Run many parallel CI jobs

Our CI is performing multiple different jobs:

* For every libclang version we support:
  * With both debug and release profiles:
    * Generating bindings from our test headers, with and without extra
      assertions, and asserting there is no diff from the expectations.
    * Compiling and testing the generated bindings.
    * Compiling and testing the bindgen-integration crate.
* Testing the md book.
* Asserting that there aren't any system includes in any of the test headers.
* Asserting that all the pub functions have doc comments.

We were previously doing these things sequentially for each libclang
version. This commit breaks these jobs up explicitly and runs each of them one
at a time so that they can each be run in parallel, on different Travis CI
machines.

.travis.yml

@@ -17,12 +17,32 @@ env:
   global:
     - CARGO_TARGET_DIR=/tmp/bindgen
   matrix:
-    - LLVM_VERSION=3.8.1
-    - LLVM_VERSION=3.9.0
-    - LLVM_VERSION=4.0.0
+    - LLVM_VERSION="3.8.1" BINDGEN_JOB="test"         BINDGEN_PROFILE=
+    - LLVM_VERSION="3.8.1" BINDGEN_JOB="test"         BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="3.8.1" BINDGEN_JOB="integration"  BINDGEN_PROFILE=
+    - LLVM_VERSION="3.8.1" BINDGEN_JOB="integration"  BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="3.8.1" BINDGEN_JOB="expectations" BINDGEN_PROFILE=
+    - LLVM_VERSION="3.8.1" BINDGEN_JOB="expectations" BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="3.9.0" BINDGEN_JOB="test"         BINDGEN_PROFILE=
+    - LLVM_VERSION="3.9.0" BINDGEN_JOB="test"         BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="3.9.0" BINDGEN_JOB="integration"  BINDGEN_PROFILE=
+    - LLVM_VERSION="3.9.0" BINDGEN_JOB="integration"  BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="3.9.0" BINDGEN_JOB="expectations" BINDGEN_PROFILE=
+    - LLVM_VERSION="3.9.0" BINDGEN_JOB="expectations" BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="test"         BINDGEN_PROFILE=
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="test"         BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="test"         BINDGEN_PROFILE=            BINDGEN_FEATURES="testing_only_extra_assertions"
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="test"         BINDGEN_PROFILE="--release" BINDGEN_FEATURES="testing_only_extra_assertions"
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="integration"  BINDGEN_PROFILE=
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="integration"  BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="expectations" BINDGEN_PROFILE=
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="expectations" BINDGEN_PROFILE="--release"
+    - LLVM_VERSION="4.0.0" BINDGEN_JOB="misc"
 
 matrix:
   fast_finish: true
+  allow_failures:
+    - env: LLVM_VERSION=4.0.0 BINDGEN_JOB=rustfmt
 
 cache:
   directories:
@@ -32,14 +52,12 @@ cache:
 before_install: . ./ci/before_install.sh
 
 script:
-  # - ./ci/assert-rustfmt.sh
-  - BINDGEN_FEATURES="$BINDGEN_FEATURES" ./ci/assert-docs.sh
-  - BINDGEN_FEATURES="$BINDGEN_FEATURES" ./ci/test.sh
-  - ./ci/test-book.sh
+  - BINDGEN_JOB="$BINDGEN_JOB" BINDGEN_PROFILE="$BINDGEN_PROFILE" BINDGEN_FEATURES="$BINDGEN_FEATURES" ./ci/script.sh
 
 after_success:
   - test "$TRAVIS_PULL_REQUEST" == "false" &&
     test "$TRAVIS_BRANCH" == "master" &&
+    test "$BINDGEN_JOB" == "misc" &&
     ./ci/deploy-book.sh
 
 notifications:

ci/script.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+
+set -xeu
+cd "$(dirname "$0")/.."
+
+# Note that `$BINDGEN_PROFILE` is never in quotes so that it expands to nothing
+# (not even an empty string argument) when the variable is empty. This is
+# necessary so we don't pass an unexpected flag to cargo.
+
+export RUST_BACKTRACE=1
+
+case "$BINDGEN_JOB" in
+    "test")
+        cargo test $BINDGEN_PROFILE --features "$BINDGEN_FEATURES"
+        ./ci/assert-no-diff.sh
+        ;;
+
+    "integration")
+        cd ./bindgen-integration
+        cargo test $BINDGEN_PROFILE --features "$BINDGEN_FEATURES"
+        ;;
+
+    "expectations")
+        cd ./tests/expectations
+        cargo test $BINDGEN_PROFILE
+        ;;
+
+    "misc")
+        ./ci/assert-docs.sh
+        ./ci/test-book.sh
+        ./ci/no-includes.sh
+        # `rustfmt` isn't reaching a fixed point on bindgen
+        # code... https://github.com/rust-lang-nursery/rustfmt/issues/1376
+        # ./ci/assert-rustfmt.sh
+        ;;
+
+    *)
+        echo "Error! Unknown \$BINDGEN_JOB: '$BINDGEN_JOB'"
+        exit 1
+esac