From b8228ee6564f5a7ad0d6d0b9a30516521cff2ee9 Mon Sep 17 00:00:00 2001
From: Wolfgang Hess <whess@lyft.com>
Date: Fri, 7 May 2021 15:52:57 +0200
Subject: [PATCH] Remove Ubuntu Xenial from CI. (#1833)

Ubuntu 16.04 has reached end of standard support.

Signed-off-by: Wolfgang Hess <whess@lyft.com>
---
 .travis.yml           |  1 -
 Dockerfile.xenial     | 36 ------------------------------------
 cmake/functions.cmake |  4 ----
 docs/source/index.rst |  6 +++---
 4 files changed, 3 insertions(+), 44 deletions(-)
 delete mode 100644 Dockerfile.xenial

diff --git a/.travis.yml b/.travis.yml
index 987d35c..8dc1031 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,7 +22,6 @@ cache:
     - /home/travis/docker/
 
 env:
-  - LSB_RELEASE=xenial DOCKER_CACHE_FILE=/home/travis/docker/xenial-cache.tar.gz CC=gcc CXX=g++
   - LSB_RELEASE=bionic DOCKER_CACHE_FILE=/home/travis/docker/bionic-cache.tar.gz CC=gcc CXX=g++
   - LSB_RELEASE=focal DOCKER_CACHE_FILE=/home/travis/docker/focal-cache.tar.gz CC=gcc CXX=g++
   - LSB_RELEASE=stretch DOCKER_CACHE_FILE=/home/travis/docker/stretch-cache.tar.gz CC=gcc CXX=g++
diff --git a/Dockerfile.xenial b/Dockerfile.xenial
deleted file mode 100644
index 83620f9..0000000
--- a/Dockerfile.xenial
+++ /dev/null
@@ -1,36 +0,0 @@
-# Copyright 2016 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.
-
-FROM ubuntu:xenial
-
-ARG cc
-ARG cxx
-
-# Set the preferred C/C++ compiler toolchain, if given (otherwise default).
-ENV CC=$cc
-ENV CXX=$cxx
-
-# This base image doesn't ship with sudo.
-RUN apt-get update && apt-get install -y sudo && rm -rf /var/lib/apt/lists/*
-
-COPY scripts/install_debs_cmake.sh cartographer/scripts/
-RUN cartographer/scripts/install_debs_cmake.sh && rm -rf /var/lib/apt/lists/*
-COPY scripts/install_abseil.sh cartographer/scripts/
-RUN cartographer/scripts/install_abseil.sh && rm -rf /var/lib/apt/lists/*
-COPY scripts/install_ceres.sh cartographer/scripts/
-RUN cartographer/scripts/install_ceres.sh && rm -rf ceres-solver
-COPY scripts/install_proto3.sh cartographer/scripts/
-RUN cartographer/scripts/install_proto3.sh && rm -rf protobuf
-COPY . cartographer
-RUN cartographer/scripts/install_cartographer_cmake.sh && rm -rf cartographer
diff --git a/cmake/functions.cmake b/cmake/functions.cmake
index 1bbce43..b3f57e8 100644
--- a/cmake/functions.cmake
+++ b/cmake/functions.cmake
@@ -78,10 +78,6 @@ macro(google_initialize_cartographer_project)
   else()
     set(GOOG_CXX_FLAGS "-pthread -fPIC ${GOOG_CXX_FLAGS}")
 
-    if (CMAKE_CXX_COMPILER_ID MATCHES "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 6.1)
-      google_add_flag(GOOG_CXX_FLAGS "-std=c++11")
-    endif()
-
     google_add_flag(GOOG_CXX_FLAGS "-Wall")
     google_add_flag(GOOG_CXX_FLAGS "-Wpedantic")
 
diff --git a/docs/source/index.rst b/docs/source/index.rst
index 8de158a..4871233 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -65,7 +65,7 @@ Getting started without ROS
 Please see our ROS integration as a starting point for integrating your system
 with the standalone library. Currently, it is the best available reference.
 
-On Ubuntu 16.04 (Xenial):
+On Ubuntu 18.04 (Bionic):
 
 .. literalinclude:: ../../scripts/install_debs_cmake.sh
   :language: bash
@@ -97,8 +97,8 @@ on systems that meet the following requirements:
 
 * 64-bit, modern CPU (e.g. 3rd generation i7)
 * 16 GB RAM
-* Ubuntu 16.04 (Xenial), 18.04 (Bionic), 20.04 (Focal)
-* gcc version 4.8.4, 5.4.0, 7.5.0, 9.3.0
+* Ubuntu 18.04 (Bionic), 20.04 (Focal)
+* gcc version 6.3.0, 7.5.0, 9.3.0
 
 Known Issues
 ------------