[CI] Add lint stage

* Add scripts for Travis under ./scripts/travis
* Install rustfmt and clippy on nightly
* Lint code for formatting problems and common errors

.travis.yml

@@ -1,9 +1,19 @@
 language: rust
+
 rust:
   - stable
   - beta
   - nightly
+
+cache: cargo
+
 matrix:
   allow_failures:
     - rust: nightly
     - rust: beta
+
+before_script:
+  - NO_RUSTUP=1 ./scripts/travis/before_script.sh
+
+script:
+  - NO_RUSTUP=1 ./scripts/travis/script.sh

Makefile

@@ -11,7 +11,11 @@ RUSTUP_INSTALLED = $(shell command -v rustup 2> /dev/null)
 ifndef RUSTUP_INSTALLED
   CARGO = cargo
 else
-  CARGO = rustup run $(RUST_CHANNEL) cargo
+  ifdef NO_RUSTUP
+    CARGO = cargo
+  else
+    CARGO = rustup run $(RUST_CHANNEL) cargo
+  endif
 endif
 
 

scripts/travis/before_script.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+set -eu
+
+export PATH="$PATH:$HOME/.cargo/bin"
+if [[ "$TRAVIS_RUST_VERSION" == "nightly" ]]; then
+  make install
+fi

scripts/travis/script.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+set -eu
+
+make build
+make test
+if [[ "$TRAVIS_RUST_VERSION" == "nightly" ]]; then
+  make lint
+fi