- Enable ccache for Travis CI

- GCC build on Travis CI actually chooses gcc as compiler (before, it was still clang somehow)
- Disable GCC build on Travis because gcc on osx is broken

.travis.yml

@@ -2,7 +2,7 @@ language: cpp
 sudo: required
 dist: trusty
 compiler:
-- gcc
+# - gcc
 - clang
 os:
 #- linux
@@ -21,3 +21,4 @@ install:
 - .travisci/install.sh
 script:
 - .travisci/build_and_test.sh
+cache: ccache

.travisci/build_and_test.sh

@@ -1,6 +1,31 @@
 #!/bin/bash
 
-set -e
+set -ev
+
+# Use new clang on linux
+if [ "${TRAVIS_OS_NAME}" == "linux" ] && [ "$CXX" == "clang++" ]; then
+  echo Switch to Clang 3.7
+  export CXX="clang++-3.7" CC="clang-3.7"
+else
+  echo Do not switch to Clang 3.7 because we are either not Linux or not Clang.
+fi
+
+# If using gcc on mac, actually use it ("gcc" just links to clang, but "gcc-4.8" is gcc, https://github.com/travis-ci/travis-ci/issues/2423)
+# Note: This must be here and not in install.sh, because environment variables can't be passed between scripts.
+if [ "${TRAVIS_OS_NAME}" == "osx" ] && [ "${CXX}" == "g++" ]; then
+  echo Switch to actual g++ and not just the AppleClang symlink
+  export CXX="g++-7" CC="gcc-7"
+else
+  echo Do not switch to actual g++ because we are either not osx or not g++
+fi
+
+# Setup ccache
+export PATH="/usr/local/opt/ccache/libexec:$PATH"
+export CCACHE_COMPILERCHECK=content
+export CCACHE_COMPRESS=1
+export CCACHE_SLOPPINESS=include_file_mtime
+ccache --max-size=512M
+ccache --show-stats
 
 # Detect number of CPU cores
 export NUMCORES=`grep -c ^processor /proc/cpuinfo`
@@ -9,6 +34,8 @@ if [ ! -n "$NUMCORES" ]; then
 fi
 echo Using $NUMCORES cores
 
+echo Using CXX compiler $CXX and C compiler $CC
+
 # Setup target directory
 mkdir cmake
 cd cmake
@@ -18,6 +45,8 @@ cmake --version
 cmake .. -DBUILD_TESTING=on -DCMAKE_BUILD_TYPE=Debug
 make -j$NUMCORES
 
+ccache --show-stats
+
 # Test
 ./test/gitversion/gitversion-test
 ./test/cpp-utils/cpp-utils-test

.travisci/install.sh

@@ -2,21 +2,19 @@
 
 set -e
 
-# Use new clang on linux
-if [ "${TRAVIS_OS_NAME}" == "linux" ] && [ "$CXX" = "clang++" ]; then
-  export CXX="clang++-3.7" CC="clang-3.7"
-fi
-
-# If using gcc on mac, actually use it ("gcc" just links to clang, but "gcc-4.8" is gcc, https://github.com/travis-ci/travis-ci/issues/2423)
-if [ "${TRAVIS_OS_NAME}" == "osx" ] && ["${CXX}" = "g++" ]; then
-  export CXX="g++-4.8" CC="gcc-4.8"
-fi
-
 # Install dependencies
 if [ "${TRAVIS_OS_NAME}" == "linux" ]; then
   ./.travisci/install_boost.sh
 fi
 
+# Install newer GCC if we're running on GCC osx
+if [ "${TRAVIS_OS_NAME}" == "osx" ] && [ "${CXX}" == "g++" ]; then
+    # We need to uninstall oclint because it creates a /usr/local/include/c++ symlink that clashes with the gcc5 package
+    # see https://github.com/Homebrew/homebrew-core/issues/21172
+    brew cask uninstall oclint
+    brew install gcc@7
+fi
+
 if [ "${TRAVIS_OS_NAME}" == "osx" ]; then
   brew cask install osxfuse
   brew install libomp
@@ -29,3 +27,6 @@ git fetch --unshallow
 if [ "${TRAVIS_OS_NAME}" == "linux" ]; then
   sudo cp -a /dev/urandom /dev/random
 fi
+
+# Setup ccache
+brew install ccache