std::io::timer::sleep;
use std::time::duration::Duration;
fn make_thread<'a>(i: i64) -> thread::JoinGuard<'a, ()>
{
thread::Builder::new().name(format!("MyThread{}", i).to_string()).scoped(move ||
{
println!("Start: {}", i);
sleep(Duration::seconds(i));
println!("End: {}", i);
})
}
fn main()
{
let mut guards = vec![make_thread(3)];
for i in 4i64..16
{
guards.push(make_thread(i));
}
}
```
GDB output on my machine:
```
(gdb) info threads
Id Target Id Frame
15 Thread 0x7fdfbb35f700 (LWP 23575) "MyThread3" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
14 Thread 0x7fdfba7ff700 (LWP 23576) "MyThread4" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
13 Thread 0x7fdfba5fe700 (LWP 23577) "MyThread5" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
12 Thread 0x7fdfba3fd700 (LWP 23578) "MyThread6" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
11 Thread 0x7fdfb8dfe700 (LWP 23580) "MyThread4" 0x00007fdfbb746193 in select () from /usr/lib/libc.so.6
10 Thread 0x7fdfb8fff700 (LWP 23579) "MyThread7" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
9 Thread 0x7fdfb8bfd700 (LWP 23581) "MyThread8" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
8 Thread 0x7fdfb3fff700 (LWP 23582) "MyThread9" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
7 Thread 0x7fdfb3dfe700 (LWP 23583) "MyThread10" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
6 Thread 0x7fdfb3bfd700 (LWP 23584) "MyThread11" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
5 Thread 0x7fdfb2bff700 (LWP 23585) "MyThread12" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
4 Thread 0x7fdfb29fe700 (LWP 23586) "MyThread13" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
3 Thread 0x7fdfb27fd700 (LWP 23587) "MyThread14" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
2 Thread 0x7fdfb1bff700 (LWP 23588) "MyThread15" 0x00007fdfbbe35a8d in nanosleep () from /usr/lib/libpthread.so.0
* 1 Thread 0x7fdfbc411800 (LWP 23574) "threads" 0x00007fdfbbe2e505 in pthread_join () from /usr/lib/libpthread.so.0
```
(I'm not sure why one of the threads is duplicated, but it does that without my patch too...)
The usecase is that functions made visible to systems outside of the
rust ecosystem require the symbol to be visible.
This adds a lint for functions that are not exported, but also not mangled.
It has some gotchas:
[ ]: There is fallout in core that needs taking care of
[ ]: I'm not convinced the error message is correct
[ ]: It has no tests
~~However, there's an underlying issue which I'd like feedback on- which is that my belief that that non-pub functions would not have their symbols exported, however that seems not to be the case in the first case that this lint turned up in rustc (`rust_fail`), which intuition suggests has been working.~~
This seems to be a separate bug in rust, wherein the symbols are exported in binaries, but not in rlibs or dylibs. This lint would catch that case.
As per [RFC #235][rfc], you can now do:
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0235-collections-conventions.md#intoiterator-and-iterable
``` rust
let mut v = vec![1];
// iterate over immutable references
for x in &v {
assert_eq!(x, &1);
}
// iterate over mutable references
for x in &mut v {
assert_eq!(x, &mut 1);
}
// iterate over values, this consumes `v`
for x in v {
assert_eq!(x, 1);
}
```
[breaking-change]s
For loops now "consume" (move) the iterator, this breaks iterating over mutable references to iterators, and also breaks multiple iterations over the same iterator:
``` rust
fn foo(mut it: &mut Iter) { // `Iter` implements `Iterator`
for x in it { .. } //~ error: `&mut Iter` doesn't implement Iterator
}
fn bar() {
for x in it { .. } //~ note: `it` moved here
for x in it { .. } //~ error: `it` has been moved
}
```
Both cases can be fixed using the `by_ref()` adapter to create an iterator from the mutable reference:
``` rust
fn foo(mut it: &mut Iter) {
for x in it.by_ref() { .. }
}
fn bar() {
for x in it.by_ref() { .. }
for x in it { .. }
}
```
This PR also makes iterator non-implicitly copyable, as this was source of subtle bugs in the libraries. You can still use `clone()` to explictly copy the iterator.
Finally, since the for loops are implemented in the frontend and use global paths to `IntoIterator`, `Iterator` and `Option` variants, users of the `core` crate will have to use add an `std` module to the root of their crate to be able to use for loops:
``` rust
#![no_std]
extern crate core;
fn main() {
for x in 0..10 {}
}
#[doc(hidden)]
mod std {
// these imports are needed to use for-loops
pub use core::iter;
pub use core::option;
}
```
---
r? @nikomatsakis @aturon
cc #18424closes#18045
The usecase is that functions made visible to systems outside of the
rust ecosystem require the symbol to be visible.
This adds a lint for functions that are not exported, but also not mangled.
It has some gotchas:
[ ]: There is fallout in core that needs taking care of
[ ]: I'm not convinced the error message is correct
[ ]: It has no tests
~~However, there's an underlying issue which I'd like feedback on- which is that my belief that that non-pub functions would not have their symbols exported, however that seems not to be the case in the first case that this lint turned up in rustc (`rust_fail`), which intuition suggests has been working.~~
This seems to be a separate bug in rust, wherein the symbols are exported in binaries, but not in rlibs or dylibs. This lint would catch that case.
This commit performs a final stabilization pass over the std::fmt module,
marking all necessary APIs as stable. One of the more interesting aspects of
this module is that it exposes a good deal of its runtime representation to the
outside world in order for `format_args!` to be able to construct the format
strings. Instead of hacking the compiler to assume that these items are stable,
this commit instead lays out a story for the stabilization and evolution of
these APIs.
There are three primary details used by the `format_args!` macro:
1. `Arguments` - an opaque package of a "compiled format string". This structure
is passed around and the `write` function is the source of truth for
transforming a compiled format string into a string at runtime. This must be
able to be constructed in stable code.
2. `Argument` - an opaque structure representing an argument to a format string.
This is *almost* a trait object as it's just a pointer/function pair, but due
to the function originating from one of many traits, it's not actually a
trait object. Like `Arguments`, this must be constructed from stable code.
3. `fmt::rt` - this module contains the runtime type definitions primarily for
the `rt::Argument` structure. Whenever an argument is formatted with
nonstandard flags, a corresponding `rt::Argument` is generated describing how
the argument is being formatted. This can be used to construct an
`Arguments`.
The primary interface to `std::fmt` is the `Arguments` structure, and as such
this type name is stabilize as-is today. It is expected for libraries to pass
around an `Arguments` structure to represent a pending formatted computation.
The remaining portions are largely "cruft" which would rather not be stabilized,
but due to the stability checks they must be. As a result, almost all pieces
have been renamed to represent that they are "version 1" of the formatting
representation. The theory is that at a later date if we change the
representation of these types we can add new definitions called "version 2" and
corresponding constructors for `Arguments`.
One of the other remaining large questions about the fmt module were how the
pending I/O reform would affect the signatures of methods in the module. Due to
[RFC 526][rfc], however, the writers of fmt are now incompatible with the
writers of io, so this question has largely been solved. As a result the
interfaces are largely stabilized as-is today.
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0526-fmt-text-writer.md
Specifically, the following changes were made:
* The contents of `fmt::rt` were all moved under `fmt::rt::v1`
* `fmt::rt` is stable
* `fmt::rt::v1` is stable
* `Error` is stable
* `Writer` is stable
* `Writer::write_str` is stable
* `Writer::write_fmt` is stable
* `Formatter` is stable
* `Argument` has been renamed to `ArgumentV1` and is stable
* `ArgumentV1::new` is stable
* `ArgumentV1::from_uint` is stable
* `Arguments::new_v1` is stable (renamed from `new`)
* `Arguments::new_v1_formatted` is stable (renamed from `with_placeholders`)
* All formatting traits are now stable, as well as the `fmt` method.
* `fmt::write` is stable
* `fmt::format` is stable
* `Formatter::pad_integral` is stable
* `Formatter::pad` is stable
* `Formatter::write_str` is stable
* `Formatter::write_fmt` is stable
* Some assorted top level items which were only used by `format_args!` were
removed in favor of static functions on `ArgumentV1` as well.
* The formatting-flag-accessing methods remain unstable
Within the contents of the `fmt::rt::v1` module, the following actions were
taken:
* Reexports of all enum variants were removed
* All prefixes on enum variants were removed
* A few miscellaneous enum variants were renamed
* Otherwise all structs, fields, and variants were marked stable.
In addition to these actions in the `std::fmt` module, many implementations of
`Show` and `String` were stabilized as well.
In some other modules:
* `ToString` is now stable
* `ToString::to_string` is now stable
* `Vec` no longer implements `fmt::Writer` (this has moved to `String`)
This is a breaking change due to all of the changes to the `fmt::rt` module, but
this likely will not have much impact on existing programs.
Closes#20661
[breaking-change]
This commits adds an associated type to the `FromStr` trait representing an
error payload for parses which do not succeed. The previous return value,
`Option<Self>` did not allow for this form of payload. After the associated type
was added, the following attributes were applied:
* `FromStr` is now stable
* `FromStr::Err` is now stable
* `FromStr::from_str` is now stable
* `StrExt::parse` is now stable
* `FromStr for bool` is now stable
* `FromStr for $float` is now stable
* `FromStr for $integral` is now stable
* Errors returned from stable `FromStr` implementations are stable
* Errors implement `Display` and `Error` (both impl blocks being `#[stable]`)
Closes#15138
Coercions will now attempt to autoderef as needed before reborrowing.
This includes overloaded `Deref`, e.g. `&Rc<T>` coerces to `&T`, and
`DerefMut`, e.g. `&mut Vec<T>` coerces to `&mut [T]` (in addition to `&[T]`).
Closes#21432.
