# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you 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.
#
# Sets COMPILER_FAMILY to 'clang' or 'gcc'
# Sets COMPILER_VERSION to the version
execute_process(COMMAND env LANG=C "${CMAKE_CXX_COMPILER}" -v
                ERROR_VARIABLE COMPILER_VERSION_FULL)
message(${COMPILER_VERSION_FULL})

# clang on Linux and Mac OS X before 10.9
if("${COMPILER_VERSION_FULL}" MATCHES ".*clang version.*")
  set(COMPILER_FAMILY "clang")
  string(REGEX REPLACE ".*clang version ([0-9]+\\.[0-9]+).*" "\\1"
    COMPILER_VERSION "${COMPILER_VERSION_FULL}")
# clang on Mac OS X 10.9 and later
elseif("${COMPILER_VERSION_FULL}" MATCHES ".*based on LLVM.*")
  set(COMPILER_FAMILY "clang")
  string(REGEX REPLACE ".*based on LLVM ([0-9]+\\.[0.9]+).*" "\\1"
    COMPILER_VERSION "${COMPILER_VERSION_FULL}")

# clang on Mac OS X, XCode 7.
elseif("${COMPILER_VERSION_FULL}" MATCHES ".*clang-7")
  set(COMPILER_FAMILY "clang")
  set(COMPILER_VERSION "3.7.0svn")

# clang on Mac OS X, XCode 8.
elseif("${COMPILER_VERSION_FULL}" MATCHES ".*clang-8")
  set(COMPILER_FAMILY "clang")
  set(COMPILER_VERSION "3.8.0svn")

# clang on Mac OS X, XCode 9.
#
# TODO(dan): 4.0.0svn is just a guess, because Apple has not (as of the time of
# writing) released the sources [1]. [2] and [3] are good resources for
# determining the upstream Clang version as well.
#
# [1]: https://opensource.apple.com/
# [2]: https://gist.github.com/yamaya/2924292
# [3]: https://gist.github.com/epipping/ef8b02b0cfaec4a5ebf3a57092145a3f
elseif("${COMPILER_VERSION_FULL}" MATCHES ".*clang-9")
  set(COMPILER_FAMILY "clang")
  set(COMPILER_VERSION "4.0.0svn")

# clang on macOS, XCode 10.
#
# TODO(wdberkeley): 6.0.0svn is also just a guess, for the same reason, and
# generated from the same sources, particularly the comment
# https://gist.github.com/yamaya/2924292#gistcomment-801888.
elseif("${COMPILER_VERSION_FULL}" MATCHES ".*clang-10")
  set(COMPILER_FAMILY "clang")
  set(COMPILER_VERSION "6.0.0svn")

# gcc
elseif("${COMPILER_VERSION_FULL}" MATCHES ".*gcc version.*")
  set(COMPILER_FAMILY "gcc")
  string(REGEX REPLACE ".*gcc version ([0-9\\.]+).*" "\\1"
    COMPILER_VERSION "${COMPILER_VERSION_FULL}")
else()
  message(FATAL_ERROR "Unknown compiler. Version info:\n${COMPILER_VERSION_FULL}")
endif()

message("Selected compiler ${COMPILER_FAMILY} ${COMPILER_VERSION}")

# gcc (and some varieties of clang) mention the path prefix where system headers
# and libraries are located.
if("${COMPILER_VERSION_FULL}" MATCHES "Configured with: .* --prefix=([^ ]*)")
  set(COMPILER_SYSTEM_PREFIX_PATH ${CMAKE_MATCH_1})
  message("Selected compiler built with --prefix=${COMPILER_SYSTEM_PREFIX_PATH}")
endif()