Merge pull request #428 from RalfJung/toolchain

document and fully use rust-toolchain file

.travis.yml

@@ -11,6 +11,8 @@ before_script:
 # mac os weirdness (https://github.com/travis-ci/travis-ci/issues/6307)
 - curl -sSL https://rvm.io/mpapis.asc | gpg --import -
 - rvm get stable
+# in a cronjob, use latest (not pinned) nightly
+- if [ "$TRAVIS_EVENT_TYPE" = cron ]; then rustup override set nightly; fi
 # actual travis code
 - export PATH=$HOME/.local/bin:$PATH
 - rustup target add i686-unknown-linux-gnu

README.md

@@ -5,35 +5,16 @@ An experimental interpreter for [Rust][rust]'s [mid-level intermediate
 representation][mir] (MIR). This project began as part of my work for the
 undergraduate research course at the [University of Saskatchewan][usask].
 
-## Installing Rust
-
-I recommend that you install [rustup][rustup] and then use it to install the
-current Rust nightly version:
-
-```sh
-rustup update nightly
-```
-
-You should also make `nightly` the default version for your Miri directory by
-running the following command while you're in it. If you don't do this, you can
-run the later `cargo` commands by using `cargo +nightly` instead.
-
-```sh
-rustup override add nightly
-```
-
 ## Building Miri
 
+I recommend that you install [rustup][rustup] to obtain Rust.  miri comes with a
+`rust-toolchain` file so rustup will automatically pick a suitable nightly
+version.  Then all you have to do is:
+
 ```sh
 cargo build
 ```
 
-If Miri fails to build, it's likely because a change in the latest nightly
-compiler broke it. You could try an older nightly with `rustup update
-nightly-<date>` where `<date>` is a few days or weeks ago, e.g. `2016-05-20` for
-May 20th. Otherwise, you could notify me in an issue or on IRC. Or, if you know
-how to fix it, you could send a PR. :smile:
-
 ## Running tests
 
 ```sh

rust-toolchain

@@ -1 +1 @@
-nightly
+nightly-2018-08-03