mongodb/SConstruct

# -*- mode: python; -*-
# build file for MongoDB
# this requires scons
# you can get from http://www.scons.org
# then just type scons

# some common tasks
#   build 64-bit mac and pushing to s3
#      scons --64 s3dist
#      scons --distname=0.8 s3dist
#      all s3 pushes require settings.py and simples3

# This file, SConstruct, configures the build environment, and then delegates to
# several, subordinate SConscript files, which describe specific build rules.

import buildscripts
import copy
import datetime
import imp
import os
import re
import shutil
import stat
import sys
import textwrap
import types
import urllib
import urllib2
import uuid
from buildscripts import utils
from buildscripts import moduleconfig

import libdeps

EnsureSConsVersion( 1, 1, 0 )

def findSettingsSetup():
    sys.path.append( "." )
    sys.path.append( ".." )
    sys.path.append( "../../" )

def versiontuple(v):
    return tuple(map(int, (v.split("."))))

# --- platform identification ---
#
# This needs to precede the options section so that we can only offer some options on certain
# platforms.

platform = os.sys.platform
nix = False
linux = False
darwin = False
windows = False
freebsd = False
openbsd = False
solaris = False

if "darwin" == platform:
    darwin = True
    platform = "osx" # prettier than darwin
elif platform.startswith("linux"):
    linux = True
    platform = "linux"
elif "sunos5" == platform:
    solaris = True
elif platform.startswith( "freebsd" ):
    freebsd = True
elif platform.startswith( "openbsd" ):
    openbsd = True
elif "win32" == platform:
    windows = True
else:
    print( "No special config for [" + platform + "] which probably means it won't work" )

nix = not windows

# --- options ----
use_clang = False

options = {}

def add_option( name, help, nargs, contributesToVariantDir,
                dest=None, default = None, type="string", choices=None, metavar=None, const=None ):

    if dest is None:
        dest = name

    if type == 'choice' and not metavar:
        metavar = '[' + '|'.join(choices) + ']'

    AddOption( "--" + name , 
               dest=dest,
               type=type,
               nargs=nargs,
               action="store",
               choices=choices,
               default=default,
               metavar=metavar,
               const=const,
               help=help )

    options[name] = { "help" : help ,
                      "nargs" : nargs ,
                      "contributesToVariantDir" : contributesToVariantDir ,
                      "dest" : dest,
                      "default": default }

def get_option( name ):
    return GetOption( name )

def has_option( name ):
    x = get_option( name )
    if x is None:
        return False

    if x == False:
        return False

    if x == "":
        return False

    return True

def use_system_version_of_library(name):
    return has_option('use-system-all') or has_option('use-system-' + name)

# Returns true if we have been configured to use a system version of any C++ library. If you
# add a new C++ library dependency that may be shimmed out to the system, add it to the below
# list.
def using_system_version_of_cxx_libraries():
    cxx_library_names = ["tcmalloc", "boost", "v8"]
    return True in [use_system_version_of_library(x) for x in cxx_library_names]

def get_variant_dir():

    build_dir = get_option('build-dir').rstrip('/')

    if has_option('variant-dir'):
        return (build_dir + '/' + get_option('variant-dir')).rstrip('/')

    substitute = lambda x: re.sub( "[:,\\\\/]" , "_" , x )

    a = []

    for name in options:
        o = options[name]
        if not has_option( o["dest"] ):
            continue
        if not o["contributesToVariantDir"]:
            continue
        if get_option(o["dest"]) == o["default"]:
            continue

        if o["nargs"] == 0:
            a.append( name )
        else:
            x = substitute( get_option( name ) )
            a.append( name + "_" + x )

    extras = []
    if has_option("extra-variant-dirs"):
        extras = [substitute(x) for x in get_option( 'extra-variant-dirs' ).split( ',' )]

    if has_option("add-branch-to-variant-dir"):
        extras += ["branch_" + substitute( utils.getGitBranch() )]

    if has_option('cache'):
        s = "cached"
        s += "/".join(extras) + "/"
    else:
        s = "${PYSYSPLATFORM}/"
        a += extras

        if len(a) > 0:
            a.sort()
            s += "/".join( a ) + "/"
        else:
            s += "normal/"

    return (build_dir + '/' + s).rstrip('/')

# build output
add_option( "mute" , "do not display commandlines for compiling and linking, to reduce screen noise", 0, False )

# installation/packaging
add_option( "prefix" , "installation prefix" , 1 , False, default='$BUILD_ROOT/install' )
add_option( "distname" , "dist name (0.8.0)" , 1 , False )
add_option( "distmod", "additional piece for full dist name" , 1 , False )
add_option( "distarch", "override the architecture name in dist output" , 1 , False )
add_option( "nostrip", "do not strip installed binaries" , 0 , False )
add_option( "extra-variant-dirs", "extra variant dir components, separated by commas", 1, False)
add_option( "add-branch-to-variant-dir", "add current git branch to the variant dir", 0, False )
add_option( "build-dir", "build output directory", 1, False, default='#build')
add_option( "variant-dir", "override variant subdirectory", 1, False )

# linking options
add_option( "release" , "release build" , 0 , True )
add_option( "static" , "fully static build" , 0 , False )
add_option( "static-libstdc++" , "statically link libstdc++" , 0 , False )
add_option( "lto", "enable link time optimizations (experimental, except with MSVC)" , 0 , True )
add_option( "dynamic-windows", "dynamically link on Windows", 0, True)

# base compile flags
add_option( "64" , "whether to force 64 bit" , 0 , True , "force64" )
add_option( "32" , "whether to force 32 bit" , 0 , True , "force32" )

add_option( "endian" , "endianness of target platform" , 1 , False , "endian",
            type="choice", choices=["big", "little", "auto"], default="auto" )

add_option( "cxx", "compiler to use" , 1 , True )
add_option( "cc", "compiler to use for c" , 1 , True )
add_option( "cc-use-shell-environment", "use $CC from shell for C compiler" , 0 , False )
add_option( "cxx-use-shell-environment", "use $CXX from shell for C++ compiler" , 0 , False )
add_option( "ld", "linker to use" , 1 , True )
add_option( "c++11", "enable c++11 support (experimental)", "?", True,
            type="choice", choices=["on", "off", "auto"], const="on", default="auto" )
add_option( "disable-minimum-compiler-version-enforcement",
            "allow use of unsupported older compilers (NEVER for production builds)",
            0, False )

add_option( "cpppath", "Include path if you have headers in a nonstandard directory" , 1 , False )
add_option( "libpath", "Library path if you have libraries in a nonstandard directory" , 1 , False )

add_option( "extrapath", "comma separated list of add'l paths  (--extrapath /opt/foo/,/foo) static linking" , 1 , False )
add_option( "extrapathdyn", "comma separated list of add'l paths  (--extrapath /opt/foo/,/foo) dynamic linking" , 1 , False )
add_option( "extralib", "comma separated list of libraries  (--extralib js_static,readline" , 1 , False )

add_option( "no-glibc-check" , "don't check for new versions of glibc" , 0 , False )

# experimental features
add_option( "mm", "use main memory instead of memory mapped files" , 0 , True )
add_option( "ssl" , "Enable SSL" , 0 , True )
add_option( "ssl-fips-capability", "Enable the ability to activate FIPS 140-2 mode", 0, True );
add_option( "rocksdb" , "Enable RocksDB" , 0 , False )
add_option( "wiredtiger", "Enable wiredtiger", "?", True, "wiredtiger",
            type="choice", choices=["on", "off"], const="on", default="on")

# library choices
js_engine_choices = ['v8-3.12', 'v8-3.25', 'none']
add_option( "js-engine", "JavaScript scripting engine implementation", 1, False,
           type='choice', default=js_engine_choices[0], choices=js_engine_choices)
add_option( "libc++", "use libc++ (experimental, requires clang)", 0, True )

add_option( "use-glibcxx-debug",
            "Enable the glibc++ debug implementations of the C++ standard libary", 0, True )

# mongo feature options
add_option( "noshell", "don't build shell" , 0 , True )
add_option( "safeshell", "don't let shell scripts run programs (still, don't run untrusted scripts)" , 0 , True )
add_option( "win2008plus",
            "use newer operating system API features (deprecated, use win-version-min instead)" ,
            0 , False )

# dev options
add_option( "d", "debug build no optimization, etc..." , 0 , True , "debugBuild" )
add_option( "dd", "debug build no optimization, additional debug logging, etc..." , 0 , True , "debugBuildAndLogging" )

# new style debug and optimize flags
add_option( "dbg", "Enable runtime debugging checks", "?", True, "dbg",
            type="choice", choices=["on", "off"], const="on" )

add_option( "opt", "Enable compile-time optimization", "?", True, "opt",
            type="choice", choices=["on", "off"], const="on" )

add_option( "sanitize", "enable selected sanitizers", 1, True, metavar="san1,san2,...sanN" )
add_option( "llvm-symbolizer", "name of (or path to) the LLVM symbolizer", 1, False, default="llvm-symbolizer" )

add_option( "durableDefaultOn" , "have durable default to on" , 0 , True )
add_option( "durableDefaultOff" , "have durable default to off" , 0 , True )

add_option( "pch" , "use precompiled headers to speed up the build (experimental)" , 0 , True , "usePCH" )
add_option( "distcc" , "use distcc for distributing builds" , 0 , False )

# debugging/profiling help
if os.sys.platform.startswith("linux"):
    defaultAllocator = 'tcmalloc'
else:
    defaultAllocator = 'system'
add_option( "allocator" , "allocator to use (tcmalloc or system)" , 1 , True,
            default=defaultAllocator )
add_option( "gdbserver" , "build in gdb server support" , 0 , True )
add_option( "heapcheck", "link to heap-checking malloc-lib and look for memory leaks during tests" , 0 , False )
add_option( "gcov" , "compile with flags for gcov" , 0 , True )

add_option("smokedbprefix", "prefix to dbpath et al. for smoke tests", 1 , False )
add_option("smokeauth", "run smoke tests with --auth", 0 , False )

add_option("use-sasl-client", "Support SASL authentication in the client library", 0, False)

add_option( "use-system-tcmalloc", "use system version of tcmalloc library", 0, True )

add_option( "use-system-pcre", "use system version of pcre library", 0, True )

add_option( "use-system-wiredtiger", "use system version of wiredtiger library", 0, True)

# library choices
boost_choices = ['1.49', '1.56']
add_option( "internal-boost", "Specify internal boost version to use", 1, True,
           type='choice', default=boost_choices[0], choices=boost_choices)

add_option( "use-system-boost", "use system version of boost libraries", 0, True )

add_option( "use-system-snappy", "use system version of snappy library", 0, True )

add_option( "use-system-zlib", "use system version of zlib library", 0, True )

add_option( "use-system-v8", "use system version of v8 library", 0, True )

add_option( "use-system-stemmer", "use system version of stemmer", 0, True )

add_option( "use-system-yaml", "use system version of yaml", 0, True )

add_option( "use-system-all" , "use all system libraries", 0 , True )

# deprecated
add_option( "use-new-tools" , "put new tools in the tarball", 0 , False )

add_option( "use-cpu-profiler",
            "Link against the google-perftools profiler library",
            0, False )

add_option('build-fast-and-loose', "looser dependency checking, ignored for --release builds",
           '?', False, type="choice", choices=["on", "off"], const="on", default="on")

add_option('disable-warnings-as-errors', "Don't add -Werror to compiler command line", 0, False)

add_option('propagate-shell-environment',
           "Pass shell environment to sub-processes (NEVER for production builds)",
           0, False)

if darwin:
    osx_version_choices = ['10.7', '10.8', '10.9', '10.10']
    add_option("osx-version-min", "minimum OS X version to support", 1, True,
               type = 'choice', default = osx_version_choices[0], choices = osx_version_choices)

elif windows:
    win_version_min_choices = {
        'xpsp3'   : ('0501', '0300'),
        'ws03sp2' : ('0502', '0200'),
        'vista'   : ('0600', '0000'),
        'ws08r2'  : ('0601', '0000'),
        'win7'    : ('0601', '0000'),
        'win8'    : ('0602', '0000'),
    }

    add_option("win-version-min", "minimum Windows version to support", 1, True,
               type = 'choice', default = None,
               choices = win_version_min_choices.keys())

    # Someday get rid of --32 and --64 for windows and use these with a --msvc-target-arch flag
    # that mirrors msvc-host-arch.
    msvc_arch_choices = ['x86', 'i386', 'amd64', 'emt64', 'x86_64', 'ia64']

    add_option("msvc-host-arch", "host architecture for ms toolchain", 1, True,
               type="choice", choices=msvc_arch_choices)

    add_option("msvc-script",
               "msvc toolchain setup script, pass no argument to suppress script execution",
               1, True)

    add_option("msvc-version", "select msvc version", 1, True)

add_option('cache',
           "Use an object cache rather than a per-build variant directory (experimental)",
           0, False)

add_option('cache-dir',
           "Specify the directory to use for caching objects if --cache is in use",
           1, False, default="$BUILD_ROOT/scons/cache")

# don't run configure if user calls --help
if GetOption('help'):
    Return()

# --- environment setup ---

# If the user isn't using the # to indicate top-of-tree or $ to expand a variable, forbid
# relative paths. Relative paths don't really work as expected, because they end up relative to
# the top level SConstruct, not the invokers CWD. We could in theory fix this with
# GetLaunchDir, but that seems a step too far.
buildDir = get_option('build-dir').rstrip('/')
if buildDir[0] not in ['$', '#']:
    if not os.path.isabs(buildDir):
        print("Do not use relative paths with --build-dir")
        Exit(1)

cacheDir = get_option('cache-dir').rstrip('/')
if cacheDir[0] not in ['$', '#']:
    if not os.path.isabs(cachdDIr):
        print("Do not use relative paths with --cache-dir")
        Exit(1)

installDir = get_option('prefix').rstrip('/')
if installDir[0] not in ['$', '#']:
    if not os.path.isabs(installDir):
        print("Do not use relative paths with --prefix")
        Exit(1)

sconsDataDir = Dir(buildDir).Dir('scons')
SConsignFile(str(sconsDataDir.File('sconsign')))

def printLocalInfo():
    import sys, SCons
    print( "scons version: " + SCons.__version__ )
    print( "python version: " + " ".join( [ `i` for i in sys.version_info ] ) )

printLocalInfo()

boostLibs = [ "thread" , "filesystem" , "program_options", "system" ]

onlyServer = len( COMMAND_LINE_TARGETS ) == 0 or ( len( COMMAND_LINE_TARGETS ) == 1 and str( COMMAND_LINE_TARGETS[0] ) in [ "mongod" , "mongos" , "test" ] )

linux64  = False
force32 = has_option( "force32" ) 
force64 = has_option( "force64" )
if not force64 and not force32 and os.getcwd().endswith( "mongo-64" ):
    force64 = True
    print( "*** assuming you want a 64-bit build b/c of directory *** " )
msarch = None
if force32:
    msarch = "x86"
elif force64:
    msarch = "amd64"

releaseBuild = has_option("release")

if has_option("debugBuild") or has_option("debugBuildAndLogging"):
    print("Error: the --d and --dd flags are no longer permitted; use --dbg and --opt instead")
    Exit(1)

dbg_opt_mapping = {
    # --dbg, --opt   :   dbg    opt
    ( None,  None  ) : ( False, True ),
    ( None,  "on"  ) : ( False, True ),
    ( None,  "off" ) : ( False, False ),
    ( "on",  None  ) : ( True,  False ),  # special case interaction
    ( "on",  "on"  ) : ( True,  True ),
    ( "on",  "off" ) : ( True,  False ),
    ( "off", None  ) : ( False, True ),
    ( "off", "on"  ) : ( False, True ),
    ( "off", "off" ) : ( False, False ),
}
debugBuild, optBuild = dbg_opt_mapping[(get_option('dbg'), get_option('opt'))]

if releaseBuild and (debugBuild or not optBuild):
    print("Error: A --release build may not have debugging, and must have optimization")
    Exit(1)

static = has_option( "static" )

noshell = has_option( "noshell" ) 

jsEngine = get_option( "js-engine")

usev8 = (jsEngine != 'none')

v8version = jsEngine[3:] if jsEngine.startswith('v8-') else 'none'
v8suffix = '' if v8version == '3.12' else '-' + v8version

usePCH = has_option( "usePCH" )

# We defer building the env until we have determined whether we want certain values. Some values
# in the env actually have semantics for 'None' that differ from being absent, so it is better
# to build it up via a dict, and then construct the Environment in one shot with kwargs.
#
# Yes, BUILD_ROOT vs BUILD_DIR is confusing. Ideally, BUILD_DIR would actually be called
# VARIANT_DIR, and at some point we should probably do that renaming. Until we do though, we
# also need an Environment variable for the argument to --build-dir, which is the parent of all
# variant dirs. For now, we call that BUILD_ROOT. If and when we s/BUILD_DIR/VARIANT_DIR/g,
# then also s/BUILD_ROOT/BUILD_DIR/g.
envDict = dict(BUILD_ROOT=buildDir,
               BUILD_DIR=get_variant_dir(),
               DIST_ARCHIVE_SUFFIX='.tgz',
               EXTRAPATH=get_option("extrapath"),
               MODULE_BANNERS=[],
               ARCHIVE_ADDITION_DIR_MAP={},
               ARCHIVE_ADDITIONS=[],
               PYTHON=utils.find_python(),
               SERVER_ARCHIVE='${SERVER_DIST_BASENAME}${DIST_ARCHIVE_SUFFIX}',
               tools=["default", "gch", "jsheader", "mergelib", "mongo_unittest", "textfile"],
               UNITTEST_ALIAS='unittests',
               # TODO: Move unittests.txt to $BUILD_DIR, but that requires
               # changes to MCI.
               UNITTEST_LIST='$BUILD_ROOT/unittests.txt',
               PYSYSPLATFORM=os.sys.platform,
               PCRE_VERSION='8.30',
               CONFIGUREDIR=sconsDataDir.Dir('sconf_temp'),
               CONFIGURELOG=sconsDataDir.File('config.log'),
               INSTALL_DIR=installDir,
               )

if windows:
    if msarch:
        envDict['TARGET_ARCH'] = msarch

    # We can't set this to None without disturbing the autodetection,
    # so only set it conditionally.
    if has_option('msvc-host-arch'):
        envDict['HOST_ARCH'] = get_option('msvc-host-arch')

    msvc_version = get_option('msvc-version')
    msvc_script = get_option('msvc-script')

    if msvc_version:
        if msvc_script:
            print("Passing --msvc-version with --msvc-script is not meaningful")
            Exit(1)
        envDict['MSVC_VERSION'] = msvc_version

    # The python None value is meaningful to MSVC_USE_SCRIPT; we want to interpret
    # --msvc-script= with no argument as meaning 'None', so check explicitly against None so
    # that '' is not interpreted as false.
    if msvc_script is not None:
        if has_option('msvc-host-arch'):
            print("Passing --msvc-host-arch with --msvc-script is not meaningful")
            Exit(1)
        if msarch:
            print("Passing --32 or --64 with --msvc-script is not meaningful")
            Exit(1)
        if msvc_script == "":
            msvc_script = None
        envDict['MSVC_USE_SCRIPT'] = msvc_script

env = Environment(**envDict)
del envDict

if has_option("cache"):
    EnsureSConsVersion( 2, 3, 0 )
    if has_option("release"):
        print("Using the experimental --cache option is not permitted for --release builds")
        Exit(1)
    if has_option("gcov"):
        print("Mixing --cache and --gcov doesn't work correctly yet. See SERVER-11084")
        Exit(1)
    env.CacheDir(str(env.Dir(cacheDir)))

# This could be 'if solaris', but unfortuantely that variable hasn't been set yet.
if "sunos5" == os.sys.platform:
    # SERVER-9890: On Solaris, SCons preferentially loads the sun linker tool 'sunlink' when
    # using the 'default' tools as we do above. The sunlink tool sets -G as the flag for
    # creating a shared library. But we don't want that, since we always drive our link step
    # through CC or CXX. Instead, we want to let the compiler map GCC's '-shared' flag to the
    # appropriate linker specs that it has compiled in. We could (and should in the future)
    # select an empty set of tools above and then enable them as appropriate on a per platform
    # basis. Until then the simplest solution, as discussed on the scons-users mailing list,
    # appears to be to simply explicitly run the 'gnulink' tool to overwrite the Environment
    # changes made by 'sunlink'. See the following thread for more detail:
    #  http://four.pairlist.net/pipermail/scons-users/2013-June/001486.html
    env.Tool('gnulink')

if optBuild:
    env.Append( CPPDEFINES=["MONGO_OPTIMIZED_BUILD"] )

if has_option("propagate-shell-environment"):
    env['ENV'] = dict(os.environ);

# Ignore requests to build fast and loose for release builds.
if get_option('build-fast-and-loose') == "on" and not has_option('release'):
    # See http://www.scons.org/wiki/GoFastButton for details
    env.Decider('MD5-timestamp')
    env.SetOption('max_drift', 1)

if has_option('mute'):
    env.Append( CCCOMSTR = "Compiling $TARGET" )
    env.Append( CXXCOMSTR = env["CCCOMSTR"] )
    env.Append( SHCCCOMSTR = "Compiling $TARGET" )
    env.Append( SHCXXCOMSTR = env["SHCCCOMSTR"] )
    env.Append( LINKCOMSTR = "Linking $TARGET" )
    env.Append( SHLINKCOMSTR = env["LINKCOMSTR"] )
    env.Append( ARCOMSTR = "Generating library $TARGET" )

endian = get_option( "endian" )

if endian == "auto":
    endian = sys.byteorder

if endian == "little":
    env.Append( CPPDEFINES=[("MONGO_BYTE_ORDER", "1234")] )
elif endian == "big":
    env.Append( CPPDEFINES=[("MONGO_BYTE_ORDER", "4321")] )

env['_LIBDEPS'] = '$_LIBDEPS_OBJS'

if env['_LIBDEPS'] == '$_LIBDEPS_OBJS':
    # The libraries we build in LIBDEPS_OBJS mode are just placeholders for tracking dependencies.
    # This avoids wasting time and disk IO on them.
    def write_uuid_to_file(env, target, source):
        with open(env.File(target[0]).abspath, 'w') as fake_lib:
            fake_lib.write(str(uuid.uuid4()))
            fake_lib.write('\n')

    def noop_action(env, target, source):
        pass

    env['ARCOM'] = write_uuid_to_file
    env['ARCOMSTR'] = 'Generating placeholder library $TARGET'
    env['RANLIBCOM'] = noop_action
    env['RANLIBCOMSTR'] = 'Skipping ranlib for $TARGET'

libdeps.setup_environment( env )

if env['PYSYSPLATFORM'] == 'linux3':
    env['PYSYSPLATFORM'] = 'linux2'
if 'freebsd' in env['PYSYSPLATFORM']:
    env['PYSYSPLATFORM'] = 'freebsd'

if os.sys.platform == 'win32':
    env['OS_FAMILY'] = 'win'
else:
    env['OS_FAMILY'] = 'posix'

if has_option( "cc-use-shell-environment" ) and has_option( "cc" ):
    print("Cannot specify both --cc-use-shell-environment and --cc")
    Exit(1)
elif has_option( "cxx-use-shell-environment" ) and has_option( "cxx" ):
    print("Cannot specify both --cxx-use-shell-environment and --cxx")
    Exit(1)

if has_option( "cxx-use-shell-environment" ):
    env["CXX"] = os.getenv("CXX");
    env["CC"] = env["CXX"]
if has_option( "cc-use-shell-environment" ):
    env["CC"] = os.getenv("CC");

if has_option( "cxx" ):
    env["CC"] = get_option( "cxx" )
    env["CXX"] = get_option( "cxx" )
if has_option( "cc" ):
    env["CC"] = get_option( "cc" )

if has_option( "ld" ):
    env["LINK"] = get_option( "ld" )

if env['PYSYSPLATFORM'] in ('linux2', 'freebsd'):
    env['LINK_LIBGROUP_START'] = '-Wl,--start-group'
    env['LINK_LIBGROUP_END'] = '-Wl,--end-group'
    env['RELOBJ_LIBDEPS_START'] = '--whole-archive'
    env['RELOBJ_LIBDEPS_END'] = '--no-whole-archive'
    env['RELOBJ_LIBDEPS_ITEM'] = ''
elif env['PYSYSPLATFORM'] == 'darwin':
    env['RELOBJFLAGS'] = [ '-arch', '$PROCESSOR_ARCHITECTURE' ]
    env['LINK_LIBGROUP_START'] = ''
    env['LINK_LIBGROUP_END'] = ''
    env['RELOBJ_LIBDEPS_START'] = '-all_load'
    env['RELOBJ_LIBDEPS_END'] = ''
    env['RELOBJ_LIBDEPS_ITEM'] = ''
elif env['PYSYSPLATFORM'].startswith('sunos'):
    if force64:
        env['RELOBJFLAGS'] = ['-64']
    env['LINK_LIBGROUP_START'] = '-z rescan'
    env['LINK_LIBGROUP_END'] = ''
    env['RELOBJ_LIBDEPS_START'] = '-z allextract'
    env['RELOBJ_LIBDEPS_END'] = '-z defaultextract'
    env['RELOBJ_LIBDEPS_ITEM'] = ''

env["LIBPATH"] = []

if has_option( "libpath" ):
    env["LIBPATH"] = [get_option( "libpath" )]

if has_option( "cpppath" ):
    env["CPPPATH"] = [get_option( "cpppath" )]

env.Prepend( CPPDEFINES=[ "_SCONS" , 
                          "MONGO_EXPOSE_MACROS" ,
                          "SUPPORT_UTF8" ],  # for pcre
)

if has_option( "safeshell" ):
    env.Append( CPPDEFINES=[ "MONGO_SAFE_SHELL" ] )

if has_option( "durableDefaultOn" ):
    env.Append( CPPDEFINES=[ "_DURABLEDEFAULTON" ] )

if has_option( "durableDefaultOff" ):
    env.Append( CPPDEFINES=[ "_DURABLEDEFAULTOFF" ] )

extraLibPlaces = []

env['EXTRACPPPATH'] = []
env['EXTRALIBPATH'] = []
env['EXTRABINPATH'] = []

def addExtraLibs( s ):
    for x in s.split(","):
        env.Append( EXTRABINPATH=[ x + "/bin" ] )
        env.Append( EXTRACPPPATH=[ x + "/include" ] )
        env.Append( EXTRALIBPATH=[ x + "/lib" ] )
        env.Append( EXTRALIBPATH=[ x + "/lib64" ] )
        extraLibPlaces.append( x + "/lib" )

if has_option( "extrapath" ):
    addExtraLibs( GetOption( "extrapath" ) )

if has_option( "extrapathdyn" ):
    addExtraLibs( GetOption( "extrapathdyn" ) )

if has_option( "extralib" ):
    for x in GetOption( "extralib" ).split( "," ):
        env.Append( LIBS=[ x ] )

# ---- other build setup -----

if "uname" in dir(os):
    processor = os.uname()[4]
else:
    processor = "i386"

if force32:
    processor = "i386"
if force64:
    processor = "x86_64"

env['PROCESSOR_ARCHITECTURE'] = processor

nixLibPrefix = "lib"

dontReplacePackage = False
isBuildingLatest = False

def filterExists(paths):
    return filter(os.path.exists, paths)

if darwin:
    pass
elif linux:

    env.Append( LIBS=['m'] )

    if os.uname()[4] == "x86_64" and not force32:
        linux64 = True
        nixLibPrefix = "lib64"
        env.Append( EXTRALIBPATH=["/usr/lib64" , "/lib64" ] )
        env.Append( LIBS=["pthread"] )

        force64 = False

    if force32:
        env.Append( EXTRALIBPATH=["/usr/lib32"] )

    if static:
        env.Append( LINKFLAGS=" -static " )

elif solaris:
     env.Append( CPPDEFINES=[ "__sunos__" ] )
     env.Append( LIBS=["socket","resolv","lgrp"] )

elif freebsd:
    env.Append( LIBS=[ "kvm" ] )
    env.Append( EXTRACPPPATH=[ "/usr/local/include" ] )
    env.Append( EXTRALIBPATH=[ "/usr/local/lib" ] )
    env.Append( CPPDEFINES=[ "__freebsd__" ] )
    env.Append( CCFLAGS=[ "-fno-omit-frame-pointer" ] )

elif openbsd:
    env.Append( EXTRACPPPATH=[ "/usr/local/include" ] )
    env.Append( EXTRALIBPATH=[ "/usr/local/lib" ] )
    env.Append( CPPDEFINES=[ "__openbsd__" ] )
    env.Append( LIBS=[ "kvm" ] )

elif windows:
    dynamicCRT = has_option("dynamic-windows")

    env['DIST_ARCHIVE_SUFFIX'] = '.zip'

    if has_option('win-version-min') and has_option('win2008plus'):
        print("Can't specify both 'win-version-min' and 'win2008plus'")
        Exit(1)

    # If tools configuration fails to set up 'cl' in the path, fall back to importing the whole
    # shell environment and hope for the best. This will work, for instance, if you have loaded
    # an SDK shell.
    for pathdir in env['ENV']['PATH'].split(os.pathsep):
        if os.path.exists(os.path.join(pathdir, 'cl.exe')):
            break
    else:
        print("NOTE: Tool configuration did not find 'cl' compiler, falling back to os environment")
        env['ENV'] = dict(os.environ)

    env.Append( CPPDEFINES=[ "_UNICODE" ] )
    env.Append( CPPDEFINES=[ "UNICODE" ] )

    # /EHsc exception handling style for visual studio
    # /W3 warning level
    env.Append(CCFLAGS=["/EHsc","/W3"])

    # some warnings we don't like:
    # c4355
    # 'this' : used in base member initializer list
    #    The this pointer is valid only within nonstatic member functions. It cannot be used in the initializer list for a base class.
    # c4800
    # 'type' : forcing value to bool 'true' or 'false' (performance warning)
    #    This warning is generated when a value that is not bool is assigned or coerced into type bool. 
    # c4267
    # 'var' : conversion from 'size_t' to 'type', possible loss of data
    # When compiling with /Wp64, or when compiling on a 64-bit operating system, type is 32 bits but size_t is 64 bits when compiling for 64-bit targets. To fix this warning, use size_t instead of a type.
    # c4244
    # 'conversion' conversion from 'type1' to 'type2', possible loss of data
    #  An integer type is converted to a smaller integer type.
    # c4290
    #  C++ exception specification ignored except to indicate a function is not __declspec(nothrow
    #  A function is declared using exception specification, which Visual C++ accepts but does not
    #  implement
    # c4068
    #  unknown pragma -- added so that we can specify unknown pragmas for other compilers
    # c4351
    #  on extremely old versions of MSVC (pre 2k5), default constructing an array member in a
    #  constructor's initialization list would not zero the array members "in some cases".
    #  since we don't target MSVC versions that old, this warning is safe to ignore.
    env.Append( CCFLAGS=["/wd4355", "/wd4800", "/wd4267", "/wd4244",
                         "/wd4290", "/wd4068", "/wd4351"] )

    # some warnings we should treat as errors:
    # c4099
    #  identifier' : type name first seen using 'objecttype1' now seen using 'objecttype2'
    #    This warning occurs when classes and structs are declared with a mix of struct and class
    #    which can cause linker failures
    env.Append( CCFLAGS=["/we4099"] )

    env.Append( CPPDEFINES=["_CONSOLE","_CRT_SECURE_NO_WARNINGS"] )

    # this would be for pre-compiled headers, could play with it later  
    #env.Append( CCFLAGS=['/Yu"pch.h"'] )

    # docs say don't use /FD from command line (minimal rebuild)
    # /Gy function level linking (implicit when using /Z7)
    # /Z7 debug info goes into each individual .obj file -- no .pdb created 
    env.Append( CCFLAGS= ["/Z7", "/errorReport:none"] )

    # /DEBUG will tell the linker to create a .pdb file
    # which WinDbg and Visual Studio will use to resolve
    # symbols if you want to debug a release-mode image.
    # Note that this means we can't do parallel links in the build.
    #
    # Please also note that this has nothing to do with _DEBUG or optimization.
    env.Append( LINKFLAGS=["/DEBUG"] )

    # /MD:  use the multithreaded, DLL version of the run-time library (MSVCRT.lib/MSVCR###.DLL)
    # /MT:  use the multithreaded, static version of the run-time library (LIBCMT.lib)
    # /MDd: Defines _DEBUG, _MT, _DLL, and uses MSVCRTD.lib/MSVCRD###.DLL
    # /MTd: Defines _DEBUG, _MT, and causes your application to use the
    #       debug multithread version of the run-time library (LIBCMTD.lib)

    winRuntimeLibMap = {
          #dyn   #dbg
        ( False, False ) : "/MT",
        ( False, True  ) : "/MTd",
        ( True,  False ) : "/MD",
        ( True,  True  ) : "/MDd",
    }

    env.Append(CCFLAGS=[winRuntimeLibMap[(dynamicCRT, debugBuild)]])

    # With VS 2012 and later we need to specify 5.01 as the target console
    # so that our 32-bit builds run on Windows XP
    # See https://software.intel.com/en-us/articles/linking-applications-using-visual-studio-2012-to-run-on-windows-xp
    #
    if msarch == "x86":
        env.Append( LINKFLAGS=["/SUBSYSTEM:CONSOLE,5.01"])

    if optBuild:
        # /O2:  optimize for speed (as opposed to size)
        # /Oy-: disable frame pointer optimization (overrides /O2, only affects 32-bit)
        # /INCREMENTAL: NO - disable incremental link - avoid the level of indirection for function
        # calls
        env.Append( CCFLAGS=["/O2", "/Oy-"] )
        env.Append( LINKFLAGS=["/INCREMENTAL:NO"])
    else:
        env.Append( CCFLAGS=["/Od"] )

    if debugBuild and not optBuild:
        # /RTC1: - Enable Stack Frame Run-Time Error Checking; Reports when a variable is used
        # without having been initialized (implies /Od: no optimizations)
        env.Append( CCFLAGS=["/RTC1"] )

    # This gives 32-bit programs 4 GB of user address space in WOW64, ignored in 64-bit builds
    env.Append( LINKFLAGS=["/LARGEADDRESSAWARE"] )

    env.Append(LIBS=['ws2_32.lib',
                     'kernel32.lib',
                     'advapi32.lib',
                     'Psapi.lib',
                     'DbgHelp.lib',
                     'shell32.lib',
                     'Iphlpapi.lib'])

    # v8 calls timeGetTime()
    if usev8:
        env.Append(LIBS=['winmm.lib'])

    env.Append( EXTRACPPPATH=["#/../winpcap/Include"] )
    env.Append( EXTRALIBPATH=["#/../winpcap/Lib"] )

env['STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME'] = 1
if nix:

    if has_option( "static-libstdc++" ):
        env.Append( LINKFLAGS=["-static-libstdc++", "-static-libgcc"] )

    if has_option( "distcc" ):
        env["CXX"] = "distcc " + env["CXX"]

    # -Winvalid-pch Warn if a precompiled header (see Precompiled Headers) is found in the search path but can't be used.
    env.Append( CCFLAGS=["-fPIC",
                         "-fno-strict-aliasing",
                         "-ggdb",
                         "-pthread",
                         "-Wall",
                         "-Wsign-compare",
                         "-Wno-unknown-pragmas",
                         "-Winvalid-pch"] )
    # env.Append( " -Wconversion" ) TODO: this doesn't really work yet
    if linux or darwin:
        env.Append( CCFLAGS=["-pipe"] )
        if not has_option("disable-warnings-as-errors"):
            env.Append( CCFLAGS=["-Werror"] )

    env.Append( CPPDEFINES=["_FILE_OFFSET_BITS=64"] )
    env.Append( CXXFLAGS=["-Wnon-virtual-dtor", "-Woverloaded-virtual"] )
    env.Append( LINKFLAGS=["-fPIC", "-pthread"] )

    # SERVER-9761: Ensure early detection of missing symbols in dependent libraries at program
    # startup.
    #
    # TODO: Is it necessary to add to both linkflags and shlinkflags, or are LINKFLAGS
    # propagated to SHLINKFLAGS?
    if darwin:
        env.Append( LINKFLAGS=["-Wl,-bind_at_load"] )
        env.Append( SHLINKFLAGS=["-Wl,-bind_at_load"] )
    else:
        env.Append( LINKFLAGS=["-Wl,-z,now"] )
        env.Append( SHLINKFLAGS=["-Wl,-z,now"] )

    if not darwin:
        env.Append( LINKFLAGS=["-rdynamic"] )

    env.Append( LIBS=[] )

    #make scons colorgcc friendly
    for key in ('HOME', 'TERM'):
        try:
            env['ENV'][key] = os.environ[key]
        except KeyError:
            pass

    if linux and has_option( "gcov" ):
        env.Append( CXXFLAGS=" -fprofile-arcs -ftest-coverage " )
        env.Append( CPPDEFINES=["MONGO_GCOV"] )
        env.Append( LINKFLAGS=" -fprofile-arcs -ftest-coverage " )

    if optBuild:
        env.Append( CCFLAGS=["-O3"] )
    else:
        env.Append( CCFLAGS=["-O0"] )

    if debugBuild:
        if not optBuild:
            env.Append( CCFLAGS=["-fstack-protector"] )
            env.Append( LINKFLAGS=["-fstack-protector"] )
            env.Append( SHLINKFLAGS=["-fstack-protector"] )
        env['ENV']['GLIBCXX_FORCE_NEW'] = 1; # play nice with valgrind
        env.Append( CPPDEFINES=["_DEBUG"] );

    if force64:
        env.Append( CCFLAGS="-m64" )
        env.Append( LINKFLAGS="-m64" )

    if force32:
        env.Append( CCFLAGS="-m32" )
        env.Append( LINKFLAGS="-m32" )

    if has_option( "gdbserver" ):
        env.Append( CPPDEFINES=["USE_GDBSERVER"] )

if "uname" in dir(os):
    hacks = buildscripts.findHacks( os.uname() )
    if hacks is not None:
        hacks.insert( env , { "linux64" : linux64 } )

if has_option( "ssl" ):
    env.Append( CPPDEFINES=["MONGO_SSL"] )
    env.Append( MONGO_CRYPTO=["openssl"] )
    if windows:
        env.Append( LIBS=["libeay32"] )
        env.Append( LIBS=["ssleay32"] )
    else:
        env.Append( LIBS=["ssl"] )
        env.Append( LIBS=["crypto"] )
    if has_option("ssl-fips-capability"):
        env.Append( CPPDEFINES=["MONGO_SSL_FIPS"] )
else:
    env.Append( MONGO_CRYPTO=["tom"] )

wiredtiger = (get_option('wiredtiger') == 'on')

try:
    umask = os.umask(022)
except OSError:
    pass

if not windows:
    for keysuffix in [ "1" , "2" ]:
        keyfile = "jstests/libs/key%s" % keysuffix
        os.chmod( keyfile , stat.S_IWUSR|stat.S_IRUSR )

boostSuffix = "";
if not use_system_version_of_library("boost"):
    if get_option( "internal-boost") != "1.49":
        boostSuffix = "-1.56.0"
    env.Prepend(CPPDEFINES=['BOOST_ALL_NO_LIB'])

env.Append( CPPPATH=['$EXTRACPPPATH'],
            LIBPATH=['$EXTRALIBPATH'] )

# discover modules, and load the (python) module for each module's build.py
mongo_modules = moduleconfig.discover_modules('src/mongo/db/modules')
env['MONGO_MODULES'] = [m.name for m in mongo_modules]

# --- check system ---

def doConfigure(myenv):
    global wiredtiger

    # Check that the compilers work.
    #
    # TODO: Currently, we have some flags already injected. Eventually, this should test the
    # bare compilers, and we should re-check at the very end that TryCompile and TryLink still
    # work with the flags we have selected.
    conf = Configure(myenv, help=False)

    if 'CheckCXX' in dir( conf ):
        if not conf.CheckCXX():
            print("C++ compiler %s does not work" % (conf.env["CXX"]))
            Exit(1)

    # Only do C checks if CC != CXX
    check_c = (myenv["CC"] != myenv["CXX"])

    if check_c and 'CheckCC' in dir( conf ):
        if not conf.CheckCC():
            print("C compiler %s does not work" % (conf.env["CC"]))
            Exit(1)
    myenv = conf.Finish()

    # Identify the toolchain in use. We currently support the following:
    # TODO: Goes in the env?
    toolchain_gcc = "GCC"
    toolchain_clang = "clang"
    toolchain_msvc = "MSVC"

    def CheckForToolchain(context, toolchain, lang_name, compiler_var, source_suffix):
        test_bodies = {
            toolchain_gcc : (
                # Clang also defines __GNUC__
                """
                #if !defined(__GNUC__) || defined(__clang__)
                #error
                #endif
                """),
            toolchain_clang : (
                """
                #if !defined(__clang__)
                #error
                #endif
                """),
            toolchain_msvc : (
                """
                #if !defined(_MSC_VER)
                #error
                #endif
                """),
        }
        print_tuple = (lang_name, context.env[compiler_var], toolchain)
        context.Message('Checking if %s compiler "%s" is %s... ' % print_tuple)
        # Strip indentation from the test body to ensure that the newline at the end of the
        # endif is the last character in the file (rather than a line of spaces with no
        # newline), and that all of the preprocessor directives start at column zero. Both of
        # these issues can trip up older toolchains.
        test_body = textwrap.dedent(test_bodies[toolchain])
        result = context.TryCompile(test_body, source_suffix)
        context.Result(result)
        return result

    conf = Configure(myenv, help=False, custom_tests = {
        'CheckForToolchain' : CheckForToolchain,
    })

    toolchain = None
    have_toolchain = lambda: toolchain != None
    using_msvc = lambda: toolchain == toolchain_msvc
    using_gcc = lambda: toolchain == toolchain_gcc
    using_clang = lambda: toolchain == toolchain_clang

    if windows:
        toolchain_search_sequence = [toolchain_msvc]
    else:
        toolchain_search_sequence = [toolchain_gcc, toolchain_clang]

    for candidate_toolchain in toolchain_search_sequence:
        if conf.CheckForToolchain(candidate_toolchain, "C++", "CXX", ".cpp"):
            toolchain = candidate_toolchain
            break

    if not have_toolchain():
        print("Couldn't identify the toolchain")
        Exit(1)

    if check_c and not conf.CheckForToolchain(toolchain, "C", "CC", ".c"):
        print("C toolchain doesn't match identified C++ toolchain")
        Exit(1)

    myenv = conf.Finish()

    if using_msvc():
        compiler_minimum_string = "Microsoft Visual Studio 2013 Update 2"
        compiler_test_body = textwrap.dedent(
        """
        #if !defined(_MSC_VER)
        #error
        #endif

        #if _MSC_VER < 1800 || (_MSC_VER == 1800 && _MSC_FULL_VER < 180030501)
        #error %s or newer is required to build MongoDB
        #endif

        int main(int argc, char* argv[]) {
            return 0;
        }
        """ % compiler_minimum_string)
    elif using_gcc():
        # TODO: Really, we want GCC 4.8.2 here, but we are admitting 4.8.1
        # until our Solaris toolchain solution reaches 4.8.2. When our Solaris
        # toolchain reaches 4.8.2, upgrade this string, and the check below.
        compiler_minimum_string = "GCC 4.8.1"
        compiler_test_body = textwrap.dedent(
        """
        #if !defined(__GNUC__) || defined(__clang__)
        #error
        #endif

        #if (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 8) || (__GNUC__ == 4 && __GNUC_MINOR__ == 8 && __GNUC_PATCHLEVEL__ < 1)
        #error %s or newer is required to build MongoDB
        #endif

        int main(int argc, char* argv[]) {
            return 0;
        }
        """ % compiler_minimum_string)
    elif using_clang:
        compiler_minimum_string = "clang 3.4 (or Apple XCode 5.1.1)"
        compiler_test_body = textwrap.dedent(
        """
        #if !defined(__clang__)
        #error
        #endif

        #if defined(__apple_build_version__)
        #if __apple_build_version__ < 5030040
        #error %s or newer is required to build MongoDB
        #endif
        #elif (__clang_major__ < 3) || (__clang_major__ == 3 && __clang_minor__ < 4)
        #error %s or newer is required to build MongoDB
        #endif

        int main(int argc, char* argv[]) {
            return 0;
        }
        """ % (compiler_minimum_string, compiler_minimum_string))
    else:
        print("Error: can't check compiler minimum; don't know this compiler...")
        Exit(1)

    def CheckForMinimumCompiler(context, language):
        extension_for = {
            "C" : ".c",
            "C++" : ".cpp",
        }
        context.Message("Checking if %s compiler is %s or newer..." %
                        (language, compiler_minimum_string))
        result = context.TryCompile(compiler_test_body, extension_for[language])
        context.Result(result)
        return result;

    conf = Configure(myenv, help=False, custom_tests = {
        'CheckForMinimumCompiler' : CheckForMinimumCompiler,
    })

    c_compiler_validated = True
    if check_c:
        c_compiler_validated = conf.CheckForMinimumCompiler('C')
    cxx_compiler_validated = conf.CheckForMinimumCompiler('C++')

    myenv = conf.Finish();

    suppress_invalid = has_option("disable-minimum-compiler-version-enforcement")
    if releaseBuild and suppress_invalid:
        print("--disable-minimum-compiler-version-enforcement is forbidden with --release")
        Exit(1)

    if not (c_compiler_validated and cxx_compiler_validated):
        if not suppress_invalid:
            print("ERROR: Refusing to build with compiler that does not meet requirements")
            Exit(1)
        print("WARNING: Ignoring failed compiler version check per explicit user request.")
        print("WARNING: The build may fail, binaries may crash, or may run but corrupt data...")

    global use_clang
    use_clang = using_clang()

    # Figure out what our minimum windows version is. If the user has specified, then use
    # that. Otherwise, if they have explicitly selected between 32 bit or 64 bit, choose XP or
    # Vista respectively. Finally, if they haven't done either of these, try invoking the
    # compiler to figure out whether we are doing a 32 or 64 bit build and select as
    # appropriate.
    if windows:
        win_version_min = None
        default_32_bit_min = 'xpsp3'
        default_64_bit_min = 'ws03sp2'
        if has_option('win-version-min'):
            win_version_min = get_option('win-version-min')
        elif has_option('win2008plus'):
            win_version_min = 'win7'
        else:
            if force32:
                win_version_min = default_32_bit_min
            elif force64:
                win_version_min = default_64_bit_min
            else:
                def CheckFor64Bit(context):
                    win64_test_body = textwrap.dedent(
                        """
                        #if !defined(_WIN64)
                        #error
                        #endif
                        """
                    )
                    context.Message('Checking if toolchain is in 64-bit mode... ')
                    result = context.TryCompile(win64_test_body, ".c")
                    context.Result(result)
                    return result

                conf = Configure(myenv, help=False, custom_tests = {
                    'CheckFor64Bit' : CheckFor64Bit
                })
                if conf.CheckFor64Bit():
                    win_version_min = default_64_bit_min
                else:
                    win_version_min = default_32_bit_min
                conf.Finish();

        env['WIN_VERSION_MIN'] = win_version_min
        win_version_min = win_version_min_choices[win_version_min]
        env.Append( CPPDEFINES=[("_WIN32_WINNT", "0x" + win_version_min[0])] )
        env.Append( CPPDEFINES=[("NTDDI_VERSION", "0x" + win_version_min[0] + win_version_min[1])] )

    def CheckForx86(context):
        # See http://nadeausoftware.com/articles/2012/02/c_c_tip_how_detect_processor_type_using_compiler_predefined_macros
        test_body = """
        #if defined(__i386) || defined(_M_IX86)
        /* x86 32-bit */
        #else
        #error not 32-bit x86
        #endif
        """
        context.Message('Checking if target architecture is 32-bit x86...')
        ret = context.TryCompile(textwrap.dedent(test_body), ".c")
        context.Result(ret)
        return ret

    conf = Configure(myenv, help=False, custom_tests = {
        'CheckForx86' : CheckForx86,
    })

    if conf.CheckForx86():

        # If we are using GCC or clang to target 32 or x86, set the ISA minimum to 'nocona',
        # and the tuning to 'generic'. The choice of 'nocona' is selected because it
        #  -- includes MMX extenions which we need for tcmalloc on 32-bit
        #  -- can target 32 bit
        #  -- is at the time of this writing a widely-deployed 10 year old microarchitecture
        #  -- is available as a target architecture from GCC 4.0+
        # However, we only want to select an ISA, not the nocona specific scheduling, so we
        # select the generic tuning. For installations where hardware and system compiler rev are
        # contemporaries, the generic scheduling should be appropriate for a wide range of
        # deployed hardware.

        if using_gcc() or using_clang():
                myenv.Append( CCFLAGS=['-march=nocona', '-mtune=generic'] )

        # Wiredtiger only supports 64-bit architecture, and will fail to compile on 32-bit
        # so disable WiredTiger automatically on 32-bit since wiredtiger is on by default
        if wiredtiger == True:
            print "WARNING: WiredTiger is not supported on 32-bit platforms, disabling support"
            wiredtiger = False
    conf.Finish()

    # Enable PCH if we are on using gcc or clang and the 'Gch' tool is enabled. Otherwise,
    # remove any pre-compiled header since the compiler may try to use it if it exists.
    if usePCH and (using_gcc() or using_clang()):
        if 'Gch' in dir( myenv ):
            if using_clang():
                # clang++ uses pch.h.pch rather than pch.h.gch
                myenv['GCHSUFFIX'] = '.pch'
                # clang++ only uses pch from command line
                myenv.Prepend( CXXFLAGS=['-include pch.h'] )
            myenv['Gch'] = myenv.Gch( "$BUILD_DIR/mongo/pch.h$GCHSUFFIX",
                                        "src/mongo/pch.h" )[0]
            myenv['GchSh'] = myenv[ 'Gch' ]
    elif os.path.exists( myenv.File("$BUILD_DIR/mongo/pch.h$GCHSUFFIX").abspath ):
        print( "removing precompiled headers" )
        os.unlink( myenv.File("$BUILD_DIR/mongo/pch.h.$GCHSUFFIX").abspath )

    def AddFlagIfSupported(env, tool, extension, flag, **mutation):
        def CheckFlagTest(context, tool, extension, flag):
            test_body = ""
            context.Message('Checking if %s compiler supports %s... ' % (tool, flag))
            ret = context.TryCompile(test_body, extension)
            context.Result(ret)
            return ret

        if using_msvc():
            print("AddFlagIfSupported is not currently supported with MSVC")
            Exit(1)

        test_mutation = mutation
        if using_gcc():
            test_mutation = copy.deepcopy(mutation)
            # GCC helpfully doesn't issue a diagnostic on unknown flags of the form -Wno-xxx
            # unless other diagnostics are triggered. That makes it tough to check for support
            # for -Wno-xxx. To work around, if we see that we are testing for a flag of the
            # form -Wno-xxx (but not -Wno-error=xxx), we also add -Wxxx to the flags. GCC does
            # warn on unknown -Wxxx style flags, so this lets us probe for availablity of
            # -Wno-xxx.
            for kw in test_mutation.keys():
                test_flags = test_mutation[kw]
                for test_flag in test_flags:
                    if test_flag.startswith("-Wno-") and not test_flag.startswith("-Wno-error="):
                        test_flags.append(re.sub("^-Wno-", "-W", test_flag))

        cloned = env.Clone()
        cloned.Append(**test_mutation)

        # For GCC, we don't need anything since bad flags are already errors, but
        # adding -Werror won't hurt. For clang, bad flags are only warnings, so we need -Werror
        # to make them real errors.
        cloned.Append(CCFLAGS=['-Werror'])
        conf = Configure(cloned, help=False, custom_tests = {
                'CheckFlag' : lambda(ctx) : CheckFlagTest(ctx, tool, extension, flag)
        })
        available = conf.CheckFlag()
        conf.Finish()
        if available:
            env.Append(**mutation)
        return available

    def AddToCFLAGSIfSupported(env, flag):
        return AddFlagIfSupported(env, 'C', '.c', flag, CFLAGS=[flag])

    def AddToCCFLAGSIfSupported(env, flag):
        return AddFlagIfSupported(env, 'C', '.c', flag, CCFLAGS=[flag])

    def AddToCXXFLAGSIfSupported(env, flag):
        return AddFlagIfSupported(env, 'C++', '.cpp', flag, CXXFLAGS=[flag])

    if using_gcc() or using_clang():
        # This warning was added in g++-4.8.
        AddToCCFLAGSIfSupported(myenv, '-Wno-unused-local-typedefs')

        # Clang likes to warn about unused functions, which seems a tad aggressive and breaks
        # -Werror, which we want to be able to use.
        AddToCCFLAGSIfSupported(myenv, '-Wno-unused-function')

        # TODO: Note that the following two flags are added to CCFLAGS even though they are
        # really C++ specific. We need to do this because SCons passes CXXFLAGS *before*
        # CCFLAGS, but CCFLAGS contains -Wall, which re-enables the warnings we are trying to
        # suppress. In the future, we should move all warning flags to CCWARNFLAGS and
        # CXXWARNFLAGS and add these to CCOM and CXXCOM as appropriate.
        #
        # Clang likes to warn about unused private fields, but some of our third_party
        # libraries have such things.
        AddToCCFLAGSIfSupported(myenv, '-Wno-unused-private-field')

        # Prevents warning about using deprecated features (such as auto_ptr in c++11)
        # Using -Wno-error=deprecated-declarations does not seem to work on some compilers,
        # including at least g++-4.6.
        AddToCCFLAGSIfSupported(myenv, "-Wno-deprecated-declarations")

        # As of clang-3.4, this warning appears in v8, and gets escalated to an error.
        AddToCCFLAGSIfSupported(myenv, "-Wno-tautological-constant-out-of-range-compare")

        # New in clang-3.4, trips up things mostly in third_party, but in a few places in the
        # primary mongo sources as well.
        AddToCCFLAGSIfSupported(myenv, "-Wno-unused-const-variable")

        # Prevents warning about unused but set variables found in boost version 1.49
        # in boost/date_time/format_date_parser.hpp which does not work for compilers
        # GCC >= 4.6. Error explained in https://svn.boost.org/trac/boost/ticket/6136 .
        AddToCCFLAGSIfSupported(myenv, "-Wno-unused-but-set-variable")

    # Check if we need to disable null-conversion warnings
    if using_clang():
        def CheckNullConversion(context):

            test_body = """
            #include <boost/shared_ptr.hpp>
            struct TestType { int value; bool boolValue; };
            bool foo() {
                boost::shared_ptr<TestType> sp(new TestType);
                return NULL != sp;
            }
            """

            context.Message('Checking if implicit boost::shared_ptr null conversion is supported... ')
            ret = context.TryCompile(textwrap.dedent(test_body), ".cpp")
            context.Result(ret)
            return ret

        conf = Configure(myenv, help=False, custom_tests = {
            'CheckNullConversion' : CheckNullConversion,
        })
        if conf.CheckNullConversion() == False:
            env.Append( CCFLAGS="-Wno-null-conversion" )
        conf.Finish()

    # This needs to happen before we check for libc++, since it affects whether libc++ is available.
    if darwin and has_option('osx-version-min'):
        min_version = get_option('osx-version-min')
        min_version_flag = '-mmacosx-version-min=%s' % (min_version)
        if not AddToCCFLAGSIfSupported(myenv, min_version_flag):
            print( "Can't set minimum OS X version with this compiler" )
            Exit(1)
        myenv.AppendUnique(LINKFLAGS=[min_version_flag])

    usingLibStdCxx = False
    if has_option('libc++'):
        if not using_clang():
            print( 'libc++ is currently only supported for clang')
            Exit(1)
        if darwin and has_option('osx-version-min') and versiontuple(min_version) < versiontuple('10.7'):
            print("Warning: You passed option 'libc++'. You probably want to also pass 'osx-version-min=10.7' or higher for libc++ support.")
        if AddToCXXFLAGSIfSupported(myenv, '-stdlib=libc++'):
            myenv.Append(LINKFLAGS=['-stdlib=libc++'])
        else:
            print( 'libc++ requested, but compiler does not support -stdlib=libc++' )
            Exit(1)
    else:
        def CheckLibStdCxx(context):
            test_body = """
            #include <vector>
            #if !defined(__GLIBCXX__)
            #error
            #endif
            """

            context.Message('Checking if we are using libstdc++... ')
            ret = context.TryCompile(textwrap.dedent(test_body), ".cpp")
            context.Result(ret)
            return ret

        conf = Configure(myenv, help=False, custom_tests = {
            'CheckLibStdCxx' : CheckLibStdCxx,
        })
        usingLibStdCxx = conf.CheckLibStdCxx()
        conf.Finish()

    # Check to see if we are trying to use an elderly libstdc++, which we arbitrarily define as
    # 4.6.0. This is primarly to help people using clang in C++11 mode on OS X but forgetting
    # to use --libc++. We also use it to decide if we trust the libstdc++ debug mode. We would,
    # ideally, check the __GLIBCXX__ version, but for various reasons this is not
    # workable. Instead, we switch on the fact that _GLIBCXX_BEGIN_NAMESPACE_VERSION wasn't
    # introduced until libstdc++ 4.6.0.

    haveGoodLibStdCxx = False
    if usingLibStdCxx:

        def CheckModernLibStdCxx(context):

            test_body = """
            #include <vector>
            #if !defined(_GLIBCXX_BEGIN_NAMESPACE_VERSION)
            #error libstdcxx older than 4.6.0
            #endif
            """

            context.Message('Checking for libstdc++ 4.6.0 or better... ')
            ret = context.TryCompile(textwrap.dedent(test_body), ".cpp")
            context.Result(ret)
            return ret

        conf = Configure(myenv, help=False, custom_tests = {
            'CheckModernLibStdCxx' : CheckModernLibStdCxx,
        })
        haveGoodLibStdCxx = conf.CheckModernLibStdCxx()
        conf.Finish()

    # Sort out whether we can and should use C++11:
    cxx11_mode = get_option("c++11")

    if using_msvc():
        if cxx11_mode == "off":
            print( 'WARNING: Cannot disable C++11 features when using MSVC' )
    else:

        # In C++11 'auto' mode, don't use C++11 if we are linking against any system C++ libs.
        if cxx11_mode == "auto" and using_system_version_of_cxx_libraries():
            cxx11_mode = "off"

        # If we are using libstdc++, only allow C++11 mode with our line-in-the-sand good
        # libstdc++. As always, if in auto mode fall back to disabling if we don't have a good
        # libstdc++, otherwise fail the build because we can't honor the explicit request.
        if cxx11_mode != "off" and usingLibStdCxx:
            if not haveGoodLibStdCxx:
                if cxx11_mode == "auto":
                    cxx11_mode = "off"
                else:
                    print( 'Detected libstdc++ is too old to support C++11 mode' )
                    if darwin:
                        print( 'Try building with --libc++ and --osx-version-min=10.7 or higher' )
                    Exit(1)

        # We are going to be adding flags to the environment, but we don't want to persist
        # those changes unless we pass all the below checks. Make a copy of the environment
        # that we will modify, we will only "commit" the changes to the env if we pass all the
        # checks.
        cxx11Env = myenv.Clone()

        # For our other compilers (gcc and clang) we need to pass -std=c++0x or -std=c++11,
        # but we prefer the latter. Try that first, and fall back to c++0x if we don't
        # detect that --std=c++11 works. If we can't find a flag and C++11 was explicitly
        # requested, error out, otherwise turn off C++11 support in auto mode.
        if cxx11_mode != "off":
            if not AddToCXXFLAGSIfSupported(cxx11Env, '-std=c++11'):
                if not AddToCXXFLAGSIfSupported(cxx11Env, '-std=c++0x'):
                    if cxx11_mode == "auto":
                        cxx11_mode = "off"
                    else:
                        print( 'C++11 mode requested, but cannot find a flag to enable it' )
                        Exit(1)

        # We appear to have C++11, or at least a flag to enable it, which is now set in the
        # environment. If we are in auto mode, check if the compiler claims that it strictly
        # supports C++11, and disable C++11 if not. If the user has explicitly requested C++11,
        # we don't care about what the compiler claims to support, trust the user.
        if cxx11_mode == "auto":
            def CheckCxx11Official(context):
                test_body = """
                #if __cplusplus < 201103L
                #error
                #endif
                const int not_an_empty_file = 0;
                """

                context.Message('Checking if __cplusplus >= 201103L to auto-enable C++11... ')
                ret = context.TryCompile(textwrap.dedent(test_body), ".cpp")
                context.Result(ret)
                return ret

            conf = Configure(cxx11Env, help=False, custom_tests = {
                'CheckCxx11Official' : CheckCxx11Official,
            })

            if cxx11_mode == "auto" and not conf.CheckCxx11Official():
                cxx11_mode = "off"

            conf.Finish()

        # We require c99 mode for C files when C++11 is enabled, so perform the same dance
        # as above: if C++11 mode is not off, try the flag, if we are in auto mode and we fail
        # then turn off C++11, otherwise C++11 was explicitly requested and we should error out.
        if cxx11_mode != "off":
            if not AddToCFLAGSIfSupported(cxx11Env, '-std=c99'):
                if cxx11_mode == "auto":
                    cxx11_mode = "off"
                else:
                    print( "C++11 mode selected for C++ files, but can't enable C99 for C files" )
                    Exit(1)

        # If we got here and cxx11_mode hasn't become false, then its true, so swap in the
        # modified environment.
        if cxx11_mode != "off":
            cxx11_mode = "on"
            myenv = cxx11Env

    # rocksdb requires C++11 mode
    if has_option("rocksdb") and cxx11_mode == "off":
        print("--rocksdb requires C++11 mode to be enabled");
        Exit(1)

    if has_option("use-glibcxx-debug"):
        # If we are using a modern libstdc++ and this is a debug build and we control all C++
        # dependencies, then turn on the debugging features in libstdc++.
        if not debugBuild:
            print("--use-glibcxx-debug requires --dbg=on")
            Exit(1)
        if not usingLibStdCxx or not haveGoodLibStdCxx:
            print("--use-glibcxx-debug is only compatible with the GNU implementation of the "
                  "C++ standard libary, and requires minimum version 4.6")
            Exit(1)
        if using_system_version_of_cxx_libraries():
            print("--use-glibcxx-debug not compatible with system versions of C++ libraries.")
            Exit(1)
        myenv.Append(CPPDEFINES=["_GLIBCXX_DEBUG"]);

    # Check if we are on a POSIX system by testing if _POSIX_VERSION is defined.
    def CheckPosixSystem(context):

        test_body = """
        // POSIX requires the existence of unistd.h, so if we can't include unistd.h, we
        // are definitely not a POSIX system.
        #include <unistd.h>
        #if !defined(_POSIX_VERSION)
        #error not a POSIX system
        #endif
        """

        context.Message('Checking if we are on a POSIX system... ')
        ret = context.TryCompile(textwrap.dedent(test_body), ".c")
        context.Result(ret)
        return ret

    conf = Configure(myenv, help=False, custom_tests = {
        'CheckPosixSystem' : CheckPosixSystem,
    })
    posix_system = conf.CheckPosixSystem()
    conf.Finish()

    # Check if we are on a system that support the POSIX clock_gettime function
    #  and the "monotonic" clock.
    posix_monotonic_clock = False
    if posix_system:
        def CheckPosixMonotonicClock(context):

            test_body = """
            #include <unistd.h>
            #if !(defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0)
            #error POSIX clock_gettime not supported
            #elif !(defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0)
            #error POSIX monotonic clock not supported
            #endif
            """

            context.Message('Checking if the POSIX monotonic clock is supported... ')
            ret = context.TryCompile(textwrap.dedent(test_body), ".c")
            context.Result(ret)
            return ret

        conf = Configure(myenv, help=False, custom_tests = {
            'CheckPosixMonotonicClock' : CheckPosixMonotonicClock,
        })
        posix_monotonic_clock = conf.CheckPosixMonotonicClock()
        conf.Finish()

    if has_option('sanitize'):

        if not (using_clang() or using_gcc()):
            print( 'sanitize is only supported with clang or gcc')
            Exit(1)

        sanitizer_list = get_option('sanitize').split(',')

        using_lsan = 'leak' in sanitizer_list
        using_asan = 'address' in sanitizer_list or using_lsan

        if using_asan:
            if get_option('allocator') == 'tcmalloc':
                print("Cannot use address or leak sanitizer with tcmalloc")
                Exit(1)

        # If the user asked for leak sanitizer turn on the detect_leaks
        # ASAN_OPTION. If they asked for address sanitizer as well, drop
        # 'leak', because -fsanitize=leak means no address.
        #
        # --sanitize=leak:           -fsanitize=leak, detect_leaks=1
        # --sanitize=address,leak:   -fsanitize=address, detect_leaks=1
        # --sanitize=address:        -fsanitize=address
        #
        if using_lsan:
            if using_asan:
                myenv['ENV']['ASAN_OPTIONS'] = "detect_leaks=1"
            myenv['ENV']['LSAN_OPTIONS'] = "suppressions=%s" % myenv.File("#etc/lsan.suppressions").abspath
            if 'address' in sanitizer_list:
                sanitizer_list.remove('leak')

        sanitizer_option = '-fsanitize=' + ','.join(sanitizer_list)

        if AddToCCFLAGSIfSupported(myenv, sanitizer_option):
            myenv.Append(LINKFLAGS=[sanitizer_option])
            myenv.Append(CCFLAGS=['-fno-omit-frame-pointer'])
        else:
            print( 'Failed to enable sanitizers with flag: ' + sanitizer_option )
            Exit(1)

        blackfiles_map = {
            "address" : myenv.File("#etc/asan.blacklist"),
            "leak" : myenv.File("#etc/asan.blacklist"),
            "thread" : myenv.File("#etc/tsan.blacklist"),
            "undefined" : myenv.File("#etc/ubsan.blacklist"),
        }

        blackfiles = set([v for (k, v) in blackfiles_map.iteritems() if k in sanitizer_list])
        blacklist_options=["-fsanitize-blacklist=%s" % blackfile for blackfile in blackfiles]

        for blacklist_option in blacklist_options:
            if AddToCCFLAGSIfSupported(myenv, blacklist_option):
                myenv.Append(LINKFLAGS=[blacklist_option])

        llvm_symbolizer = get_option('llvm-symbolizer')
        if os.path.isabs(llvm_symbolizer):
            if not myenv.File(llvm_symbolizer).exists():
                print("WARNING: Specified symbolizer '%s' not found" % llvm_symbolizer)
                llvm_symbolizer = None
        else:
            llvm_symbolizer = myenv.WhereIs(llvm_symbolizer)

        if llvm_symbolizer:
            myenv['ENV']['ASAN_SYMBOLIZER_PATH'] = llvm_symbolizer
            myenv['ENV']['LSAN_SYMBOLIZER_PATH'] = llvm_symbolizer
        elif using_lsan:
            print("Using the leak sanitizer requires a valid symbolizer")
            Exit(1)

    if using_msvc():
        # http://blogs.msdn.com/b/vcblog/archive/2013/09/11/introducing-gw-compiler-switch.aspx
        #
        myenv.Append( CCFLAGS=["/Gw", "/Gy"] )
        myenv.Append( LINKFLAGS=["/OPT:REF"])

        # http://blogs.msdn.com/b/vcblog/archive/2014/03/25/linker-enhancements-in-visual-studio-2013-update-2-ctp2.aspx
        #
        myenv.Append( CCFLAGS=["/Zc:inline"])

    # Apply any link time optimization settings as selected by the 'lto' option.
    if has_option('lto'):
        if using_msvc():
            # Note that this is actually more aggressive than LTO, it is whole program
            # optimization due to /GL. However, this is historically what we have done for
            # windows, so we are keeping it.
            #
            # /GL implies /LTCG, so no need to say it in CCFLAGS, but we do need /LTCG on the
            # link flags.
            myenv.Append(CCFLAGS=['/GL'])
            myenv.Append(LINKFLAGS=['/LTCG'])
            myenv.Append(ARFLAGS=['/LTCG'])
        elif using_gcc() or using_clang():
            # For GCC and clang, the flag is -flto, and we need to pass it both on the compile
            # and link lines.
            if AddToCCFLAGSIfSupported(myenv, '-flto'):
                myenv.Append(LINKFLAGS=['-flto'])
            else:
                print( "Link time optimization requested, " +
                       "but selected compiler does not honor -flto" )
                Exit(1)
        else:
            printf("Don't know how to enable --lto on current toolchain")
            Exit(1)

    # glibc's memcmp is faster than gcc's
    if linux:
        AddToCCFLAGSIfSupported(myenv, "-fno-builtin-memcmp")

    # When using msvc, check for support for __declspec(thread), unless we have been asked
    # explicitly not to use it. For other compilers, see if __thread works.
    if using_msvc():
        haveDeclSpecThread = False
        def CheckDeclspecThread(context):
            test_body = """
            __declspec( thread ) int tsp_int;
            int main(int argc, char* argv[]) {
            tsp_int = argc;
            return 0;
            }
            """
            context.Message('Checking for __declspec(thread)... ')
            ret = context.TryLink(textwrap.dedent(test_body), ".cpp")
            context.Result(ret)
            return ret
        conf = Configure(myenv, help=False, custom_tests = {
            'CheckDeclspecThread' : CheckDeclspecThread,
        })
        haveDeclSpecThread = conf.CheckDeclspecThread()
        conf.Finish()
        if haveDeclSpecThread:
            myenv.Append(CPPDEFINES=['MONGO_HAVE___DECLSPEC_THREAD'])
    else:
        def CheckUUThread(context):
            test_body = """
            __thread int tsp_int;
            int main(int argc, char* argv[]) {
                tsp_int = argc;
                return 0;
            }
            """
            context.Message('Checking for __thread... ')
            ret = context.TryLink(textwrap.dedent(test_body), ".cpp")
            context.Result(ret)
            return ret
        conf = Configure(myenv, help=False, custom_tests = {
            'CheckUUThread' : CheckUUThread,
        })
        haveUUThread = conf.CheckUUThread()
        conf.Finish()
        if haveUUThread:
            myenv.Append(CPPDEFINES=['MONGO_HAVE___THREAD'])

    def CheckCXX11Atomics(context):
        test_body = """
        #include <atomic>
        int main(int argc, char **argv) {
            std::atomic<int> a(0);
            return a.fetch_add(1);
        }
        """
        context.Message('Checking for C++11 <atomic> support... ')
        ret = context.TryLink(textwrap.dedent(test_body), '.cpp')
        context.Result(ret)
        return ret;

    def CheckGCCAtomicBuiltins(context):
        test_body = """
        int main(int argc, char **argv) {
            int a = 0;
            int b = 0;
            int c = 0;

            __atomic_compare_exchange(&a, &b, &c, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
            return 0;
        }
        """
        context.Message('Checking for gcc __atomic builtins... ')
        ret = context.TryLink(textwrap.dedent(test_body), '.cpp')
        context.Result(ret)
        return ret

    def CheckGCCSyncBuiltins(context):
        test_body = """
        int main(int argc, char **argv) {
            int a = 0;
            return __sync_fetch_and_add(&a, 1);
        }

        //
        // Figure out if we are using gcc older than 4.2 to target 32-bit x86. If so, error out
        // even if we were able to compile the __sync statement, due to
        // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40693
        //
        #if defined(__i386__)
        #if !defined(__clang__)
        #if defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 2)
        #error "Refusing to use __sync in 32-bit mode with gcc older than 4.2"
        #endif
        #endif
        #endif
        """

        context.Message('Checking for useable __sync builtins... ')
        ret = context.TryLink(textwrap.dedent(test_body), '.cpp')
        context.Result(ret)
        return ret

    # not all C++11-enabled gcc versions have type properties
    def CheckCXX11IsTriviallyCopyable(context):
        test_body = """
        #include <type_traits>
        int main(int argc, char **argv) {
            class Trivial {
                int trivial1;
                double trivial2;
                struct {
                    float trivial3;
                    short trivial4;
                } trivial_member;
            };

            class NotTrivial {
                int x, y;
                NotTrivial(const NotTrivial& o) : x(o.y), y(o.x) {}
            };

            static_assert(std::is_trivially_copyable<Trivial>::value,
                          "I should be trivially copyable");
            static_assert(!std::is_trivially_copyable<NotTrivial>::value,
                          "I should not be trivially copyable");
            return 0;
        }
        """
        context.Message('Checking for C++11 is_trivially_copyable support... ')
        ret = context.TryCompile(textwrap.dedent(test_body), '.cpp')
        context.Result(ret)
        return ret

    conf = Configure(myenv, help=False, custom_tests = {
        'CheckCXX11Atomics': CheckCXX11Atomics,
        'CheckGCCAtomicBuiltins': CheckGCCAtomicBuiltins,
        'CheckGCCSyncBuiltins': CheckGCCSyncBuiltins,
        'CheckCXX11IsTriviallyCopyable': CheckCXX11IsTriviallyCopyable,
    })

    # Figure out what atomics mode to use by way of the tests defined above.
    #
    # Non_windows: <atomic> > __atomic > __sync
    # Windows: <atomic> > Interlocked functions / intrinsics.
    #
    # If we are in C++11 mode, try to use <atomic>. This is unusual for us, as typically we
    # only use __cplusplus >= 201103L to decide if we want to enable a feature. We make a
    # special case for the atomics and use them on platforms that offer them even if they don't
    # advertise full conformance. For MSVC systems, if we don't have <atomic> then no more
    # checks are required. Otherwise, we are on a GCC/clang system, where we may have __atomic
    # or __sync, so try those in that order next.
    #
    # If we don't end up defining a MONGO_HAVE for the atomics, we will end up falling back to
    # the Microsoft Interlocked functions/intrinsics when using MSVC, or the gcc_intel
    # implementation of hand-rolled assembly if using gcc/clang.

    if (using_msvc() or (cxx11_mode == "on")) and conf.CheckCXX11Atomics():
        conf.env.Append(CPPDEFINES=['MONGO_HAVE_CXX11_ATOMICS'])
    elif using_gcc() or using_clang():
        # Prefer the __atomic builtins. If we don't have those, try for __sync. Otherwise
        # atomic_intrinsics.h will try to fall back to the hand-rolled assembly implementations
        # in atomic_intrinsics_gcc_intel for x86 platforms.
        if conf.CheckGCCAtomicBuiltins():
            conf.env.Append(CPPDEFINES=["MONGO_HAVE_GCC_ATOMIC_BUILTINS"])
        else:
            if conf.CheckGCCSyncBuiltins():
                conf.env.Append(CPPDEFINES=["MONGO_HAVE_GCC_SYNC_BUILTINS"])

    if (cxx11_mode == "on") and conf.CheckCXX11IsTriviallyCopyable():
        conf.env.Append(CPPDEFINES=['MONGO_HAVE_STD_IS_TRIVIALLY_COPYABLE'])

    myenv = conf.Finish()

    conf = Configure(myenv)
    libdeps.setup_conftests(conf)

    if use_system_version_of_library("pcre"):
        conf.FindSysLibDep("pcre", ["pcre"])
        conf.FindSysLibDep("pcrecpp", ["pcrecpp"])

    if use_system_version_of_library("snappy"):
        conf.FindSysLibDep("snappy", ["snappy"])

    if use_system_version_of_library("zlib"):
        conf.FindSysLibDep("zlib", ["zlib" if windows else "z"])

    if use_system_version_of_library("stemmer"):
        conf.FindSysLibDep("stemmer", ["stemmer"])

    if use_system_version_of_library("yaml"):
        conf.FindSysLibDep("yaml", ["yaml-cpp"])

    if wiredtiger and use_system_version_of_library("wiredtiger"):
        if not conf.CheckCXXHeader( "wiredtiger.h" ):
            print( "Cannot find wiredtiger headers" )
            Exit(1)
        conf.FindSysLibDep("wiredtiger", ["wiredtiger"])

    if use_system_version_of_library("boost"):
        if not conf.CheckCXXHeader( "boost/filesystem/operations.hpp" ):
            print( "can't find boost headers" )
            Exit(1)

        conf.env.Append(CPPDEFINES=[("BOOST_THREAD_VERSION", "2")])

        # Note that on Windows with using-system-boost builds, the following 
        # FindSysLibDep calls do nothing useful (but nothing problematic either)
        for b in boostLibs:
            boostlib = "boost_" + b
            conf.FindSysLibDep( boostlib, [ boostlib + "-mt", boostlib ], language='C++' )

    if posix_system:
        conf.env.Append(CPPDEFINES=['MONGO_HAVE_HEADER_UNISTD_H'])
        conf.CheckLib('rt')
        conf.CheckLib('dl')

    if posix_monotonic_clock:
        conf.env.Append(CPPDEFINES=['MONGO_HAVE_POSIX_MONOTONIC_CLOCK'])

    if (conf.CheckCXXHeader( "execinfo.h" ) and
        conf.CheckDeclaration('backtrace', includes='#include <execinfo.h>') and
        conf.CheckDeclaration('backtrace_symbols', includes='#include <execinfo.h>') and
        conf.CheckDeclaration('backtrace_symbols_fd', includes='#include <execinfo.h>')):

        conf.env.Append( CPPDEFINES=[ "MONGO_HAVE_EXECINFO_BACKTRACE" ] )

    conf.env["_HAVEPCAP"] = conf.CheckLib( ["pcap", "wpcap"], autoadd=False )

    if solaris:
        conf.CheckLib( "nsl" )

    if usev8 and use_system_version_of_library("v8"):
        if debugBuild:
            v8_lib_choices = ["v8_g", "v8"]
        else:
            v8_lib_choices = ["v8"]
        conf.FindSysLibDep( "v8", v8_lib_choices )

    conf.env['MONGO_BUILD_SASL_CLIENT'] = bool(has_option("use-sasl-client"))
    if conf.env['MONGO_BUILD_SASL_CLIENT'] and not conf.CheckLibWithHeader(
            "sasl2", 
            ["stddef.h","sasl/sasl.h"], 
            "C", 
            "sasl_version_info(0, 0, 0, 0, 0, 0);", 
            autoadd=False ):
        Exit(1)

    # requires ports devel/libexecinfo to be installed
    if freebsd or openbsd:
        if not conf.CheckLib("execinfo"):
            print("Cannot find libexecinfo, please install devel/libexecinfo.")
            Exit(1)

    # 'tcmalloc' needs to be the last library linked. Please, add new libraries before this 
    # point.
    if get_option('allocator') == 'tcmalloc':
        if use_system_version_of_library('tcmalloc'):
            conf.FindSysLibDep("tcmalloc", ["tcmalloc"])
        elif has_option("heapcheck"):
            print ("--heapcheck does not work with the tcmalloc embedded in the mongodb source "
                   "tree.  Use --use-system-tcmalloc.")
            Exit(1)
    elif get_option('allocator') == 'system':
        pass
    else:
        print "Invalid --allocator parameter: \"%s\"" % get_option('allocator')
        Exit(1)

    if has_option("heapcheck"):
        if not debugBuild:
            print( "--heapcheck needs --d or --dd" )
            Exit( 1 )

        if not conf.CheckCXXHeader( "google/heap-checker.h" ):
            print( "--heapcheck neads header 'google/heap-checker.h'" )
            Exit( 1 )

        conf.env.Append( CPPDEFINES=[ "HEAP_CHECKING" ] )
        conf.env.Append( CCFLAGS=["-fno-omit-frame-pointer"] )

    # ask each module to configure itself and the build environment.
    moduleconfig.configure_modules(mongo_modules, conf)

    return conf.Finish()

env = doConfigure( env )

env['PDB'] = '${TARGET.base}.pdb'

enforce_glibc = linux and releaseBuild and not has_option("no-glibc-check")

def checkErrorCodes():
    import buildscripts.errorcodes as x
    if x.checkErrorCodes() == False:
        print( "next id to use:" + str( x.getNextCode() ) )
        Exit(-1)

checkErrorCodes()

#  ---- Docs ----
def build_docs(env, target, source):
    from buildscripts import docs
    docs.main()

env.Alias("docs", [], [build_docs])
env.AlwaysBuild("docs")

#  ---- astyle ----

def doStyling( env , target , source ):

    res = utils.execsys( "astyle --version" )
    res = " ".join(res)
    if res.count( "2." ) == 0:
        print( "astyle 2.x needed, found:" + res )
        Exit(-1)

    files = utils.getAllSourceFiles() 
    files = filter( lambda x: not x.endswith( ".c" ) , files )

    cmd = "astyle --options=mongo_astyle " + " ".join( files )
    res = utils.execsys( cmd )
    print( res[0] )
    print( res[1] )


env.Alias( "style" , [] , [ doStyling ] )
env.AlwaysBuild( "style" )

# --- lint ----



def doLint( env , target , source ):
    import buildscripts.lint
    if not buildscripts.lint.run_lint( [ "src/mongo/" ] ):
        raise Exception( "lint errors" )

env.Alias( "lint" , [] , [ doLint ] )
env.AlwaysBuild( "lint" )


#  ----  INSTALL -------

def getSystemInstallName():
    dist_arch = GetOption("distarch")
    arch_name = processor if not dist_arch else dist_arch
    n = platform + "-" + arch_name
    if static:
        n += "-static"
    if has_option("nostrip"):
        n += "-debugsymbols"
    if nix and os.uname()[2].startswith("8."):
        n += "-tiger"

    if len(mongo_modules):
            n += "-" + "-".join(m.name for m in mongo_modules)

    try:
        findSettingsSetup()
        import settings
        if "distmod" in dir(settings):
            n = n + "-" + str(settings.distmod)
    except:
        pass

    dn = GetOption("distmod")
    if dn and len(dn) > 0:
        n = n + "-" + dn

    return n

def getCodeVersion():
    fullSource = open( "src/mongo/util/version.cpp" , "r" ).read()
    allMatches = re.findall( r"versionString.. = \"(.*?)\"" , fullSource );
    if len(allMatches) != 1:
        print( "can't find version # in code" )
        return None
    return allMatches[0]

mongoCodeVersion = getCodeVersion()
if mongoCodeVersion == None:
    Exit(-1)

if has_option('distname'):
    distName = GetOption( "distname" )
elif mongoCodeVersion[-1] not in ("+", "-"):
    dontReplacePackage = True
    distName = mongoCodeVersion
else:
    isBuildingLatest = True
    distName = utils.getGitBranchString("" , "-") + datetime.date.today().strftime("%Y-%m-%d")


env['SERVER_DIST_BASENAME'] = 'mongodb-%s-%s' % (getSystemInstallName(), distName)

distFile = "${SERVER_ARCHIVE}"

env['NIX_LIB_DIR'] = nixLibPrefix

#  ---- CONVENIENCE ----

def tabs( env, target, source ):
    from subprocess import Popen, PIPE
    from re import search, match
    diff = Popen( [ "git", "diff", "-U0", "origin", "master" ], stdout=PIPE ).communicate()[ 0 ]
    sourceFile = False
    for line in diff.split( "\n" ):
        if match( "diff --git", line ):
            sourceFile = not not search( "\.(h|hpp|c|cpp)\s*$", line )
        if sourceFile and match( "\+ *\t", line ):
            return True
    return False
env.Alias( "checkSource", [], [ tabs ] )
env.AlwaysBuild( "checkSource" )

def gitPush( env, target, source ):
    import subprocess
    return subprocess.call( [ "git", "push" ] )
env.Alias( "push", [ ".", "smoke", "checkSource" ], gitPush )
env.AlwaysBuild( "push" )


# ---- deploying ---

def s3push(localName, remoteName=None, platformDir=True):
    localName = str( localName )

    if isBuildingLatest:
        remotePrefix = utils.getGitBranchString("-") + "-latest"
    else:
        remotePrefix = "-" + distName

    findSettingsSetup()

    import simples3
    import settings

    s = simples3.S3Bucket( settings.bucket , settings.id , settings.key )

    if remoteName is None:
        remoteName = localName

    name = '%s-%s%s' % (remoteName , getSystemInstallName(), remotePrefix)
    lastDotIndex = localName.rfind('.')
    if lastDotIndex != -1:
        name += localName[lastDotIndex:]
    name = name.lower()

    if platformDir:
        name = platform + "/" + name

    print( "uploading " + localName + " to http://s3.amazonaws.com/" + s.name + "/" + name )
    if dontReplacePackage:
        for ( key , modify , etag , size ) in s.listdir( prefix=name ):
            print( "error: already a file with that name, not uploading" )
            Exit(2)
    s.put( name  , open( localName , "rb" ).read() , acl="public-read" );
    print( "  done uploading!" )

def s3shellpush( env , target , source ):
    s3push( "mongo" , "mongo-shell" )

env.Alias( "s3shell" , [ "mongo" ] , [ s3shellpush ] )
env.AlwaysBuild( "s3shell" )

def s3dist( env , target , source ):
    s3push( str(source[0]) , "mongodb" )

env.Alias( "dist" , '$SERVER_ARCHIVE' )
env.AlwaysBuild(env.Alias( "s3dist" , [ '$SERVER_ARCHIVE' ] , [ s3dist ] ))

# --- an uninstall target ---
if len(COMMAND_LINE_TARGETS) > 0 and 'uninstall' in COMMAND_LINE_TARGETS:
    SetOption("clean", 1)
    # By inspection, changing COMMAND_LINE_TARGETS here doesn't do
    # what we want, but changing BUILD_TARGETS does.
    BUILD_TARGETS.remove("uninstall")
    BUILD_TARGETS.append("install")

module_sconscripts = moduleconfig.get_module_sconscripts(mongo_modules)

# The following symbols are exported for use in subordinate SConscript files.
# Ideally, the SConscript files would be purely declarative.  They would only
# import build environment objects, and would contain few or no conditional
# statements or branches.
#
# Currently, however, the SConscript files do need some predicates for
# conditional decision making that hasn't been moved up to this SConstruct file,
# and they are exported here, as well.
Export("env")
Export("get_option")
Export("has_option use_system_version_of_library")
Export("mongoCodeVersion")
Export("usev8")
Export("v8version v8suffix")
Export("boostSuffix")
Export("darwin windows solaris linux freebsd nix openbsd")
Export('module_sconscripts')
Export("debugBuild optBuild")
Export("enforce_glibc")
Export("s3push")
Export("use_clang")
Export("wiredtiger")

def injectMongoIncludePaths(thisEnv):
    thisEnv.AppendUnique(CPPPATH=['$BUILD_DIR'])
env.AddMethod(injectMongoIncludePaths, 'InjectMongoIncludePaths')

env.SConscript('src/SConscript', variant_dir='$BUILD_DIR', duplicate=False)
env.SConscript(['SConscript.buildinfo', 'SConscript.smoke'])

def clean_old_dist_builds(env, target, source):
    prefix = "mongodb-%s-%s" % (platform, processor)
    filenames = sorted(os.listdir("."))
    filenames = [x for x in filenames if x.startswith(prefix)]
    to_keep = [x for x in filenames if x.endswith(".tgz") or x.endswith(".zip")][-2:]
    for filename in [x for x in filenames if x not in to_keep]:
        print "removing %s" % filename
        try:
            shutil.rmtree(filename)
        except:
            os.remove(filename)

env.Alias("dist_clean", [], [clean_old_dist_builds])
env.AlwaysBuild("dist_clean")

env.Alias('all', ['core', 'tools', 'dbtest', 'unittests', 'file_allocator_bench'])