9ca75619dc
Implement RFC 1210: impl specialization This PR implements [impl specialization](https://github.com/rust-lang/rfcs/pull/1210), carefully following the proposal laid out in the RFC. The implementation covers the bulk of the RFC. The remaining gaps I know of are: - no checking for lifetime-dependent specialization (a soundness hole); - no `default impl` yet; - no support for `default` with associated consts; I plan to cover these gaps in follow-up PRs, as per @nikomatsakis's preference. The basic strategy is to build up a *specialization graph* during coherence checking. Insertion into the graph locates the right place to put an impl in the specialization hierarchy; if there is no right place (due to partial overlap but no containment), you get an overlap error. Specialization is consulted when selecting an impl (of course), and the graph is consulted when propagating defaults down the specialization hierarchy. You might expect that the specialization graph would be used during selection -- i.e., when actually performing specialization. This is not done for two reasons: - It's merely an optimization: given a set of candidates that apply, we can determine the most specialized one by comparing them directly for specialization, rather than consulting the graph. Given that we also cache the results of selection, the benefit of this optimization is questionable. - To build the specialization graph in the first place, we need to use selection (because we need to determine whether one impl specializes another). Dealing with this reentrancy would require some additional mode switch for selection. Given that there seems to be no strong reason to use the graph anyway, we stick with a simpler approach in selection, and use the graph only for propagating default implementations. Trait impl selection can succeed even when multiple impls can apply, as long as they are part of the same specialization family. In that case, it returns a *single* impl on success -- this is the most specialized impl *known* to apply. However, if there are any inference variables in play, the returned impl may not be the actual impl we will use at trans time. Thus, we take special care to avoid projecting associated types unless either (1) the associated type does not use `default` and thus cannot be overridden or (2) all input types are known concretely. r? @nikomatsakis |
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CONTRIBUTING.md | ||
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LICENSE-MIT | ||
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RELEASES.md |
The Rust Programming Language
This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.
Quick Start
Read "Installing Rust" from The Book.
Building from Source
-
Make sure you have installed the dependencies:
g++
4.7 orclang++
3.xpython
2.7 (but not 3.x)- GNU
make
3.81 or later curl
git
-
Clone the source with
git
:$ git clone https://github.com/rust-lang/rust.git $ cd rust
-
Build and install:
$ ./configure $ make && make install
Note: You may need to use
sudo make install
if you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a--prefix
argument toconfigure
. Various other options are also supported – pass--help
for more information on them.When complete,
make install
will place several programs into/usr/local/bin
:rustc
, the Rust compiler, andrustdoc
, the API-documentation tool. This install does not include Cargo, Rust's package manager, which you may also want to build.
Building on Windows
There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by Visual Studio, and the GNU ABI used by the GCC toolchain. Which version of Rust you need depends largely on what C/C++ libraries you want to interoperate with: for interop with software produced by Visual Studio use the MSVC build of Rust; for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU build.
MinGW
MSYS2 can be used to easily build Rust on Windows:
-
Grab the latest MSYS2 installer and go through the installer.
-
From the MSYS2 terminal, install the
mingw64
toolchain and other required tools.# Update package mirrors (may be needed if you have a fresh install of MSYS2) $ pacman -Sy pacman-mirrors
Download MinGW from
here, and choose the
threads=win32,exceptions=dwarf/seh
flavor when installing. Also, make sure to install to a path without spaces in it. After installing,
add its bin
directory to your PATH
. This is due to #28260, in the future,
installing from pacman should be just fine.
# Make git available in MSYS2 (if not already available on path)
$ pacman -S git
$ pacman -S base-devel
-
Run
mingw32_shell.bat
ormingw64_shell.bat
from wherever you installed MSYS2 (i.e.C:\msys
), depending on whether you want 32-bit or 64-bit Rust. -
Navigate to Rust's source code, configure and build it:
$ ./configure $ make && make install
MSVC
MSVC builds of Rust additionally require an installation of Visual Studio 2013
(or later) so rustc
can use its linker. Make sure to check the “C++ tools”
option. In addition, cmake
needs to be installed to build LLVM.
With these dependencies installed, the build takes two steps:
$ ./configure
$ make && make install
Building Documentation
If you’d like to build the documentation, it’s almost the same:
./configure
$ make docs
Building the documentation requires building the compiler, so the above details will apply. Once you have the compiler built, you can
$ make docs NO_REBUILD=1
To make sure you don’t re-build the compiler because you made a change to some documentation.
The generated documentation will appear in a top-level doc
directory,
created by the make
rule.
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:
Platform \ Architecture | x86 | x86_64 |
---|---|---|
Windows (7, 8, Server 2008 R2) | ✓ | ✓ |
Linux (2.6.18 or later) | ✓ | ✓ |
OSX (10.7 Lion or later) | ✓ | ✓ |
You may find that other platforms work, but these are our officially supported build environments that are most likely to work.
Rust currently needs between 600MiB and 1.5GiB to build, depending on platform. If it hits swap, it will take a very long time to build.
There is more advice about hacking on Rust in CONTRIBUTING.md.
Getting Help
The Rust community congregates in a few places:
- Stack Overflow - Direct questions about using the language.
- users.rust-lang.org - General discussion and broader questions.
- /r/rust - News and general discussion.
Contributing
To contribute to Rust, please see CONTRIBUTING.
Rust has an IRC culture and most real-time collaboration happens in a variety of channels on Mozilla's IRC network, irc.mozilla.org. The most popular channel is #rust, a venue for general discussion about Rust, and a good place to ask for help.
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.