f9fc49c06e
This change is an implementation of [RFC 69][rfc] which adds a third kind of
global to the language, `const`. This global is most similar to what the old
`static` was, and if you're unsure about what to use then you should use a
`const`.
The semantics of these three kinds of globals are:
* A `const` does not represent a memory location, but only a value. Constants
are translated as rvalues, which means that their values are directly inlined
at usage location (similar to a #define in C/C++). Constant values are, well,
constant, and can not be modified. Any "modification" is actually a
modification to a local value on the stack rather than the actual constant
itself.
Almost all values are allowed inside constants, whether they have interior
mutability or not. There are a few minor restrictions listed in the RFC, but
they should in general not come up too often.
* A `static` now always represents a memory location (unconditionally). Any
references to the same `static` are actually a reference to the same memory
location. Only values whose types ascribe to `Sync` are allowed in a `static`.
This restriction is in place because many threads may access a `static`
concurrently. Lifting this restriction (and allowing unsafe access) is a
future extension not implemented at this time.
* A `static mut` continues to always represent a memory location. All references
to a `static mut` continue to be `unsafe`.
This is a large breaking change, and many programs will need to be updated
accordingly. A summary of the breaking changes is:
* Statics may no longer be used in patterns. Statics now always represent a
memory location, which can sometimes be modified. To fix code, repurpose the
matched-on-`static` to a `const`.
static FOO: uint = 4;
match n {
FOO => { /* ... */ }
_ => { /* ... */ }
}
change this code to:
const FOO: uint = 4;
match n {
FOO => { /* ... */ }
_ => { /* ... */ }
}
* Statics may no longer refer to other statics by value. Due to statics being
able to change at runtime, allowing them to reference one another could
possibly lead to confusing semantics. If you are in this situation, use a
constant initializer instead. Note, however, that statics may reference other
statics by address, however.
* Statics may no longer be used in constant expressions, such as array lengths.
This is due to the same restrictions as listed above. Use a `const` instead.
[breaking-change]
Closes #17718
[rfc]: https://github.com/rust-lang/rfcs/pull/246
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| man | ||
| mk | ||
| src | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| .travis.yml | ||
| AUTHORS.txt | ||
| configure | ||
| CONTRIBUTING.md | ||
| COPYRIGHT | ||
| LICENSE-APACHE | ||
| LICENSE-MIT | ||
| Makefile.in | ||
| README.md | ||
| RELEASES.md | ||
The Rust Programming Language
This is a compiler for Rust, including standard libraries, tools and documentation.
Quick Start
- Download a binary installer for your platform.
- Read the guide.
- Enjoy!
Note: Windows users can read the detailed getting started notes on the wiki.
Building from Source
-
Make sure you have installed the dependencies:
g++4.7 orclang++3.xpython2.6 or later (but not 3.x)perl5.0 or later- GNU
make3.81 or later curlgit
-
Download and build Rust:
You can either download a tarball or build directly from the repo.
To build from the tarball do:
$ curl -O https://static.rust-lang.org/dist/rust-nightly.tar.gz $ tar -xzf rust-nightly.tar.gz $ cd rust-nightlyOr to build from the repo do:
$ git clone https://github.com/rust-lang/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, andrustdoc, the API-documentation tool. -
Read the guide.
-
Enjoy!
Building on Windows
To easily build on windows we can use MSYS2:
-
Grab the latest MSYS2 installer and go through the installer.
-
Now from the MSYS2 terminal we want to install the mingw64 toolchain and the other tools we need.
$ pacman -S mingw-w64-i686-toolchain $ pacman -S base-devel -
With that now start
mingw32_shell.batfrom where you installed MSYS2 (i.e.C:\msys). -
From there just navigate to where you have Rust's source code, configure and build it:
$ ./configure $ make && make install
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, 8, Server 2008 R2), x86 only
- Linux (2.6.18 or later, various distributions), x86 and x86-64
- OSX 10.7 (Lion) 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.
Getting help and getting involved
The Rust community congregates in a few places:
- StackOverflow - Get help here.
- /r/rust - General discussion.
- discuss.rust-lang.org - For development of the Rust language itself.
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.