Go to file
bors 9ca75619dc Auto merge of #30652 - aturon:specialization, r=nikomatsakis
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
2016-03-14 17:55:41 -07:00
man Auto merge of #31433 - nagisa:fix-man-ur, r=brson 2016-02-07 10:33:36 +00:00
mk Auto merge of #30587 - oli-obk:eager_const_eval2, r=nikomatsakis 2016-03-14 11:38:23 -07:00
src Auto merge of #30652 - aturon:specialization, r=nikomatsakis 2016-03-14 17:55:41 -07:00
.gitattributes std: Remove msvc/valgrind headers 2015-07-27 16:21:15 -07:00
.gitignore Add *.pdb to .gitignore 2016-02-13 20:24:31 +01:00
.gitmodules Update .gitmodules 2016-02-20 20:37:30 +09:00
.mailmap Add another email address corresponding to Guillaume Gomez account 2016-02-18 11:38:59 +01:00
.travis.yml Use Travis trusty infrastructure 2015-10-19 18:31:02 -04:00
COMPILER_TESTS.md mention caveat about should-fail in docs 2016-03-03 11:18:42 -05:00
configure mk: Move disable-jemalloc logic into makefiles 2016-02-25 21:05:59 -08:00
CONTRIBUTING.md Update TESTNAME description 2016-02-02 10:58:59 +11:00
COPYRIGHT Mention initial copyright year 2016-01-28 09:44:04 +05:30
LICENSE-APACHE Update license, add license boilerplate to most files. Remainder will follow. 2012-12-03 17:12:14 -08:00
LICENSE-MIT Mention initial copyright year 2016-01-28 09:44:04 +05:30
Makefile.in mention debug-assertions 2016-02-25 10:21:32 +05:30
README.md Add note about avoiding spaces in MinGW install path 2016-03-05 14:10:25 +01:00
RELEASES.md Rollup merge of #31978 - tsion:patch-1, r=Manishearth 2016-03-01 13:39:42 -05:00

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

  1. Make sure you have installed the dependencies:

    • g++ 4.7 or clang++ 3.x
    • python 2.7 (but not 3.x)
    • GNU make 3.81 or later
    • curl
    • git
  2. Clone the source with git:

    $ git clone https://github.com/rust-lang/rust.git
    $ cd rust
    
  1. 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 to configure. 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, and rustdoc, 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:

  1. Grab the latest MSYS2 installer and go through the installer.

  2. 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
  1. Run mingw32_shell.bat or mingw64_shell.bat from wherever you installed MSYS2 (i.e. C:\msys), depending on whether you want 32-bit or 64-bit Rust.

  2. 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 youd like to build the documentation, its 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 dont 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:

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.