Fixes https://github.com/rust-lang/rust/issues/26408
Example output when using `Result::unwrap`:
```
thread '<main>' panicked at 'called `Result::unwrap()` on an `Err` value: Error { repr: Os { code: 2, message: "The system cannot find the file specified.\r\n" } }', src/libcore\result.rs:731
```
This could technically be considered a breaking change for any code that depends on the format of the `Debug` output for `io::Error` but I sincerely hope nobody wrote code like that.
This commit shards the all-encompassing `core`, `std_misc`, `collections`, and `alloc` features into finer-grained components that are much more easily opted into and tracked. This reflects the effort to push forward current unstable APIs to either stabilization or removal. Keeping track of unstable features on a much more fine-grained basis will enable the library subteam to quickly analyze a feature and help prioritize internally about what APIs should be stabilized.
A few assorted APIs were deprecated along the way, but otherwise this change is just changing the feature name associated with each API. Soon we will have a dashboard for keeping track of all the unstable APIs in the standard library, and I'll also start making issues for each unstable API after performing a first-pass for stabilization.
The `thread::scoped` function will never be stabilized as-is and the API will
likely change significantly if it does, so this function is deprecated for
removal.
This function follows the well-established "constructor" pattern and the
initialization constant will likely be deprecated in favor of it once `const_fn`
is stabilized.
This commit shards the broad `core` feature of the libcore library into finer
grained features. This split groups together similar APIs and enables tracking
each API separately, giving a better sense of where each feature is within the
stabilization process.
A few minor APIs were deprecated along the way:
* Iterator::reverse_in_place
* marker::NoCopy
Currently the compiler has no knowledge of `#[thread_local]` which forces users
to take on two burdens of unsafety:
* The lifetime of the borrow of a `#[thread_local]` static is **not** `'static`
* Types in `static`s are required to be `Sync`
The thread-local modules mostly curb these facets of unsafety by only allowing
very limited scopes of borrows as well as allowing all types to be stored in a
thread-local key (regardless of whether they are `Sync`) through an `unsafe
impl`.
Unfortunately these measures have the consequence of being able to take the
address of the key itself and send it to another thread, allowing the same key
to be accessed from two different threads. This is clearly unsafe, and this
commit fixes this problem with the same trick used by `LocalKey`, which is to
have an indirect function call to find the address of the *current thread's*
thread local. This way the address of thread local keys can safely be sent among
threads as their lifetime truly is `'static`.
This commit will reduce the performance of cross-crate scoped thread locals as
it now requires an indirect function call, but this can likely be overcome in a
future commit.
Closes#25894
Closes#25977
The various `stdfoo_raw` methods in std::io now return `io::Result`s,
since they may not exist on Windows. They will always return `Ok` on
Unix-like platforms.
[breaking-change]
Closes#25977
The various `stdfoo_raw` methods in std::io now return `io::Result`s,
since they may not exist on Windows. They will always return `Ok` on
Unix-like platforms.
[breaking-change]
This commit stabilizes the following APIs, slating them all to be cherry-picked
into the 1.1 release.
* fs::FileType (and transitively the derived trait implementations)
* fs::Metadata::file_type
* fs::FileType::is_dir
* fs::FileType::is_file
* fs::FileType::is_symlink
* fs::DirEntry::metadata
* fs::DirEntry::file_type
* fs::DirEntry::file_name
* fs::set_permissions
* fs::symlink_metadata
* os::raw::{self, *}
* os::{android, bitrig, linux, ...}::raw::{self, *}
* os::{android, bitrig, linux, ...}::fs::MetadataExt
* os::{android, bitrig, linux, ...}::fs::MetadataExt::as_raw_stat
* os::unix::fs::PermissionsExt
* os::unix::fs::PermissionsExt::mode
* os::unix::fs::PermissionsExt::set_mode
* os::unix::fs::PermissionsExt::from_mode
* os::unix::fs::OpenOptionsExt
* os::unix::fs::OpenOptionsExt::mode
* os::unix::fs::DirEntryExt
* os::unix::fs::DirEntryExt::ino
* os::windows::fs::MetadataExt
* os::windows::fs::MetadataExt::file_attributes
* os::windows::fs::MetadataExt::creation_time
* os::windows::fs::MetadataExt::last_access_time
* os::windows::fs::MetadataExt::last_write_time
* os::windows::fs::MetadataExt::file_size
The `os::unix::fs::Metadata` structure was also removed entirely, moving all of
its associated methods into the `os::unix::fs::MetadataExt` trait instead. The
methods are all marked as `#[stable]` still.
As some minor cleanup, some deprecated and unstable fs apis were also removed:
* File::path
* Metadata::accessed
* Metadata::modified
Features that were explicitly left unstable include:
* fs::WalkDir - the semantics of this were not considered in the recent fs
expansion RFC.
* fs::DirBuilder - it's still not 100% clear if the naming is right here and if
the set of functionality exposed is appropriate.
* fs::canonicalize - the implementation on Windows here is specifically in
question as it always returns a verbatim path. Additionally the Unix
implementation is susceptible to buffer overflows on long paths unfortunately.
* fs::PathExt - as this is just a convenience trait, it is not stabilized at
this time.
* fs::set_file_times - this funciton is still waiting on a time abstraction.
* Slate these features to be stable in 1.2 instead of 1.1 (not being backported)
* Have the `FromRawFd` implementations follow the contract of the `FromRawFd`
trait by taking ownership of the primitive specified.
* Refactor the implementations slightly to remove the `unreachable!` blocks as
well as separating the stdio representation of `std::process` from
`std::sys::process`.
cc #25494
As far as I was able to determine, it's currently *impossible* to allocate a C NUL-terminated string in Rust and then return it to C (transferring ownership), without leaking memory. There is support for passing the string to C (borrowing).
To complicate matters, it's not possible for the C code to just call `free` on the allocated string, due to the different allocators in use.
`CString` has no way to recreate itself from a pointer. This commit adds one. This is complicated a bit because Rust `Vec`s want the pointer, size, and capacity.
To deal with that, another method to shrink and "leak" the `CString` to a `char *` is also provided.
We can then use `strlen` to determine the length of the string, which must match the capacity.
**TODO**
- [x] Improve documentation
- [x] Add stability markers
- [x] Convert to `Box<[u8]>`
### Example code
With this example code:
```rust
#![feature(libc)]
#![feature(cstr_to_str)]
#![feature(c_str_memory)]
extern crate libc;
use std::ffi::{CStr,CString};
#[no_mangle]
pub extern fn reverse(s: *const libc::c_char) -> *const libc::c_char {
let s = unsafe { CStr::from_ptr(s) };
let s2 = s.to_str().unwrap();
let s3: String = s2.chars().rev().collect();
let s4 = CString::new(s3).unwrap();
s4.into_ptr()
}
#[no_mangle]
pub extern fn cleanup(s: *const libc::c_char) {
unsafe { CString::from_ptr(s) };
}
```
Compiled using `rustc --crate-type dylib str.rs`, I was able to link against it from C (`gcc -L. -l str str.c -o str`):
```c
#include <stdio.h>
extern char *reverse(char *);
extern void cleanup(char *);
int main() {
char *s = reverse("Hello, world!");
printf("%s\n", s);
cleanup(s);
}
```
As well as dynamically link via Ruby:
```ruby
require 'fiddle'
require 'fiddle/import'
module LibSum
extend Fiddle::Importer
dlload './libstr.dylib'
extern 'char* reverse(char *)'
extern 'void cleanup(char *)'
end
s = LibSum.reverse("hello, world!")
puts s
LibSum.cleanup(s)
```
* Slate these features to be stable in 1.2 instead of 1.1 (not being backported)
* Have the `FromRawFd` implementations follow the contract of the `FromRawFd`
trait by taking ownership of the primitive specified.
* Refactor the implementations slightly to remove the `unreachable!` blocks as
well as separating the stdio representation of `std::process` from
`std::sys::process`.
This commit stabilizes the following APIs, slating them all to be cherry-picked
into the 1.1 release.
* fs::FileType (and transitively the derived trait implementations)
* fs::Metadata::file_type
* fs::FileType::is_dir
* fs::FileType::is_file
* fs::FileType::is_symlink
* fs::DirEntry::metadata
* fs::DirEntry::file_type
* fs::DirEntry::file_name
* fs::set_permissions
* fs::symlink_metadata
* os::raw::{self, *}
* os::{android, bitrig, linux, ...}::raw::{self, *}
* os::{android, bitrig, linux, ...}::fs::MetadataExt
* os::{android, bitrig, linux, ...}::fs::MetadataExt::as_raw_stat
* os::unix::fs::PermissionsExt
* os::unix::fs::PermissionsExt::mode
* os::unix::fs::PermissionsExt::set_mode
* os::unix::fs::PermissionsExt::from_mode
* os::unix::fs::OpenOptionsExt
* os::unix::fs::OpenOptionsExt::mode
* os::unix::fs::DirEntryExt
* os::unix::fs::DirEntryExt::ino
* os::windows::fs::MetadataExt
* os::windows::fs::MetadataExt::file_attributes
* os::windows::fs::MetadataExt::creation_time
* os::windows::fs::MetadataExt::last_access_time
* os::windows::fs::MetadataExt::last_write_time
* os::windows::fs::MetadataExt::file_size
The `os::unix::fs::Metadata` structure was also removed entirely, moving all of
its associated methods into the `os::unix::fs::MetadataExt` trait instead. The
methods are all marked as `#[stable]` still.
As some minor cleanup, some deprecated and unstable fs apis were also removed:
* File::path
* Metadata::accessed
* Metadata::modified
Features that were explicitly left unstable include:
* fs::WalkDir - the semantics of this were not considered in the recent fs
expansion RFC.
* fs::DirBuilder - it's still not 100% clear if the naming is right here and if
the set of functionality exposed is appropriate.
* fs::canonicalize - the implementation on Windows here is specifically in
question as it always returns a verbatim path. Additionally the Unix
implementation is susceptible to buffer overflows on long paths unfortunately.
* fs::PathExt - as this is just a convenience trait, it is not stabilized at
this time.
* fs::set_file_times - this funciton is still waiting on a time abstraction.
With the latter is provided by the `From` conversion trait, the former is now completely redundant. Their code is identical. Let’s deprecate now and plan to remove in the next cycle. (It’s `#[unstable]`.)
r? @alexcrichton
CC @nagisa
