ci: configs for clang-3.8 and gcc-4.8 builds (#253)

Just more builds, these are important because some of the other projects
have them, and they break when a new release of `-common` cannot compile
with those compilers. We just had that happen with `-pubsub`. There are
some formatting changes triggered by the double braces, I chose not to
argue with clang-format (I never do).

Author: coryan

ci/kokoro/docker/Dockerfile.centos

@@ -0,0 +1,26 @@
+# Copyright 2020 Google LLC
+#
+# 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.
+
+ARG DISTRO_VERSION=7
+FROM centos:${DISTRO_VERSION}
+
+# We need to install cmake3, which on CentOS-7 requires an extra source
+RUN rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
+RUN yum install -y centos-release-scl
+RUN yum-config-manager --enable rhel-server-rhscl-7-rpms
+
+RUN yum makecache && \
+    yum install -y automake cmake3 curl-devel gcc gcc-c++ git libtool \
+        make openssl-devel pkgconfig tar wget which zlib-devel
+RUN ln -sf /usr/bin/cmake3 /usr/bin/cmake && ln -sf /usr/bin/ctest3 /usr/bin/ctest

ci/kokoro/docker/Dockerfile.ubuntu

@@ -17,8 +17,6 @@ FROM ubuntu:${DISTRO_VERSION}
 
 RUN apt-get update && \
     apt-get --no-install-recommends install -y \
-        abi-compliance-checker \
-        abi-dumper \
         apt-transport-https \
         apt-utils \
         automake \
@@ -28,13 +26,11 @@ RUN apt-get update && \
         clang \
         cmake \
         curl \
-        ctags \
         doxygen \
         gawk \
         git \
         gcc \
         g++ \
-        cmake \
         libssl-dev \
         libtool \
         lsb-release \

ci/kokoro/docker/build.sh

@@ -168,6 +168,26 @@ elif [[ "${BUILD_NAME}" = "scan-build" ]]; then
   export CC=clang
   export CXX=clang++
   export SCAN_BUILD=yes
+elif [[ "${BUILD_NAME}" = "gcc-4.8" ]]; then
+  # The oldest version of GCC we support is 4.8, this build checks the code
+  # against that version. The use of CentOS 7 for that build is not a
+  # coincidence: the reason we support GCC 4.8 is to support this distribution
+  # (and its commercial cousin: RHEL 7).
+  export DISTRO=centos
+  export DISTRO_VERSION=7
+  export CMAKE_SOURCE_DIR="super"
+  in_docker_script="ci/kokoro/docker/build-in-docker-cmake.sh"
+elif [[ "${BUILD_NAME}" = "clang-3.8" ]]; then
+  # The oldest version of Clang we actively test is 3.8. There is nothing
+  # particularly interesting about that version. It is simply the version
+  # included with Ubuntu:16.04, and the oldest version tested by
+  # google-cloud-cpp-common.
+  export DISTRO=ubuntu
+  export DISTRO_VERSION=16.04
+  export CC=clang
+  export CXX=clang++
+  export CMAKE_SOURCE_DIR="super"
+  in_docker_script="ci/kokoro/docker/build-in-docker-cmake.sh"
 elif [[ "${BUILD_NAME}" = "cxx17" ]]; then
   export GOOGLE_CLOUD_CPP_CXX_STANDARD=17
   export TEST_INSTALL=yes
@@ -237,6 +257,7 @@ docker_build_flags=(
   # upload it.
   "-t" "${IMAGE}:latest"
   "--build-arg" "NCPU=${NCPU}"
+  "--build-arg" "DISTRO_VERSION=${DISTRO_VERSION}"
   "-f" "ci/kokoro/docker/Dockerfile.${DISTRO}"
 )
 

ci/kokoro/docker/clang-3.8-presubmit.cfg

@@ -67,7 +67,8 @@ std::chrono::system_clock::time_point ParseDateTime(
     ReportError(timestamp, "Invalid date-time separator, expected 'T' or 't'.");
   }
 
-  std::array<int, kMonthsInYear> constexpr kMaxDaysInMonth{
+  // Double braces are needed to workaround a clang-3.8 bug.
+  std::array<int, kMonthsInYear> constexpr kMaxDaysInMonth{{
       31,  // January
       29,  // February (non-leap years checked below)
       31,  // March
@@ -80,7 +81,7 @@ std::chrono::system_clock::time_point ParseDateTime(
       31,  // October
       30,  // November
       31,  // December
-  };
+  }};
   auto constexpr kMkTimeBaseYear = 1900;
   if (month < 1 || month > kMonthsInYear) {
     ReportError(timestamp, "Out of range month.");

ci/kokoro/docker/clang-3.8.cfg

@@ -29,10 +29,18 @@ static_assert(static_cast<int>(Severity::GCP_LS_LOWEST) <
 std::ostream& operator<<(std::ostream& os, Severity x) {
   auto constexpr kSeverityCount =
       static_cast<int>(Severity::GCP_LS_HIGHEST) + 1;
-  std::array<char const*, kSeverityCount> names{
-      "TRACE", "DEBUG",    "INFO",  "NOTICE", "WARNING",
-      "ERROR", "CRITICAL", "ALERT", "FATAL",
-  };
+  // Double braces needed to workaround a clang-3.8 bug.
+  std::array<char const*, kSeverityCount> names{{
+      "TRACE",
+      "DEBUG",
+      "INFO",
+      "NOTICE",
+      "WARNING",
+      "ERROR",
+      "CRITICAL",
+      "ALERT",
+      "FATAL",
+  }};
   auto index = static_cast<int>(x);
   return os << names[index];
 }