Use CMake 3.2. (#1332)

CMakeLists.txt

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-cmake_minimum_required(VERSION 2.8.12)  # Ships with Ubuntu 14.04 (Trusty)
+cmake_minimum_required(VERSION 3.2)
 
 project(cartographer)
 

cmake/modules/FindEigen3.cmake

@@ -0,0 +1,30 @@
+# Copyright 2018 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+find_package(Eigen3 QUIET NO_MODULE)
+if (NOT EIGEN3_FOUND)
+  list(APPEND EIGEN3_POSSIBLE_DIRS
+    /usr/local/include/eigen3
+    /usr/include/eigen3
+  )
+  find_path(EIGEN3_INCLUDE_DIR
+    NAMES Eigen/Core
+    PATHS ${EIGEN3_POSSIBLE_DIRS}
+  )
+  if (EIGEN3_INCLUDE_DIR AND EXISTS ${EIGEN3_INCLUDE_DIR})
+    set(EIGEN3_FOUND TRUE)
+  else()
+    message(WARNING "Failed to find Eigen3. Please, define the path manually.")
+  endif()
+endif()

scripts/install_debs_cmake.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 # Copyright 2016 The Cartographer Authors
 #
@@ -19,8 +19,22 @@ set -o verbose
 
 # Install the required libraries that are available as debs.
 sudo apt-get update
+
+# Install CMake 3.2 for Ubuntu Trusty and Debian Jessie.
+sudo apt-get install lsb-release -y
+if [[ "$(lsb_release -sc)" = "trusty" ]]
+then
+  sudo apt-get install cmake3 -y
+elif [[ "$(lsb_release -sc)" = "jessie" ]]
+then
+  sudo sh -c "echo 'deb http://ftp.debian.org/debian jessie-backports main' >> /etc/apt/sources.list"
+  sudo apt-get update
+  sudo apt-get -t jessie-backports install cmake -y
+else
+  sudo apt-get install cmake -y
+fi
+
 sudo apt-get install -y \
-    cmake \
     g++ \
     git \
     google-mock \