#

# Copyright (c) 2011, 2019, Oracle and/or its affiliates. All rights reserved.

# DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

#

# This code is free software; you can redistribute it and/or modify it

# under the terms of the GNU General Public License version 2 only, as

# published by the Free Software Foundation.  Oracle designates this

# particular file as subject to the "Classpath" exception as provided

# by Oracle in the LICENSE file that accompanied this code.

#

# This code is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

# version 2 for more details (a copy is included in the LICENSE file that

# accompanied this code).

#

# You should have received a copy of the GNU General Public License version

# 2 along with this work; if not, write to the Free Software Foundation,

# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

#

# Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

# or visit www.oracle.com if you need additional information or have any

# questions.

#

########################################################################

# This file is responsible for detecting, verifying and setting up the

# toolchain, i.e. the compiler, linker and related utilities. It will setup

# proper paths to the binaries, but it will not setup any flags.

#

# The binaries used is determined by the toolchain type, which is the family of

# compilers and related tools that are used.

########################################################################

# All valid toolchains, regardless of platform (used by help.m4)

VALID_TOOLCHAINS_all="gcc clang solstudio xlc microsoft"

# These toolchains are valid on different platforms

VALID_TOOLCHAINS_linux="gcc clang"

VALID_TOOLCHAINS_solaris="solstudio"

VALID_TOOLCHAINS_macosx="gcc clang"

VALID_TOOLCHAINS_aix="xlc"

VALID_TOOLCHAINS_windows="microsoft"

# Toolchain descriptions

TOOLCHAIN_DESCRIPTION_clang="clang/LLVM"

TOOLCHAIN_DESCRIPTION_gcc="GNU Compiler Collection"

TOOLCHAIN_DESCRIPTION_microsoft="Microsoft Visual Studio"

TOOLCHAIN_DESCRIPTION_solstudio="Oracle Solaris Studio"

TOOLCHAIN_DESCRIPTION_xlc="IBM XL C/C++"

# Minimum supported versions, empty means unspecified

TOOLCHAIN_MINIMUM_VERSION_clang="3.2"

TOOLCHAIN_MINIMUM_VERSION_gcc="4.8"

TOOLCHAIN_MINIMUM_VERSION_microsoft="16.00.30319.01" # VS2010

TOOLCHAIN_MINIMUM_VERSION_solstudio="5.13"

TOOLCHAIN_MINIMUM_VERSION_xlc=""

# Minimum supported linker versions, empty means unspecified

TOOLCHAIN_MINIMUM_LD_VERSION_gcc="2.18"

# Prepare the system so that TOOLCHAIN_CHECK_COMPILER_VERSION can be called.

# Must have CC_VERSION_NUMBER and CXX_VERSION_NUMBER.

# $1 - optional variable prefix for compiler and version variables (BUILD_)

# $2 - optional variable prefix for comparable variable (OPENJDK_BUILD_)

AC_DEFUN([TOOLCHAIN_PREPARE_FOR_VERSION_COMPARISONS],

[

  if test "x[$]$1CC_VERSION_NUMBER" != "x[$]$1CXX_VERSION_NUMBER"; then

    AC_MSG_WARN([C and C++ compiler have different version numbers, [$]$1CC_VERSION_NUMBER vs [$]$1CXX_VERSION_NUMBER.])

    AC_MSG_WARN([This typically indicates a broken setup, and is not supported])

  fi

  # We only check CC_VERSION_NUMBER since we assume CXX_VERSION_NUMBER is equal.

  if [ [[ "[$]$1CC_VERSION_NUMBER" =~ (.*\.){4} ]] ]; then

    AC_MSG_WARN([C compiler version number has more than four parts (W.X.Y.Z): [$]$1CC_VERSION_NUMBER. Comparisons might be wrong.])

  fi

  if [ [[  "[$]$1CC_VERSION_NUMBER" =~ [0-9]{6} ]] ]; then

    AC_MSG_WARN([C compiler version number has a part larger than 99999: [$]$1CC_VERSION_NUMBER. Comparisons might be wrong.])

  fi

  $2COMPARABLE_ACTUAL_VERSION=`$AWK -F. '{ printf("%05d%05d%05d%05d\n", [$]1, [$]2, [$]3, [$]4) }' <<< "[$]$1CC_VERSION_NUMBER"`

])

# Check if the configured compiler (C and C++) is of a specific version or

# newer. TOOLCHAIN_PREPARE_FOR_VERSION_COMPARISONS must have been called before.

#

# Arguments:

#   VERSION:   The version string to check against the found version

#   IF_AT_LEAST:   block to run if the compiler is at least this version (>=)

#   IF_OLDER_THAN:   block to run if the compiler is older than this version (<)

#   PREFIX:   Optional variable prefix for compiler to compare version for (OPENJDK_BUILD_)

BASIC_DEFUN_NAMED([TOOLCHAIN_CHECK_COMPILER_VERSION],

    [*VERSION PREFIX IF_AT_LEAST IF_OLDER_THAN], [$@],

[

  # Need to assign to a variable since m4 is blocked from modifying parts in [].

  REFERENCE_VERSION=ARG_VERSION

  if [ [[ "$REFERENCE_VERSION" =~ (.*\.){4} ]] ]; then

    AC_MSG_ERROR([Internal error: Cannot compare to ARG_VERSION, only four parts (W.X.Y.Z) is supported])

  fi

  if [ [[ "$REFERENCE_VERSION" =~ [0-9]{6} ]] ]; then

    AC_MSG_ERROR([Internal error: Cannot compare to ARG_VERSION, only parts < 99999 is supported])

  fi

  # Version comparison method inspired by http://stackoverflow.com/a/24067243

  COMPARABLE_REFERENCE_VERSION=`$AWK -F. '{ printf("%05d%05d%05d%05d\n", [$]1, [$]2, [$]3, [$]4) }' <<< "$REFERENCE_VERSION"`

  if test [$]ARG_PREFIX[COMPARABLE_ACTUAL_VERSION] -ge $COMPARABLE_REFERENCE_VERSION ; then

    :

    ARG_IF_AT_LEAST

  else

    :

    ARG_IF_OLDER_THAN

  fi

])

# Prepare the system so that TOOLCHAIN_CHECK_COMPILER_VERSION can be called.

# Must have LD_VERSION_NUMBER.

# $1 - optional variable prefix for compiler and version variables (BUILD_)

# $2 - optional variable prefix for comparable variable (OPENJDK_BUILD_)

AC_DEFUN([TOOLCHAIN_PREPARE_FOR_LD_VERSION_COMPARISONS],

[

  if [ [[ "[$]$1LD_VERSION_NUMBER" =~ (.*\.){4} ]] ]; then

    AC_MSG_WARN([Linker version number has more than four parts (W.X.Y.Z): [$]$1LD_VERSION_NUMBER. Comparisons might be wrong.])

  fi

  if [ [[  "[$]$1LD_VERSION_NUMBER" =~ [0-9]{6} ]] ]; then

    AC_MSG_WARN([Linker version number has a part larger than 99999: [$]$1LD_VERSION_NUMBER. Comparisons might be wrong.])

  fi

  $2COMPARABLE_ACTUAL_LD_VERSION=`$AWK -F. '{ printf("%05d%05d%05d%05d\n", [$]1, [$]2, [$]3, [$]4) }' <<< "[$]$1LD_VERSION_NUMBER"`

])

# Check if the configured linker is of a specific version or

# newer. TOOLCHAIN_PREPARE_FOR_LD_VERSION_COMPARISONS must have been called before.

#

# Arguments:

#   VERSION:   The version string to check against the found version

#   IF_AT_LEAST:   block to run if the compiler is at least this version (>=)

#   IF_OLDER_THAN:   block to run if the compiler is older than this version (<)

#   PREFIX:   Optional variable prefix for compiler to compare version for (OPENJDK_BUILD_)

BASIC_DEFUN_NAMED([TOOLCHAIN_CHECK_LINKER_VERSION],

    [*VERSION PREFIX IF_AT_LEAST IF_OLDER_THAN], [$@],

[

  # Need to assign to a variable since m4 is blocked from modifying parts in [].

  REFERENCE_VERSION=ARG_VERSION

  if [ [[ "$REFERENCE_VERSION" =~ (.*\.){4} ]] ]; then

    AC_MSG_ERROR([Internal error: Cannot compare to ARG_VERSION, only four parts (W.X.Y.Z) is supported])

  fi

  if [ [[ "$REFERENCE_VERSION" =~ [0-9]{6} ]] ]; then

    AC_MSG_ERROR([Internal error: Cannot compare to ARG_VERSION, only parts < 99999 is supported])

  fi

  # Version comparison method inspired by http://stackoverflow.com/a/24067243

  COMPARABLE_REFERENCE_VERSION=`$AWK -F. '{ printf("%05d%05d%05d%05d\n", [$]1, [$]2, [$]3, [$]4) }' <<< "$REFERENCE_VERSION"`

  if test [$]ARG_PREFIX[COMPARABLE_ACTUAL_LD_VERSION] -ge $COMPARABLE_REFERENCE_VERSION ; then

    :

    ARG_IF_AT_LEAST

  else

    :

    ARG_IF_OLDER_THAN

  fi

])

# Setup a number of variables describing how native output files are

# named on this platform/toolchain.

AC_DEFUN([TOOLCHAIN_SETUP_FILENAME_PATTERNS],

[

  # Define filename patterns

  if test "x$OPENJDK_TARGET_OS" = xwindows; then

    LIBRARY_PREFIX=

    SHARED_LIBRARY_SUFFIX='.dll'

    STATIC_LIBRARY_SUFFIX='.lib'

    SHARED_LIBRARY='[$]1.dll'

    STATIC_LIBRARY='[$]1.lib'

    OBJ_SUFFIX='.obj'

  else

    LIBRARY_PREFIX=lib

    SHARED_LIBRARY_SUFFIX='.so'

    STATIC_LIBRARY_SUFFIX='.a'

    SHARED_LIBRARY='lib[$]1.so'

    STATIC_LIBRARY='lib[$]1.a'

    OBJ_SUFFIX='.o'

    if test "x$OPENJDK_TARGET_OS" = xmacosx; then

      # For full static builds, we're overloading the SHARED_LIBRARY

      # variables in order to limit the amount of changes required.

      # It would be better to remove SHARED and just use LIBRARY and

      # LIBRARY_SUFFIX for libraries that can be built either

      # shared or static and use STATIC_* for libraries that are

      # always built statically.

      if test "x$STATIC_BUILD" = xtrue; then

        SHARED_LIBRARY='lib[$]1.a'

        SHARED_LIBRARY_SUFFIX='.a'

      else

        SHARED_LIBRARY='lib[$]1.dylib'

        SHARED_LIBRARY_SUFFIX='.dylib'

      fi

    fi

  fi

  AC_SUBST(LIBRARY_PREFIX)

  AC_SUBST(SHARED_LIBRARY_SUFFIX)

  AC_SUBST(STATIC_LIBRARY_SUFFIX)

  AC_SUBST(SHARED_LIBRARY)

  AC_SUBST(STATIC_LIBRARY)

  AC_SUBST(OBJ_SUFFIX)

])

# Determine which toolchain type to use, and make sure it is valid for this

# platform. Setup various information about the selected toolchain.

AC_DEFUN_ONCE([TOOLCHAIN_DETERMINE_TOOLCHAIN_TYPE],

[

  AC_ARG_WITH(toolchain-type, [AS_HELP_STRING([--with-toolchain-type],

      [the toolchain type (or family) to use, use '--help' to show possible values @<:@platform dependent@:>@])])

  # Use indirect variable referencing

  toolchain_var_name=VALID_TOOLCHAINS_$OPENJDK_BUILD_OS

  VALID_TOOLCHAINS=${!toolchain_var_name}

  if test "x$OPENJDK_TARGET_OS" = xmacosx; then

    if test -n "$XCODEBUILD"; then

      # On Mac OS X, default toolchain to clang after Xcode 5

      XCODE_VERSION_OUTPUT=`"$XCODEBUILD" -version 2>&1 | $HEAD -n 1`

      $ECHO "$XCODE_VERSION_OUTPUT" | $GREP "Xcode " > /dev/null

      if test $? -ne 0; then

        AC_MSG_NOTICE([xcodebuild output: $XCODE_VERSION_OUTPUT])

        AC_MSG_ERROR([Failed to determine Xcode version.])

      fi

      XCODE_MAJOR_VERSION=`$ECHO $XCODE_VERSION_OUTPUT | \

          $SED -e 's/^Xcode \(@<:@1-9@:>@@<:@0-9.@:>@*\)/\1/' | \

          $CUT -f 1 -d .`

      AC_MSG_NOTICE([Xcode major version: $XCODE_MAJOR_VERSION])

      if test $XCODE_MAJOR_VERSION -ge 5; then

          DEFAULT_TOOLCHAIN="clang"

      else

          DEFAULT_TOOLCHAIN="gcc"

      fi

    else

      # If Xcode is not installed, but the command line tools are

      # then we can't run xcodebuild. On these systems we should

      # default to clang

      DEFAULT_TOOLCHAIN="clang"

    fi

  else

    # First toolchain type in the list is the default

    DEFAULT_TOOLCHAIN=${VALID_TOOLCHAINS%% *}

  fi

  if test "x$with_toolchain_type" = xlist; then

    # List all toolchains

    AC_MSG_NOTICE([The following toolchains are valid on this platform:])

    for toolchain in $VALID_TOOLCHAINS; do

      toolchain_var_name=TOOLCHAIN_DESCRIPTION_$toolchain

      TOOLCHAIN_DESCRIPTION=${!toolchain_var_name}

      $PRINTF "  %-10s  %s\n" $toolchain "$TOOLCHAIN_DESCRIPTION"

    done

    exit 0

  elif test "x$with_toolchain_type" != x; then

    # User override; check that it is valid

    if test "x${VALID_TOOLCHAINS/$with_toolchain_type/}" = "x${VALID_TOOLCHAINS}"; then

      AC_MSG_NOTICE([Toolchain type $with_toolchain_type is not valid on this platform.])

      AC_MSG_NOTICE([Valid toolchains: $VALID_TOOLCHAINS.])

      AC_MSG_ERROR([Cannot continue.])

    fi

    TOOLCHAIN_TYPE=$with_toolchain_type

  else

    # No flag given, use default

    TOOLCHAIN_TYPE=$DEFAULT_TOOLCHAIN

  fi

  AC_SUBST(TOOLCHAIN_TYPE)

  # on AIX, check for xlclang++ on the PATH and TOOLCHAIN_PATH and use it if it is available

  if test "x$OPENJDK_TARGET_OS" = xaix; then

    if test "x$TOOLCHAIN_PATH" != x; then

      XLC_TEST_PATH=${TOOLCHAIN_PATH}/

    fi

    XLCLANG_VERSION_OUTPUT=`${XLC_TEST_PATH}xlclang++ -qversion 2>&1 | $HEAD -n 1`

    $ECHO "$XLCLANG_VERSION_OUTPUT" | $GREP "IBM XL C/C++ for AIX" > /dev/null

    if test $? -eq 0; then

      AC_MSG_NOTICE([xlclang++ output: $XLCLANG_VERSION_OUTPUT])

    else

      AC_MSG_ERROR([xlclang++ version output check failed, output: $XLCLANG_VERSION_OUTPUT])

    fi

  fi

  TOOLCHAIN_CC_BINARY_clang="clang"

  TOOLCHAIN_CC_BINARY_gcc="gcc"

  TOOLCHAIN_CC_BINARY_microsoft="cl$EXE_SUFFIX"

  TOOLCHAIN_CC_BINARY_solstudio="cc"

  TOOLCHAIN_CC_BINARY_xlc="xlclang"

  TOOLCHAIN_CXX_BINARY_clang="clang++"

  TOOLCHAIN_CXX_BINARY_gcc="g++"

  TOOLCHAIN_CXX_BINARY_microsoft="cl$EXE_SUFFIX"

  TOOLCHAIN_CXX_BINARY_solstudio="CC"

  TOOLCHAIN_CXX_BINARY_xlc="xlclang++"

  # Use indirect variable referencing

  toolchain_var_name=TOOLCHAIN_DESCRIPTION_$TOOLCHAIN_TYPE

  TOOLCHAIN_DESCRIPTION=${!toolchain_var_name}

  toolchain_var_name=TOOLCHAIN_MINIMUM_VERSION_$TOOLCHAIN_TYPE

  TOOLCHAIN_MINIMUM_VERSION=${!toolchain_var_name}

  toolchain_var_name=TOOLCHAIN_MINIMUM_LD_VERSION_$TOOLCHAIN_TYPE

  TOOLCHAIN_MINIMUM_LD_VERSION=${!toolchain_var_name}

  toolchain_var_name=TOOLCHAIN_CC_BINARY_$TOOLCHAIN_TYPE

  TOOLCHAIN_CC_BINARY=${!toolchain_var_name}

  toolchain_var_name=TOOLCHAIN_CXX_BINARY_$TOOLCHAIN_TYPE

  TOOLCHAIN_CXX_BINARY=${!toolchain_var_name}

  TOOLCHAIN_SETUP_FILENAME_PATTERNS

  if test "x$TOOLCHAIN_TYPE" = "x$DEFAULT_TOOLCHAIN"; then

    AC_MSG_NOTICE([Using default toolchain $TOOLCHAIN_TYPE ($TOOLCHAIN_DESCRIPTION)])

  else

    AC_MSG_NOTICE([Using user selected toolchain $TOOLCHAIN_TYPE ($TOOLCHAIN_DESCRIPTION). Default toolchain is $DEFAULT_TOOLCHAIN.])

  fi

])

# Before we start detecting the toolchain executables, we might need some

# special setup, e.g. additional paths etc.

AC_DEFUN_ONCE([TOOLCHAIN_PRE_DETECTION],

[

  # FIXME: Is this needed?

  AC_LANG(C++)

  # Store the CFLAGS etc passed to the configure script.

  ORG_CFLAGS="$CFLAGS"

  ORG_CXXFLAGS="$CXXFLAGS"

  # autoconf magic only relies on PATH, so update it if tools dir is specified

  OLD_PATH="$PATH"

  # On Windows, we need to detect the visual studio installation first.

  # This will change the PATH, but we need to keep that new PATH even

  # after toolchain detection is done, since the compiler (on x86) uses

  # it for DLL resolution in runtime.

  if test "x$OPENJDK_BUILD_OS" = "xwindows" \

      && test "x$TOOLCHAIN_TYPE" = "xmicrosoft"; then

    TOOLCHAIN_SETUP_VISUAL_STUDIO_ENV

    if test "x$OPENJDK_BUILD_OS_ENV" = "xwindows.wsl"; then

      # Append VS_PATH. In WSL, VS_PATH will not contain the WSL env path needed

      # for using basic Unix tools, so need to keep the original PATH.

      BASIC_APPEND_TO_PATH(PATH, $VS_PATH)

      BASIC_APPEND_TO_PATH(WSLENV, "PATH/l:LIB:INCLUDE")

      export WSLENV

    else

      # Reset path to VS_PATH. It will include everything that was on PATH at the time we

      # ran TOOLCHAIN_SETUP_VISUAL_STUDIO_ENV.

      PATH="$VS_PATH"

    fi

    # The microsoft toolchain also requires INCLUDE and LIB to be set.

    export INCLUDE="$VS_INCLUDE"

    export LIB="$VS_LIB"

  else

    if test "x$XCODE_VERSION_OUTPUT" != x; then

      # For Xcode, we set the Xcode version as TOOLCHAIN_VERSION

      TOOLCHAIN_VERSION=`$ECHO $XCODE_VERSION_OUTPUT | $CUT -f 2 -d ' '`

      TOOLCHAIN_DESCRIPTION="$TOOLCHAIN_DESCRIPTION from Xcode $TOOLCHAIN_VERSION"

    else

      # Currently we do not define this for other toolchains. This might change as the need arise.

      TOOLCHAIN_VERSION=

    fi

  fi

  AC_SUBST(TOOLCHAIN_VERSION)

  # Finally add TOOLCHAIN_PATH at the beginning, to allow --with-tools-dir to

  # override all other locations.

  if test "x$TOOLCHAIN_PATH" != x; then

    PATH=$TOOLCHAIN_PATH:$PATH

  fi

])

# Restore path, etc

AC_DEFUN_ONCE([TOOLCHAIN_POST_DETECTION],

[

  # Restore old path, except for the microsoft toolchain, which requires VS_PATH

  # to remain in place. Otherwise the compiler will not work in some siutations

  # in later configure checks.

  if test "x$TOOLCHAIN_TYPE" != "xmicrosoft"; then

    PATH="$OLD_PATH"

  fi

  # Restore the flags to the user specified values.

  # This is necessary since AC_PROG_CC defaults CFLAGS to "-g -O2"

  CFLAGS="$ORG_CFLAGS"

  CXXFLAGS="$ORG_CXXFLAGS"

])

# Check if a compiler is of the toolchain type we expect, and save the version

# information from it. If the compiler does not match the expected type,

# this function will abort using AC_MSG_ERROR. If it matches, the version will

# be stored in CC_VERSION_NUMBER/CXX_VERSION_NUMBER (as a dotted number), and

# the full version string in CC_VERSION_STRING/CXX_VERSION_STRING.

#

# $1 = compiler to test (CC or CXX)

# $2 = human readable name of compiler (C or C++)

AC_DEFUN([TOOLCHAIN_EXTRACT_COMPILER_VERSION],

[

  COMPILER=[$]$1

  COMPILER_NAME=$2

  if test "x$TOOLCHAIN_TYPE" = xsolstudio; then

    # cc -V output typically looks like

    #     cc: Sun C 5.12 Linux_i386 2011/11/16

    # or

    #     cc: Studio 12.5 Sun C 5.14 SunOS_sparc 2016/05/31

    COMPILER_VERSION_OUTPUT=`$COMPILER -V 2>&1`

    # Check that this is likely to be the Solaris Studio cc.

    $ECHO "$COMPILER_VERSION_OUTPUT" | $GREP "^.* Sun $COMPILER_NAME" > /dev/null

    if test $? -ne 0; then

      ALT_VERSION_OUTPUT=`$COMPILER --version 2>&1`

      AC_MSG_NOTICE([The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler.])

      AC_MSG_NOTICE([The result from running with -V was: "$COMPILER_VERSION_OUTPUT"])

      AC_MSG_NOTICE([The result from running with --version was: "$ALT_VERSION_OUTPUT"])

      AC_MSG_ERROR([A $TOOLCHAIN_TYPE compiler is required. Try setting --with-tools-dir.])

    fi

    # Remove usage instructions (if present), and

    # collapse compiler output into a single line

    COMPILER_VERSION_STRING=`$ECHO $COMPILER_VERSION_OUTPUT | \

        $SED -e 's/ *@<:@Uu@:>@sage:.*//'`

    COMPILER_VERSION_NUMBER=`$ECHO $COMPILER_VERSION_OUTPUT | \

        $SED -e "s/^.*@<:@ ,\t@:>@$COMPILER_NAME@<:@ ,\t@:>@\(@<:@1-9@:>@\.@<:@0-9@:>@@<:@0-9@:>@*\).*/\1/"`

  elif test  "x$TOOLCHAIN_TYPE" = xxlc; then

    # xlc -qversion output typically looks like

    #     IBM XL C/C++ for AIX, V11.1 (5724-X13)

    #     Version: 11.01.0000.0015

    COMPILER_VERSION_OUTPUT=`$COMPILER -qversion 2>&1`

    # Check that this is likely to be the IBM XL C compiler.

    $ECHO "$COMPILER_VERSION_OUTPUT" | $GREP "IBM XL C" > /dev/null

    if test $? -ne 0; then

      ALT_VERSION_OUTPUT=`$COMPILER --version 2>&1`

      AC_MSG_NOTICE([The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler.])

      AC_MSG_NOTICE([The result from running with -qversion was: "$COMPILER_VERSION_OUTPUT"])

      AC_MSG_NOTICE([The result from running with --version was: "$ALT_VERSION_OUTPUT"])

      AC_MSG_ERROR([A $TOOLCHAIN_TYPE compiler is required. Try setting --with-tools-dir.])

    fi

    # Collapse compiler output into a single line

    COMPILER_VERSION_STRING=`$ECHO $COMPILER_VERSION_OUTPUT`

    COMPILER_VERSION_NUMBER=`$ECHO $COMPILER_VERSION_OUTPUT | \

        $SED -e 's/^.*, V\(@<:@1-9@:>@@<:@0-9.@:>@*\).*$/\1/'`

  elif test  "x$TOOLCHAIN_TYPE" = xmicrosoft; then

    # There is no specific version flag, but all output starts with a version string.

    # First line typically looks something like:

    # Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.40219.01 for 80x86

    COMPILER_VERSION_OUTPUT=`"$COMPILER" 2>&1 | $GREP -v 'ERROR.*UtilTranslatePathList' | $HEAD -n 1 | $TR -d '\r'`

    # Check that this is likely to be Microsoft CL.EXE.

    $ECHO "$COMPILER_VERSION_OUTPUT" | $GREP "Microsoft.*Compiler" > /dev/null

    if test $? -ne 0; then

      AC_MSG_NOTICE([The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler.])

      AC_MSG_NOTICE([The result from running it was: "$COMPILER_VERSION_OUTPUT"])

      AC_MSG_ERROR([A $TOOLCHAIN_TYPE compiler is required. Try setting --with-tools-dir.])

    fi

    # Collapse compiler output into a single line

    COMPILER_VERSION_STRING=`$ECHO $COMPILER_VERSION_OUTPUT`

    COMPILER_VERSION_NUMBER=`$ECHO $COMPILER_VERSION_OUTPUT | \

        $SED -e 's/^.*ersion.\(@<:@1-9@:>@@<:@0-9.@:>@*\) .*$/\1/'`

  elif test  "x$TOOLCHAIN_TYPE" = xgcc; then

    # gcc --version output typically looks like

    #     gcc (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1

    #     Copyright (C) 2013 Free Software Foundation, Inc.

    #     This is free software; see the source for copying conditions.  There is NO

    #     warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

    COMPILER_VERSION_OUTPUT=`$COMPILER --version 2>&1`

    # Check that this is likely to be GCC.

    $ECHO "$COMPILER_VERSION_OUTPUT" | $GREP "Free Software Foundation" > /dev/null

    if test $? -ne 0; then

      AC_MSG_NOTICE([The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler.])

      AC_MSG_NOTICE([The result from running with --version was: "$COMPILER_VERSION"])

      AC_MSG_ERROR([A $TOOLCHAIN_TYPE compiler is required. Try setting --with-tools-dir.])

    fi

    # Remove Copyright and legalese from version string, and

    # collapse into a single line

    COMPILER_VERSION_STRING=`$ECHO $COMPILER_VERSION_OUTPUT | \

        $SED -e 's/ *Copyright .*//'`

    COMPILER_VERSION_NUMBER=`$ECHO $COMPILER_VERSION_OUTPUT | \

  elif test  "x$TOOLCHAIN_TYPE" = xclang; then

    # clang --version output typically looks like

    #    Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)

    #    clang version 3.3 (tags/RELEASE_33/final)

    # or

    #    Debian clang version 3.2-7ubuntu1 (tags/RELEASE_32/final) (based on LLVM 3.2)