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Felix S. Klock II 5b2e8693e4 Reject specialized Drop impls. See Issue 8142 for discussion. This makes it illegal for a Drop impl to be more specialized than the original item. So for example, all of the following are now rejected (when they would have been blindly accepted before): ```rust struct S<A> { ... }; impl Drop for S<i8> { ... } // error: specialized to concrete type struct T<'a> { ... }; impl Drop for T<'static> { ... } // error: specialized to concrete region struct U<A> { ... }; impl<A:Clone> Drop for U<A> { ... } // error: added extra type requirement struct V<'a,'b>; impl<'a,'b:a> Drop for V<'a,'b> { ... } // error: added extra region requirement ``` Due to examples like the above, this is a [breaking-change]. (The fix is to either remove the specialization from the `Drop` impl, or to transcribe the requirements into the struct/enum definition; examples of both are shown in the PR's fixed to `libstd`.) ---- This is likely to be the last thing blocking the removal of the `#[unsafe_destructor]` attribute. Includes two new error codes for the new dropck check. Update run-pass tests to accommodate new dropck pass. Update tests and docs to reflect new destructor restriction. ---- Implementation notes: We identify Drop impl specialization by not being as parametric as the struct/enum definition via unification. More specifically: 1. Attempt unification of a skolemized instance of the struct/enum with an instance of the Drop impl's type expression where all of the impl's generics (i.e. the free variables of the type expression) have been replaced with unification variables. 2. If unification fails, then reject Drop impl as specialized. 3. If unification succeeds, check if any of the skolemized variables "leaked" into the constraint set for the inference context; if so, then reject Drop impl as specialized. 4. Otherwise, unification succeeded without leaking skolemized variables: accept the Drop impl. We identify whether a Drop impl is injecting new predicates by simply looking whether the predicate, after an appropriate substitution, appears on the struct/enum definition.		2015-03-24 22:27:23 +01:00
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README.md

The Rust Programming Language

This is a compiler for Rust, including standard libraries, tools and documentation. Rust is a systems programming language that is fast, memory safe and multithreaded, but does not employ a garbage collector or otherwise impose significant runtime overhead.

Quick Start

Read "Installing Rust" from The Book.

Building from Source

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

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 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:

Grab the latest MSYS2 installer and go through the installer.

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

Run mingw32_shell.bat or mingw64_shell.bat from wherever you installed MYSY2 (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
```

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 and x86-64 (64-bit support added in Rust 0.12.0)
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 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.

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