Travis CI: Install latest CMake

.travis.yml

@@ -140,9 +140,11 @@ cache:
     directories:
         - boost_1_57_0
         - build
+        - $HOME/.local
 
 install:
     - test $TRAVIS_INSTALL_DEPS != On || ./scripts/install_deps.sh
+    - test "$TRAVIS_OS_NAME" != "linux" || ./scripts/install_cmake.sh
     - echo -n "$TRAVIS_COMMIT" > commit_hash.txt
 before_script:
     - test $TRAVIS_EMSCRIPTEN != On || ./scripts/build_emscripten.sh

scripts/install_cmake.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env sh
+
+# This script downloads the CMake binary and installs it in ~/.local directory
+# (the cmake executable will be in ~/.local/bin).
+# This is mostly suitable for CIs, not end users.
+
+set -e
+
+VERSION=3.7.1
+PREFIX=~/.local
+
+OS=$(uname -s)
+case $OS in
+Linux)  SHA256=7b4b7a1d9f314f45722899c0521c261e4bfab4a6b532609e37fef391da6bade2;;
+Darwin) SHA256=1851d1448964893fdc5a8c05863326119f397a3790e0c84c40b83499c7960267;;
+esac
+
+
+BIN=$PREFIX/bin
+
+if test -f $BIN/cmake && ($BIN/cmake --version | grep -q "$VERSION"); then
+    echo "CMake $VERSION already installed in $BIN"
+else
+    FILE=cmake-$VERSION-$OS-x86_64.tar.gz
+    URL=https://cmake.org/files/v3.7/$FILE
+    ERROR=0
+    TMPFILE=$(mktemp --tmpdir cmake-$VERSION-$OS-x86_64.XXXXXXXX.tar.gz)
+    echo "Downloading CMake ($URL)..."
+    wget "$URL" -O "$TMPFILE" -nv
+    if ! (shasum -a256 "$TMPFILE" | grep -q "$SHA256"); then
+        echo "Checksum mismatch ($TMPFILE)"
+        exit 1
+    fi
+    mkdir -p "$PREFIX"
+    tar xzf "$TMPFILE" -C "$PREFIX" --strip 1
+    rm $TMPFILE
+fi