cd8ee786f9
A mutable and immutable borrow place some restrictions on what you can
with the variable until the borrow ends. This commit attempts to convey
to the user what those restrictions are. Also, if the original borrow is
a mutable borrow, the error message has been changed (more specifically,
i. "cannot borrow `x` as immutable because it is also borrowed as
mutable" and ii. "cannot borrow `x` as mutable more than once" have
been changed to "cannot borrow `x` because it is already borrowed as
mutable").
In addition, this adds a (custom) span note to communicate where the
original borrow ends.
```rust
fn main() {
match true {
true => {
let mut x = 1;
let y = &x;
let z = &mut x;
}
false => ()
}
}
test.rs:6:21: 6:27 error: cannot borrow `x` as mutable because it is already borrowed as immutable
test.rs:6 let z = &mut x;
^~~~~~
test.rs:5:21: 5:23 note: previous borrow of `x` occurs here; the immutable borrow prevents subsequent moves or mutable borrows of `x` until the borrow ends
test.rs:5 let y = &x;
^~
test.rs:7:10: 7:10 note: previous borrow ends here
test.rs:3 true => {
test.rs:4 let mut x = 1;
test.rs:5 let y = &x;
test.rs:6 let z = &mut x;
test.rs:7 }
^
```
```rust
fn foo3(t0: &mut &mut int) {
let t1 = &mut *t0;
let p: &int = &**t0;
}
fn main() {}
test.rs:3:19: 3:24 error: cannot borrow `**t0` because it is already borrowed as mutable
test.rs:3 let p: &int = &**t0;
^~~~~
test.rs:2:14: 2:22 note: previous borrow of `**t0` as mutable occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of `**t0` until the borrow ends
test.rs:2 let t1 = &mut *t0;
^~~~~~~~
test.rs:4:2: 4:2 note: previous borrow ends here
test.rs:1 fn foo3(t0: &mut &mut int) {
test.rs:2 let t1 = &mut *t0;
test.rs:3 let p: &int = &**t0;
test.rs:4 }
^
```
For the "previous borrow ends here" note, if the span is too long (has too many lines), then only the first and last lines are printed, and the middle is replaced with dot dot dot:
```rust
fn foo3(t0: &mut &mut int) {
let t1 = &mut *t0;
let p: &int = &**t0;
}
fn main() {}
test.rs:3:19: 3:24 error: cannot borrow `**t0` because it is already borrowed as mutable
test.rs:3 let p: &int = &**t0;
^~~~~
test.rs:2:14: 2:22 note: previous borrow of `**t0` as mutable occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of `**t0` until the borrow ends
test.rs:2 let t1 = &mut *t0;
^~~~~~~~
test.rs:7:2: 7:2 note: previous borrow ends here
test.rs:1 fn foo3(t0: &mut &mut int) {
...
test.rs:7 }
^
```
(Sidenote: the `span_end_note` currently also has issue #11715)
|
||
|---|---|---|
| doc | ||
| man | ||
| mk | ||
| src | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| AUTHORS.txt | ||
| configure | ||
| CONTRIBUTING.md | ||
| COPYRIGHT | ||
| LICENSE-APACHE | ||
| LICENSE-MIT | ||
| Makefile.in | ||
| README.md | ||
| RELEASES.txt | ||
The Rust Programming Language
This is a compiler for Rust, including standard libraries, tools and documentation.
Quick Start
Windows
- Download and use the installer and MinGW.
- Read the tutorial.
- Enjoy!
Note: Windows users can read the detailed getting started notes on the wiki.
Linux / OS X
-
Make sure you have installed the dependencies:
g++4.4 orclang++3.xpython2.6 or later (but not 3.x)perl5.0 or later- GNU
make3.81 or later curl
-
Download and build Rust:
You can either download a tarball or build directly from the repo.
To build from the tarball do:
$ curl -O http://static.rust-lang.org/dist/rust-0.9.tar.gz $ tar -xzf rust-0.9.tar.gz $ cd rust-0.9Or to build from the repo do:
$ git clone https://github.com/mozilla/rust.git $ cd rustNow that you have Rust's source code, you can configure and build it:
$ ./configure $ make && make installNote: You may need to use
sudo make installif you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a--prefixargument toconfigure. Various other options are also supported, pass--helpfor more information on them.When complete,
make installwill place several programs into/usr/local/bin:rustc, the Rust compiler;rustdoc, the API-documentation tool, andrustpkg, the Rust package manager and build system. -
Read the tutorial.
-
Enjoy!
Notes
Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.
Snapshot binaries are currently built and tested on several platforms:
- Windows (7, Server 2008 R2), x86 only
- Linux (various distributions), x86 and x86-64
- OSX 10.6 ("Snow Leopard") or greater, x86 and x86-64
You may find that other platforms work, but these are our officially supported build environments that are most likely to work.
Rust currently needs about 1.5 GiB of RAM to build without swapping; if it hits swap, it will take a very long time to build.
There is a lot more documentation in the wiki.
License
Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.
See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.