add some notes on coding conventions and link to copyright notice

Author: nikomatsakis

src/SUMMARY.md

@@ -2,6 +2,7 @@
 
 - [About this guide](./about-this-guide.md)
 - [How to build the compiler and run what you built](./how-to-build-and-run.md)
+- [Coding conventions](./conventions.md)
 - [The compiler testing framework](./tests/intro.md)
     - [Running tests](./tests/running.md)
     - [Adding new tests](./tests/adding.md)

src/conventions.md

@@ -0,0 +1,63 @@
+rustc is slowly moving towards the [Rust standard coding style][fmt];
+at the moment, however, it follows a rather more *chaotic*
+style. There are a few things that are always true.
+
+[fmt]: https://github.com/rust-lang-nursery/fmt-rfcs
+
+# The tidy script
+
+Running `./x.py test` begins with a "tidy" step. This tidy step checks
+that your source files meet some basic conventions.
+
+<a name=copyright>
+
+## Copyright notice
+
+All files must begin with the following copyright notice:
+
+```
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+```
+
+The year at the top is not meaningful: copyright protections are in
+fact automatic from the moment of authorship. We do not typically edit
+the years on existing files. When creating a new file, you can use the
+current year if you like, but you don't have to.
+
+## Line length
+
+Lines should be at most 100 characters. It's even better if you can
+keep things to 80.
+
+**Ignoring the line length limit.** Sometimes -- in particular for
+tests -- it can be necessary to exempt yourself from this limit. In
+that case, you can add a comment towards the top of the file (after
+the copyright notice) like so:
+
+```
+// ignore-tidy-linelength
+```
+
+## Tabs vs spaces
+
+Prefer 4-space indent.
+
+# Warnings and lints
+
+In general, Rust crates 
+
+# Policy on using crates from crates.io
+
+It is allowed to use crates from crates.io, though external
+dependencies should not be added gratuitously. All such crates must
+have a suitably permissive license. There is an automatic check which
+inspects the Cargo metadata to ensure this.
+

src/tests/adding.md

@@ -9,7 +9,7 @@ To add a new test, the first thing you generally do is to create a
 file, typically a Rust source file. Test files have a particular
 structure:
 
-- They always begin with the copyright notice;
+- They always begin with the [copyright notice](../conventions.html#copyright);
 - then they should have some kind of
   [comment explaining what the test is about](#explanatory_comment);
 - next, they can have one or more [header commands](#header_commands), which are special