bors 8b3705528a Auto merge of #27416 - alexcrichton:fix-dll-export, r=brson
These two commits are aimed at "fixing" our usage of `dllexport` in the compiler. Currently we blanket apply this attribute to *everything* public in a crate, but this ends up with a few downsides:

* Executables are larger than the should be as a result of thinking they should export everything
* Native libraries aren't handled correctly because technically a statically included native library should be exported from a DLL in some cases.
* Symbols don't actually need to be exported if they never end up in a DLL.

The first commit adds a new unstable attribute, `#[linked_from]`, which is a way to tell the compiler what native library a block of symbols comes from. This is used to inform the compiler what set of native libraries are statically included in the rlib (or other output). This information is later used to export them from a DLL if necessary. Currently this is only used in a few places (such as the LLVM bindings) to get the compiler to link correctly.

The second commit stops adding `dllexport` to all items in LLVM and instead explicitly telling the linker what symbols should be exported. We only need to do this when building a dynamic library, and otherwise we can avoid adding `dllexport` or telling the linker about exported symbols.

As a testament to this change, the size of "Hello World" on MSVC drops from 1.2MB to 67KB as a result of this patch. This is because the linker can much more aggressively remove unused code.

These commits do not yet attempt to fix our story with `dllimport`, and I'll leave that to a future PR and issue, for now though I'm going to say that this

Closes #7196
2015-08-11 02:10:31 +00:00

The Rust Programming Language

Rust is a fast systems programming language that guarantees memory safety and offers painless concurrency (no data races). It does not employ a garbage collector and has minimal runtime overhead.

This repo contains the code for the compiler (rustc), as well as standard libraries, tools and documentation for Rust.

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 2.6 or later (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

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.

    # Choose one based on platform:
    $ pacman -S mingw-w64-i686-toolchain
    $ pacman -S mingw-w64-x86_64-toolchain
    
    $ pacman -S base-devel
    
  3. 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.

  4. Navigate to 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:

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 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 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.

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