[Travis] Modernize the Travis build

Drop old compilers and add new ones. Also bump the minimum CMake version.

.travis.yml

@@ -9,24 +9,12 @@ sudo: false
 matrix:
   include:
     - os: linux
-      env: LLVM_VERSION=3.6.2
-      addons: { apt: { packages: ["clang-3.6"], sources: ["llvm-toolchain-precise-3.6", "ubuntu-toolchain-r-test"] } }
+      env: LLVM_VERSION=7.0.0
+      addons: { apt: { packages: ["clang-7"], sources: ["llvm-toolchain-trusty-7", "ubuntu-toolchain-r-test"] } }
 
     - os: linux
-      env: LLVM_VERSION=3.7.1
-      addons: { apt: { packages: ["clang-3.7"], sources: ["llvm-toolchain-precise-3.7", "ubuntu-toolchain-r-test"] } }
-
-    - os: linux
-      env: LLVM_VERSION=3.8.1
-      addons: { apt: { packages: ["clang-3.8"], sources: ["llvm-toolchain-precise-3.8", "ubuntu-toolchain-r-test"] } }
-
-    - os: linux
-      env: LLVM_VERSION=3.9.1
-      addons: { apt: { packages: ["clang-3.9"], sources: ["llvm-toolchain-precise-3.9", "ubuntu-toolchain-r-test"] } }
-
-    - os: linux
-      env: LLVM_VERSION=4.0.0
-      addons: { apt: { packages: ["clang-4.0"], sources: ["llvm-toolchain-trusty-4.0", "ubuntu-toolchain-r-test"] } }
+      env: LLVM_VERSION=8.0.0
+      addons: { apt: { packages: ["clang-8"], sources: ["llvm-toolchain-trusty-8", "ubuntu-toolchain-r-test"] } }
 
     - os: linux
       env: COMPILER=g++-5
@@ -36,14 +24,19 @@ matrix:
       env: COMPILER=g++-6
       addons: { apt: { packages: ["g++-6"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    - os: osx
-      osx_image: xcode7.3
+    - os: linux
+      env: COMPILER=g++-7
+      addons: { apt: { packages: ["g++-7"], sources: ["ubuntu-toolchain-r-test"] } }
+
+    - os: linux
+      env: COMPILER=g++-8
+      addons: { apt: { packages: ["g++-8"], sources: ["ubuntu-toolchain-r-test"] } }
 
     - os: osx
-      osx_image: xcode8.3
+      osx_image: xcode9.4
 
     - os: osx
-      osx_image: xcode9.1
+      osx_image: xcode10.2
 
 
 install:
@@ -57,13 +50,13 @@ install:
   # Pick up the overriden compiler if any
   ############################################################################
   - if [[ "${COMPILER}" != "" ]]; then export CXX=${COMPILER}; fi
-  - if [[ "${LLVM_VERSION}" != "" ]]; then export CXX="clang++-${LLVM_VERSION%.[0-9]}"; fi
+  - if [[ "${LLVM_VERSION}" != "" ]]; then export CXX="clang++-${LLVM_VERSION%.[0-9].[0-9]}"; fi
   - ${CXX} --version
 
   ############################################################################
   # Install a recent CMake (unless already installed on OS X)
   ############################################################################
-  - CMAKE_VERSION=3.8.0
+  - CMAKE_VERSION=3.10.0
   - |
     if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
       CMAKE_URL="https://cmake.org/files/v${CMAKE_VERSION%.[0-9]}/cmake-${CMAKE_VERSION}-Linux-x86_64.tar.gz"

CMakeLists.txt

@@ -2,7 +2,7 @@
 # Distributed under the Boost Software License, Version 1.0.
 # See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt
 
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.10)
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 project(awful LANGUAGES CXX)