configure.ac - third_party/swift-corelibs-libdispatch - Git at Google

 #
 # When this file changes, rerun autogen.sh.
 #

 AC_PREREQ(2.69)
 AC_INIT([libdispatch], [1.3], [https://bugs.swift.org], [libdispatch], [https://github.com/apple/swift-corelibs-libdispatch])
 AC_REVISION([$$])
 AC_CONFIG_AUX_DIR(config)
 AC_CONFIG_HEADER([config/config_ac.h])
 AC_CONFIG_MACRO_DIR([m4])
 ac_clean_files=a.out.dSYM
 AM_MAINTAINER_MODE

 AC_CANONICAL_BUILD
 AC_CANONICAL_HOST
 AC_CANONICAL_TARGET

 #
 # Command line argument to specify build variant (default to release).
 # Impacts default value of CFLAGS et al. so must come before AC_PROG_CC
 #
 AC_ARG_WITH([build-variant],
   [AS_HELP_STRING([--with-build-variant=release|debug|releaseassert|releasedebuginfo], [Specify build variant [default=release]])],
   [dispatch_build_variant=${withval}],
   [dispatch_build_variant=release]
 )
 AS_CASE([$dispatch_build_variant],
   [debug], [
     default_compiler_flags="-g -O0"
     dispatch_enable_asserts=true
     dispatch_enable_optimization=false
   ],
   [release], [
     default_compiler_flags="-O2"
     dispatch_enable_asserts=false
     dispatch_enable_optimization=true
   ],
   [releaseassert], [
     default_compiler_flags="-O2"
     dispatch_enable_asserts=true
     dispatch_enable_optimization=true
   ],
   [releasedebuginfo], [
     default_compiler_flags="-g -O2"
     dispatch_enable_asserts=false
     dispatch_enable_optimization=true
   ],
   [AC_MSG_ERROR("invalid build-variant $dispatch_build_variant")]
 )
 AM_CONDITIONAL(DISPATCH_ENABLE_ASSERTS, $dispatch_enable_asserts)
 AM_CONDITIONAL(DISPATCH_ENABLE_OPTIMIZATION, $dispatch_enable_optimization)

 : ${CFLAGS=$default_compiler_flags}
 : ${CXXFLAGS=$default_compiler_flags}
 : ${OBJCFLAGS=$default_compiler_flags}
 : ${OBJCXXFLAGS=$default_compiler_flags}

 AC_PROG_CC([clang gcc cc])
 AC_PROG_CXX([clang++ g++ c++])
 AC_PROG_OBJC([clang gcc cc])
 AC_PROG_OBJCXX([clang++ g++ c++])

 #
 # Android cross-compilation support
 #
 AC_ARG_WITH([android-ndk],
   [AS_HELP_STRING([--with-android-ndk],
     [Android NDK location])], [
   android_ndk=${withval}
 ])
 AC_ARG_WITH([android-ndk-gcc-version],
   [AS_HELP_STRING([--with-android-ndk-gcc-version],
     [Android NDK GCC version [defaults=4.9]])],
   [android_ndk_gcc_version=${withval}], [android_ndk_gcc_version=4.9])
 AC_ARG_WITH([android-api-level],
   [AS_HELP_STRING([--with-android-api-level],
     [Android API level to link with])], [
   android_api_level=${withval}
 ])
 AC_ARG_ENABLE([android],
   [AS_HELP_STRING([--enable-android],
     [Compile for Android])], [
   android=true

   # Override values until there's real support for multiple Android platforms
   host=armv7-none-linux-androideabi
   host_alias=arm-linux-androideabi
   host_cpu=armv7
   host_os=linux-androideabi
   host_vendor=unknown
   arch=arm

   sysroot=${android_ndk}/platforms/android-${android_api_level}/arch-${arch}
   toolchain=${android_ndk}/toolchains/${host_alias}-${android_ndk_gcc_version}/prebuilt/linux-${build_cpu}

   CFLAGS="$CFLAGS -target ${host_alias} --sysroot=${sysroot} -B${toolchain}/${host_alias}/bin"
   CXXFLAGS="$CXXFLAGS -target ${host_alias} --sysroot=${sysroot} -B${toolchain}/${host_alias}/bin"
   SWIFTC_FLAGS="-target ${host} -sdk ${sysroot} -L${toolchain}/lib/gcc/${host_alias}/${android_ndk_gcc_version}.x"
   LIBS="$LIBS -L${toolchain}/lib/gcc/${host_alias}/${android_ndk_gcc_version}.x"
   LDFLAGS="$LDFLAGS -Wc,'-target','${host_alias}','-B${toolchain}/${host_alias}/bin'"

   # FIXME: empty CFLAGS and CXXFLAGS are assumed for this to work.
   # FIXME: there should be a more elegant way to do this
   ac_configure_args=`echo $ac_configure_args | sed -e "s/ 'CFLAGS='//" -e "s/ 'CXXFLAGS='//"`
   # CFLAGS, CXXFLAGS and LIBS needs to be passed to libkqueue and libpwq
   ac_configure_args="$ac_configure_args --enable-bionic-libc 'CFLAGS=$CFLAGS' 'CXXFLAGS=$CXXFLAGS' 'LIBS=$LIBS'"
 ], [android=false])
 AM_CONDITIONAL(ANDROID, $android)

 #
 # On Mac OS X, some required header files come from other source packages;
 # allow specifying where those are.
 #
 AC_ARG_WITH([apple-libpthread-source],
   [AS_HELP_STRING([--with-apple-libpthread-source],
     [Specify path to Apple libpthread source])], [
   apple_libpthread_source_path=${withval}
   CPPFLAGS="$CPPFLAGS -isystem $apple_libpthread_source_path"
 ])

 AC_ARG_WITH([apple-libplatform-source],
   [AS_HELP_STRING([--with-apple-libplatform-source],
     [Specify path to Apple libplatform source])], [
   apple_libplatform_source_include_path=${withval}/include
   CPPFLAGS="$CPPFLAGS -isystem $apple_libplatform_source_include_path"
 ])

 AC_ARG_WITH([apple-xnu-source],
   [AS_HELP_STRING([--with-apple-xnu-source],
     [Specify path to Apple XNU source])], [
   apple_xnu_source_libsyscall_path=${withval}/libsyscall
   apple_xnu_source_libproc_path=${withval}/libsyscall/wrappers/libproc
   apple_xnu_source_libkern_path=${withval}/libkern
   apple_xnu_source_bsd_path=${withval}/bsd
   apple_xnu_source_osfmk_path=${withval}/osfmk
   CPPFLAGS="$CPPFLAGS -idirafter $apple_xnu_source_libkern_path -isystem $apple_xnu_source_bsd_path -isystem $apple_xnu_source_libsyscall_path -isystem $apple_xnu_source_libproc_path "
 ])

 AC_CACHE_CHECK([for System.framework/PrivateHeaders], dispatch_cv_system_privateheaders,
   [AS_IF([test -d /System/Library/Frameworks/System.framework/PrivateHeaders],
     [dispatch_cv_system_privateheaders=yes], [dispatch_cv_system_privateheaders=no])]
 )
 AS_IF([test "x$dispatch_cv_system_privateheaders" != "xno"],
   [CPPFLAGS="$CPPFLAGS -isystem /System/Library/Frameworks/System.framework/PrivateHeaders"]
 )

 #
 # On Mac OS X, libdispatch_init is automatically invoked during libSystem
 # process initialization.  On other systems, it is tagged as a library
 # constructor to be run by automatically by the runtime linker.
 #
 AC_ARG_ENABLE([libdispatch-init-constructor],
   [AS_HELP_STRING([--disable-libdispatch-init-constructor],
     [Disable libdispatch_init as a constructor])],,
   [AS_IF([test -f /usr/lib/system/libdispatch.dylib],
     [enable_libdispatch_init_constructor=no])]
 )
 AS_IF([test "x$enable_libdispatch_init_constructor" != "xno"],
   [AC_DEFINE(USE_LIBDISPATCH_INIT_CONSTRUCTOR, 1,
     [Define to tag libdispatch_init as a constructor])]
 )

 #
 # On Mac OS X libdispatch can use the non-portable direct pthread TSD functions
 #
 AC_ARG_ENABLE([apple-tsd-optimizations],
   [AS_HELP_STRING([--enable-apple-tsd-optimizations],
     [Use non-portable pthread TSD optimizations for Mac OS X.])]
 )
 AS_IF([test "x$enable_apple_tsd_optimizations" = "xyes"],
   [AC_DEFINE(USE_APPLE_TSD_OPTIMIZATIONS, 1,
     [Define to use non-portable pthread TSD optimizations for Mac OS X)])]
 )

 #
 # Enable building Swift overlay support into libdispatch
 #
 AC_ARG_WITH([swift-toolchain],
   [AS_HELP_STRING([--with-swift-toolchain], [Specify path to Swift toolchain])],
   [swift_toolchain_path=${withval}
    AC_DEFINE(HAVE_SWIFT, 1, [Define if building for Swift])
    SWIFTC="$swift_toolchain_path/bin/swiftc"
    case $target_os in
       *android*)
 	    os_string="android"
 	    ;;
       linux*)
 	    os_string="linux"
 	    case $target_cpu in
 		    armv7l*)
 			target_cpu="armv7"
 			;;
 		    armv6l*)
 			target_cpu="armv6"
 			;;
 			*)
             esac
 	    ;;
 	  *)
         os_string=$target_os
 		;;
 	esac
    SWIFT_LIBDIR="$swift_toolchain_path/lib/swift/$os_string/$target_cpu"
    have_swift=true],
   [have_swift=false]
 )
 AM_CONDITIONAL(HAVE_SWIFT, $have_swift)
 AC_SUBST([SWIFTC])
 AC_SUBST([SWIFTC_FLAGS])
 AC_SUBST([SWIFT_LIBDIR])
 AC_SUBST([OS_STRING], ["$os_string"])

 #
 # Enable use of gold linker when building the Swift overlay
 # to avoid a symbol relocation issue.
 # Ultimately the request to use gold should be passed in as an arg
 #
 AC_CHECK_PROG(use_gold_linker, ld.gold, true, false)
 AM_CONDITIONAL(USE_GOLD_LINKER, $use_gold_linker)

 #
 # Enable an extended test suite that includes
 # tests that are too unreliable to be enabled by
 # default in the Swift CI environment, but are still
 # useful for libdispatch developers to be able to run.
 #
 AC_ARG_ENABLE([extended-test-suite],
   [AS_HELP_STRING([--enable-extended-test-suite],
     [Include additional test cases that may fail intermittently])]
 )
 AM_CONDITIONAL(EXTENDED_TEST_SUITE, test "x$enable_extended_test_suite" = "xyes")

 #
 # Enable __thread based TSD on platforms where it is efficient
 # Allow override based on command line argument to configure
 #
 AC_ARG_ENABLE([thread-local-storage],
   [AS_HELP_STRING([--enable-thread-local-storage],
     [Enable usage of thread local storage via __thread])],,
   [case $target_os in
       linux*)
         enable_thread_local_storage=yes
 	    ;;
       *)
         enable_thread_local_storage=no
    esac]
 )
 AS_IF([test "x$enable_thread_local_storage" = "xyes"],
   [AC_DEFINE(DISPATCH_USE_THREAD_LOCAL_STORAGE, 1,
     [Enable usage of thread local storage via __thread])]
 )

 AC_USE_SYSTEM_EXTENSIONS
 AM_INIT_AUTOMAKE([foreign no-dependencies subdir-objects])
 LT_INIT([disable-static])

 AC_PROG_INSTALL
 AC_PATH_PROGS(MIG, mig)
 AC_PATH_PROG(DTRACE, dtrace)
 AS_IF([test "x$DTRACE" != "x"], [use_dtrace=true],[
   use_dtrace=false
   CPPFLAGS="$CPPFLAGS -DDISPATCH_USE_DTRACE=0"
 ])
 AM_CONDITIONAL(USE_DTRACE, $use_dtrace)
 AC_PATH_PROG(LEAKS, leaks)
 AS_IF([test "x$LEAKS" != "x"],
   [AC_DEFINE(HAVE_LEAKS, 1, [Define if Apple leaks program is present])
    have_leaks=true],
   [have_leaks=false]
 )
 AM_CONDITIONAL(HAVE_LEAKS, $have_leaks)

 DISPATCH_C_ATOMIC_BUILTINS

 case $dispatch_cv_atomic in
   yes) ;;
   -march*) MARCH_FLAGS="$dispatch_cv_atomic"
          AC_SUBST([MARCH_FLAGS]) ;;
   *) AC_MSG_ERROR([No gcc builtin atomic operations available]) ;;
 esac

 #
 # Find libraries we will need
 #
 AC_SEARCH_LIBS(clock_gettime, rt)
 AC_SEARCH_LIBS(pthread_create, pthread)

 AC_CHECK_FUNCS([strlcpy getprogname], [],
   [PKG_CHECK_MODULES(BSD_OVERLAY, libbsd-overlay,[
     AC_DEFINE(HAVE_STRLCPY, 1, [])
     AC_DEFINE(HAVE_GETPROGNAME, 1, [])
   ])], [#include <string.h>]
 )

 #
 # Checks for header files.
 #
 AC_HEADER_STDC
 AC_CHECK_HEADERS([TargetConditionals.h pthread_np.h malloc/malloc.h libkern/OSCrossEndian.h libkern/OSAtomic.h sys/guarded.h fcntl.h])

 # hack for pthread/private headers
 AS_IF([test -n "$apple_libpthread_source_path" -a -n "$apple_xnu_source_osfmk_path"], [
   saveCPPFLAGS="$CPPFLAGS"
   CPPFLAGS="$CPPFLAGS -I."
   ln -fsh "$apple_libpthread_source_path"/private/tsd_private.h pthread_machdep.h
   ln -fsh "$apple_libpthread_source_path"/private pthread
   ln -fsh "$apple_xnu_source_osfmk_path" System
   mkdir -p mach && ln -fsh "$apple_xnu_source_osfmk_path"/mach/coalition.h mach
 ])
 AC_CHECK_HEADERS([pthread_machdep.h pthread/qos.h])

 # pthread_workqueues.
 # We can either use libdispatch's internal_workqueue or pthread_workqueue.
 # If not specifically configured, default to internal_workqueues on
 # Linux and pthread_workqueue on all other platforms.
 # On any platform, if pthread_workqueue is not available, fall back
 # to using internal_workqueue.
 AC_ARG_ENABLE([internal-libpwq],
   [AS_HELP_STRING([--enable-internal-libpwq],
     [Use libdispatch's own implementation of pthread workqueues.])],,
   [case $target_os in
       linux*)
         enable_internal_libpwq=yes
 	    ;;
       *)
         enable_internal_libpwq=no
    esac]
 )
 AS_IF([test "x$enable_internal_libpwq" = "xyes"],
   [AC_DEFINE(DISPATCH_USE_INTERNAL_WORKQUEUE, 1, [Use libdispatch's own implementation of pthread workqueues])
    have_pthread_workqueues=false,
    dispatch_use_internal_workqueue=true],
   [AC_CHECK_HEADERS([pthread/workqueue_private.h pthread_workqueue.h],
      [AC_DEFINE(HAVE_PTHREAD_WORKQUEUES, 1, [Define if pthread work queues are present])
       have_pthread_workqueues=true,
 	  dispatch_use_internal_workqueue=false],
      [have_pthread_workqueues=false,
 	  dispatch_use_internal_workqueue=true]
   )]
 )
 AM_CONDITIONAL(DISPATCH_USE_INTERNAL_WORKQUEUE, $dispatch_use_internal_workqueue)
 AM_CONDITIONAL(HAVE_PTHREAD_WORKQUEUES, $have_pthread_workqueues)

 AC_CHECK_HEADERS([libproc_internal.h], [], [], [#include <mach/mach.h>])
 AC_CHECK_FUNCS([pthread_workqueue_setdispatch_np _pthread_workqueue_init])
 AS_IF([test -n "$apple_libpthread_source_path" -a -n "$apple_xnu_source_osfmk_path"], [
   rm -f pthread_machdep.h pthread System mach/coalition.h
   CPPFLAGS="$saveCPPFLAGS"
   AC_CONFIG_COMMANDS([src/pthread_machdep.h],
     [ln -fsh "$apple_libpthread_source_path"/private/tsd_private.h src/pthread_machdep.h],
     [apple_libpthread_source_path="$apple_libpthread_source_path"])
   AC_CONFIG_COMMANDS([src/pthread],
     [ln -fsh "$apple_libpthread_source_path"/private src/pthread],
     [apple_libpthread_source_path="$apple_libpthread_source_path"])
   AC_CONFIG_COMMANDS([src/System],
     [ln -fsh "$apple_xnu_source_osfmk_path" src/System],
     [apple_xnu_source_osfmk_path="$apple_xnu_source_osfmk_path"])
   AC_CONFIG_COMMANDS([src/mach/coalition.h],
     [ln -fsh "$apple_xnu_source_osfmk_path"/mach/coalition.h src/mach],
     [apple_xnu_source_osfmk_path="$apple_xnu_source_osfmk_path"])
 ])
 # hack for xnu/bsd/sys/event.h EVFILT_SOCK declaration
 AS_IF([test -n "$apple_xnu_source_bsd_path"], [
   CPPFLAGS="$CPPFLAGS -DPRIVATE=1"
 ])

 #
 # Check for CoreFoundation, Foundation and objc
 #
 AC_CHECK_HEADER([CoreFoundation/CoreFoundation.h],
   [have_corefoundation=true], [have_corefoundation=false]
 )
 AM_CONDITIONAL(HAVE_COREFOUNDATION, $have_corefoundation)

 AC_LANG_PUSH([Objective C])
 AC_CHECK_HEADER([Foundation/Foundation.h],
   [have_foundation=true], [have_foundation=false]
 )
 AM_CONDITIONAL(HAVE_FOUNDATION, $have_foundation)
 AC_CHECK_HEADER([objc/NSObject.h], [
   AC_DEFINE(HAVE_OBJC, 1, [Define if you have the Objective-C runtime])
   have_objc=true], [have_objc=false]
 )
 AM_CONDITIONAL(USE_OBJC, $have_objc)
 AC_LANG_POP([Objective C])

 #
 # We use the availability of mach.h to decide whether to compile in all sorts
 # of Machisms, including using Mach ports as event sources, etc.
 #
 AC_CHECK_HEADER([mach/mach.h], [
   AC_DEFINE(HAVE_MACH, 1, [Define if mach is present])
   AC_DEFINE(__DARWIN_NON_CANCELABLE, 1, [Define if using Darwin $NOCANCEL])
   have_mach=true], [have_mach=false]
 )
 AM_CONDITIONAL(USE_MIG, $have_mach)
 AC_CHECK_FUNCS([mach_port_construct])

 #
 # Find functions and declarations we care about.
 #
 AC_CHECK_DECLS([CLOCK_UPTIME, CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_UPTIME_FAST, CLOCK_MONOTONIC_COARSE], [], [],
   [[#include <time.h>]])
 AC_CHECK_DECLS([NOTE_NONE, NOTE_REAP, NOTE_REVOKE, NOTE_SIGNAL, NOTE_LOWAT], [], [],
   [[#include <sys/event.h>]])
 AC_CHECK_DECLS([FD_COPY], [], [], [[#include <sys/select.h>]])
 AC_CHECK_DECLS([SIGEMT], [], [], [[#include <signal.h>]])
 AC_CHECK_DECLS([VQ_UPDATE, VQ_VERYLOWDISK, VQ_QUOTA, VQ_NEARLOWDISK, VQ_DESIRED_DISK], [], [], [[#include <sys/mount.h>]])
 AC_CHECK_DECLS([program_invocation_short_name], [], [], [[#include <errno.h>]])
 AC_CHECK_FUNCS([pthread_key_init_np pthread_main_np mach_absolute_time mach_approximate_time malloc_create_zone sysconf])

 AC_CHECK_DECLS([POSIX_SPAWN_START_SUSPENDED],
   [have_posix_spawn_start_suspended=true], [have_posix_spawn_start_suspended=false],
   [[#include <sys/spawn.h>]]
 )
 AM_CONDITIONAL(HAVE_POSIX_SPAWN_START_SUSPENDED, $have_posix_spawn_start_suspended)

 AC_CHECK_FUNC([sem_init],
   [have_sem_init=true], [have_sem_init=false]
 )

 AC_CHECK_HEADER([linux/futex.h], [
   AC_DEFINE(HAVE_FUTEX, 1, [Define if linux/futex.h is present])
   have_futex=true], [have_futex=false]
 )

 #
 # We support both Mach semaphores and POSIX semaphores; if the former are
 # available, prefer them.
 #
 AC_MSG_CHECKING([what semaphore type to use]);
 AS_IF([test "x$have_mach" = "xtrue"],
   [AC_DEFINE(USE_MACH_SEM, 1, [Define to use Mach semaphores])
     AC_MSG_RESULT([Mach semaphores])],
   [test "x$have_sem_init" = "xtrue"],
   [AC_DEFINE(USE_POSIX_SEM, 1, [Define to use POSIX semaphores])
     AC_MSG_RESULT([POSIX semaphores])],
   [AC_MSG_ERROR([no supported semaphore type])]
 )

 AC_CHECK_HEADERS([sys/cdefs.h], [], [],
   [#ifdef HAVE_SYS_CDEFS_H
    #include <sys/cdefs.h>
    #endif])

 DISPATCH_C_BLOCKS

 AC_CACHE_CHECK([for -fvisibility=hidden], [dispatch_cv_cc_visibility_hidden], [
   saveCFLAGS="$CFLAGS"
   CFLAGS="$CFLAGS -fvisibility=hidden"
   AC_LINK_IFELSE([AC_LANG_PROGRAM([
     extern __attribute__ ((visibility ("default"))) int foo; int foo;], [foo = 0;])],
     [dispatch_cv_cc_visibility_hidden="yes"], [dispatch_cv_cc_visibility_hidden="no"])
   CFLAGS="$saveCFLAGS"
 ])
 AS_IF([test "x$dispatch_cv_cc_visibility_hidden" != "xno"], [
     VISIBILITY_FLAGS="-fvisibility=hidden"
 ])
 AC_SUBST([VISIBILITY_FLAGS])

 AC_CACHE_CHECK([for -momit-leaf-frame-pointer], [dispatch_cv_cc_omit_leaf_fp], [
   saveCFLAGS="$CFLAGS"
   CFLAGS="$CFLAGS -momit-leaf-frame-pointer"
   AC_LINK_IFELSE([AC_LANG_PROGRAM([
     extern int foo(void); int foo(void) {return 1;}], [foo();])],
     [dispatch_cv_cc_omit_leaf_fp="yes"], [dispatch_cv_cc_omit_leaf_fp="no"])
   CFLAGS="$saveCFLAGS"
 ])
 AS_IF([test "x$dispatch_cv_cc_omit_leaf_fp" != "xno"], [
   OMIT_LEAF_FP_FLAGS="-momit-leaf-frame-pointer"
 ])
 AC_SUBST([OMIT_LEAF_FP_FLAGS])

 AS_IF([test "x$have_mach" = "xtrue"], [
   AC_CACHE_CHECK([for darwin linker], [dispatch_cv_ld_darwin], [
     saveLDFLAGS="$LDFLAGS"
     LDFLAGS="$LDFLAGS -dynamiclib -compatibility_version 1.2.3 -current_version 4.5.6 -dead_strip"
     AC_LINK_IFELSE([AC_LANG_PROGRAM([
       extern int foo; int foo;], [foo = 0;])],
       [dispatch_cv_ld_darwin="yes"], [dispatch_cv_ld_darwin="no"])
     LDFLAGS="$saveLDFLAGS"
   ])
 ])
 AM_CONDITIONAL(HAVE_DARWIN_LD, [test "x$dispatch_cv_ld_darwin" == "xyes"])

 #
 # symlink platform-specific module.modulemap files
 #
 AS_CASE([$target_os],
   [darwin*], [ dispatch_module_map_os=darwin ],
   [ dispatch_module_map_os=generic ]
 )
 AC_CONFIG_COMMANDS([modulemaps], [
       ln -fs $dispatch_module_map_os/module.modulemap $ac_top_srcdir/dispatch/module.modulemap
       ln -fs $dispatch_module_map_os/module.modulemap $ac_top_srcdir/private/module.modulemap
   ],
   [dispatch_module_map_os="$dispatch_module_map_os"]
 )

 #
 # Temporary: some versions of clang do not mark __builtin_trap() as
 # __attribute__((__noreturn__)).  Detect and add if required.
 #
 AC_COMPILE_IFELSE(
   [AC_LANG_PROGRAM([void __attribute__((__noreturn__)) temp(void) { __builtin_trap(); }], [])],
   [AC_DEFINE(HAVE_NORETURN_BUILTIN_TRAP, 1, [Define if __builtin_trap marked noreturn])]
 )

 #
 # Add option to avoid building tests
 #
 AC_ARG_ENABLE([build-tests],
   [AS_HELP_STRING([--disable-build-tests], [Disable tests compilation])])
 AM_CONDITIONAL(BUILD_TESTS, [test "x$enable_build_tests" != "xno"])

 #
 # Generate Makefiles.
 #
 AC_CONFIG_FILES([Makefile dispatch/Makefile man/Makefile os/Makefile private/Makefile src/Makefile tests/Makefile])

 #
 # Generate testsuite links
 #
 AC_CONFIG_LINKS([tests/dispatch:$ac_top_srcdir/private tests/leaks-wrapper:tests/leaks-wrapper.sh])

 AC_OUTPUT
	#
	# When this file changes, rerun autogen.sh.
	#

	AC_PREREQ(2.69)
	AC_INIT([libdispatch], [1.3], [https://bugs.swift.org], [libdispatch], [https://github.com/apple/swift-corelibs-libdispatch])
	AC_REVISION([$$])
	AC_CONFIG_AUX_DIR(config)
	AC_CONFIG_HEADER([config/config_ac.h])
	AC_CONFIG_MACRO_DIR([m4])
	ac_clean_files=a.out.dSYM
	AM_MAINTAINER_MODE

	AC_CANONICAL_BUILD
	AC_CANONICAL_HOST
	AC_CANONICAL_TARGET

	#
	# Command line argument to specify build variant (default to release).
	# Impacts default value of CFLAGS et al. so must come before AC_PROG_CC
	#
	AC_ARG_WITH([build-variant],
	[AS_HELP_STRING([--with-build-variant=release\|debug\|releaseassert\|releasedebuginfo], [Specify build variant [default=release]])],
	[dispatch_build_variant=${withval}],
	[dispatch_build_variant=release]
	)
	AS_CASE([$dispatch_build_variant],
	[debug], [
	default_compiler_flags="-g -O0"
	dispatch_enable_asserts=true
	dispatch_enable_optimization=false
	],
	[release], [
	default_compiler_flags="-O2"
	dispatch_enable_asserts=false
	dispatch_enable_optimization=true
	],
	[releaseassert], [
	default_compiler_flags="-O2"
	dispatch_enable_asserts=true
	dispatch_enable_optimization=true
	],
	[releasedebuginfo], [
	default_compiler_flags="-g -O2"
	dispatch_enable_asserts=false
	dispatch_enable_optimization=true
	],
	[AC_MSG_ERROR("invalid build-variant $dispatch_build_variant")]
	)
	AM_CONDITIONAL(DISPATCH_ENABLE_ASSERTS, $dispatch_enable_asserts)
	AM_CONDITIONAL(DISPATCH_ENABLE_OPTIMIZATION, $dispatch_enable_optimization)

	: ${CFLAGS=$default_compiler_flags}
	: ${CXXFLAGS=$default_compiler_flags}
	: ${OBJCFLAGS=$default_compiler_flags}
	: ${OBJCXXFLAGS=$default_compiler_flags}

	AC_PROG_CC([clang gcc cc])
	AC_PROG_CXX([clang++ g++ c++])
	AC_PROG_OBJC([clang gcc cc])
	AC_PROG_OBJCXX([clang++ g++ c++])

	#
	# Android cross-compilation support
	#
	AC_ARG_WITH([android-ndk],
	[AS_HELP_STRING([--with-android-ndk],
	[Android NDK location])], [
	android_ndk=${withval}
	])
	AC_ARG_WITH([android-ndk-gcc-version],
	[AS_HELP_STRING([--with-android-ndk-gcc-version],
	[Android NDK GCC version [defaults=4.9]])],
	[android_ndk_gcc_version=${withval}], [android_ndk_gcc_version=4.9])
	AC_ARG_WITH([android-api-level],
	[AS_HELP_STRING([--with-android-api-level],
	[Android API level to link with])], [
	android_api_level=${withval}
	])
	AC_ARG_ENABLE([android],
	[AS_HELP_STRING([--enable-android],
	[Compile for Android])], [
	android=true

	# Override values until there's real support for multiple Android platforms
	host=armv7-none-linux-androideabi
	host_alias=arm-linux-androideabi
	host_cpu=armv7
	host_os=linux-androideabi
	host_vendor=unknown
	arch=arm

	sysroot=${android_ndk}/platforms/android-${android_api_level}/arch-${arch}
	toolchain=${android_ndk}/toolchains/${host_alias}-${android_ndk_gcc_version}/prebuilt/linux-${build_cpu}

	CFLAGS="$CFLAGS -target ${host_alias} --sysroot=${sysroot} -B${toolchain}/${host_alias}/bin"
	CXXFLAGS="$CXXFLAGS -target ${host_alias} --sysroot=${sysroot} -B${toolchain}/${host_alias}/bin"
	SWIFTC_FLAGS="-target ${host} -sdk ${sysroot} -L${toolchain}/lib/gcc/${host_alias}/${android_ndk_gcc_version}.x"
	LIBS="$LIBS -L${toolchain}/lib/gcc/${host_alias}/${android_ndk_gcc_version}.x"
	LDFLAGS="$LDFLAGS -Wc,'-target','${host_alias}','-B${toolchain}/${host_alias}/bin'"

	# FIXME: empty CFLAGS and CXXFLAGS are assumed for this to work.
	# FIXME: there should be a more elegant way to do this
	ac_configure_args=`echo $ac_configure_args \| sed -e "s/ 'CFLAGS='//" -e "s/ 'CXXFLAGS='//"`
	# CFLAGS, CXXFLAGS and LIBS needs to be passed to libkqueue and libpwq
	ac_configure_args="$ac_configure_args --enable-bionic-libc 'CFLAGS=$CFLAGS' 'CXXFLAGS=$CXXFLAGS' 'LIBS=$LIBS'"
	], [android=false])
	AM_CONDITIONAL(ANDROID, $android)

	#
	# On Mac OS X, some required header files come from other source packages;
	# allow specifying where those are.
	#
	AC_ARG_WITH([apple-libpthread-source],
	[AS_HELP_STRING([--with-apple-libpthread-source],
	[Specify path to Apple libpthread source])], [
	apple_libpthread_source_path=${withval}
	CPPFLAGS="$CPPFLAGS -isystem $apple_libpthread_source_path"
	])

	AC_ARG_WITH([apple-libplatform-source],
	[AS_HELP_STRING([--with-apple-libplatform-source],
	[Specify path to Apple libplatform source])], [
	apple_libplatform_source_include_path=${withval}/include
	CPPFLAGS="$CPPFLAGS -isystem $apple_libplatform_source_include_path"
	])

	AC_ARG_WITH([apple-xnu-source],
	[AS_HELP_STRING([--with-apple-xnu-source],
	[Specify path to Apple XNU source])], [
	apple_xnu_source_libsyscall_path=${withval}/libsyscall
	apple_xnu_source_libproc_path=${withval}/libsyscall/wrappers/libproc
	apple_xnu_source_libkern_path=${withval}/libkern
	apple_xnu_source_bsd_path=${withval}/bsd
	apple_xnu_source_osfmk_path=${withval}/osfmk
	CPPFLAGS="$CPPFLAGS -idirafter $apple_xnu_source_libkern_path -isystem $apple_xnu_source_bsd_path -isystem $apple_xnu_source_libsyscall_path -isystem $apple_xnu_source_libproc_path "
	])

	AC_CACHE_CHECK([for System.framework/PrivateHeaders], dispatch_cv_system_privateheaders,
	[AS_IF([test -d /System/Library/Frameworks/System.framework/PrivateHeaders],
	[dispatch_cv_system_privateheaders=yes], [dispatch_cv_system_privateheaders=no])]
	)
	AS_IF([test "x$dispatch_cv_system_privateheaders" != "xno"],
	[CPPFLAGS="$CPPFLAGS -isystem /System/Library/Frameworks/System.framework/PrivateHeaders"]
	)

	#
	# On Mac OS X, libdispatch_init is automatically invoked during libSystem
	# process initialization. On other systems, it is tagged as a library
	# constructor to be run by automatically by the runtime linker.
	#
	AC_ARG_ENABLE([libdispatch-init-constructor],
	[AS_HELP_STRING([--disable-libdispatch-init-constructor],
	[Disable libdispatch_init as a constructor])],,
	[AS_IF([test -f /usr/lib/system/libdispatch.dylib],
	[enable_libdispatch_init_constructor=no])]
	)
	AS_IF([test "x$enable_libdispatch_init_constructor" != "xno"],
	[AC_DEFINE(USE_LIBDISPATCH_INIT_CONSTRUCTOR, 1,
	[Define to tag libdispatch_init as a constructor])]
	)

	#
	# On Mac OS X libdispatch can use the non-portable direct pthread TSD functions
	#
	AC_ARG_ENABLE([apple-tsd-optimizations],
	[AS_HELP_STRING([--enable-apple-tsd-optimizations],
	[Use non-portable pthread TSD optimizations for Mac OS X.])]
	)
	AS_IF([test "x$enable_apple_tsd_optimizations" = "xyes"],
	[AC_DEFINE(USE_APPLE_TSD_OPTIMIZATIONS, 1,
	[Define to use non-portable pthread TSD optimizations for Mac OS X)])]
	)

	#
	# Enable building Swift overlay support into libdispatch
	#
	AC_ARG_WITH([swift-toolchain],
	[AS_HELP_STRING([--with-swift-toolchain], [Specify path to Swift toolchain])],
	[swift_toolchain_path=${withval}
	AC_DEFINE(HAVE_SWIFT, 1, [Define if building for Swift])
	SWIFTC="$swift_toolchain_path/bin/swiftc"
	case $target_os in
	android)
	os_string="android"
	;;
	linux*)
	os_string="linux"
	case $target_cpu in
	armv7l*)
	target_cpu="armv7"
	;;
	armv6l*)
	target_cpu="armv6"
	;;
	*)
	esac
	;;
	*)
	os_string=$target_os
	;;
	esac
	SWIFT_LIBDIR="$swift_toolchain_path/lib/swift/$os_string/$target_cpu"
	have_swift=true],
	[have_swift=false]
	)
	AM_CONDITIONAL(HAVE_SWIFT, $have_swift)
	AC_SUBST([SWIFTC])
	AC_SUBST([SWIFTC_FLAGS])
	AC_SUBST([SWIFT_LIBDIR])
	AC_SUBST([OS_STRING], ["$os_string"])

	#
	# Enable use of gold linker when building the Swift overlay
	# to avoid a symbol relocation issue.
	# Ultimately the request to use gold should be passed in as an arg
	#
	AC_CHECK_PROG(use_gold_linker, ld.gold, true, false)
	AM_CONDITIONAL(USE_GOLD_LINKER, $use_gold_linker)

	#
	# Enable an extended test suite that includes
	# tests that are too unreliable to be enabled by
	# default in the Swift CI environment, but are still
	# useful for libdispatch developers to be able to run.
	#
	AC_ARG_ENABLE([extended-test-suite],
	[AS_HELP_STRING([--enable-extended-test-suite],
	[Include additional test cases that may fail intermittently])]
	)
	AM_CONDITIONAL(EXTENDED_TEST_SUITE, test "x$enable_extended_test_suite" = "xyes")

	#
	# Enable __thread based TSD on platforms where it is efficient
	# Allow override based on command line argument to configure
	#
	AC_ARG_ENABLE([thread-local-storage],
	[AS_HELP_STRING([--enable-thread-local-storage],
	[Enable usage of thread local storage via __thread])],,
	[case $target_os in
	linux*)
	enable_thread_local_storage=yes
	;;
	*)
	enable_thread_local_storage=no
	esac]
	)
	AS_IF([test "x$enable_thread_local_storage" = "xyes"],
	[AC_DEFINE(DISPATCH_USE_THREAD_LOCAL_STORAGE, 1,
	[Enable usage of thread local storage via __thread])]
	)

	AC_USE_SYSTEM_EXTENSIONS
	AM_INIT_AUTOMAKE([foreign no-dependencies subdir-objects])
	LT_INIT([disable-static])

	AC_PROG_INSTALL
	AC_PATH_PROGS(MIG, mig)
	AC_PATH_PROG(DTRACE, dtrace)
	AS_IF([test "x$DTRACE" != "x"], [use_dtrace=true],[
	use_dtrace=false
	CPPFLAGS="$CPPFLAGS -DDISPATCH_USE_DTRACE=0"
	])
	AM_CONDITIONAL(USE_DTRACE, $use_dtrace)
	AC_PATH_PROG(LEAKS, leaks)
	AS_IF([test "x$LEAKS" != "x"],
	[AC_DEFINE(HAVE_LEAKS, 1, [Define if Apple leaks program is present])
	have_leaks=true],
	[have_leaks=false]
	)
	AM_CONDITIONAL(HAVE_LEAKS, $have_leaks)

	DISPATCH_C_ATOMIC_BUILTINS

	case $dispatch_cv_atomic in
	yes) ;;
	-march*) MARCH_FLAGS="$dispatch_cv_atomic"
	AC_SUBST([MARCH_FLAGS]) ;;
	*) AC_MSG_ERROR([No gcc builtin atomic operations available]) ;;
	esac

	#
	# Find libraries we will need
	#
	AC_SEARCH_LIBS(clock_gettime, rt)
	AC_SEARCH_LIBS(pthread_create, pthread)

	AC_CHECK_FUNCS([strlcpy getprogname], [],
	[PKG_CHECK_MODULES(BSD_OVERLAY, libbsd-overlay,[
	AC_DEFINE(HAVE_STRLCPY, 1, [])
	AC_DEFINE(HAVE_GETPROGNAME, 1, [])
	])], [#include <string.h>]
	)

	#
	# Checks for header files.
	#
	AC_HEADER_STDC
	AC_CHECK_HEADERS([TargetConditionals.h pthread_np.h malloc/malloc.h libkern/OSCrossEndian.h libkern/OSAtomic.h sys/guarded.h fcntl.h])

	# hack for pthread/private headers
	AS_IF([test -n "$apple_libpthread_source_path" -a -n "$apple_xnu_source_osfmk_path"], [
	saveCPPFLAGS="$CPPFLAGS"
	CPPFLAGS="$CPPFLAGS -I."
	ln -fsh "$apple_libpthread_source_path"/private/tsd_private.h pthread_machdep.h
	ln -fsh "$apple_libpthread_source_path"/private pthread
	ln -fsh "$apple_xnu_source_osfmk_path" System
	mkdir -p mach && ln -fsh "$apple_xnu_source_osfmk_path"/mach/coalition.h mach
	])
	AC_CHECK_HEADERS([pthread_machdep.h pthread/qos.h])

	# pthread_workqueues.
	# We can either use libdispatch's internal_workqueue or pthread_workqueue.
	# If not specifically configured, default to internal_workqueues on
	# Linux and pthread_workqueue on all other platforms.
	# On any platform, if pthread_workqueue is not available, fall back
	# to using internal_workqueue.
	AC_ARG_ENABLE([internal-libpwq],
	[AS_HELP_STRING([--enable-internal-libpwq],
	[Use libdispatch's own implementation of pthread workqueues.])],,
	[case $target_os in
	linux*)
	enable_internal_libpwq=yes
	;;
	*)
	enable_internal_libpwq=no
	esac]
	)
	AS_IF([test "x$enable_internal_libpwq" = "xyes"],
	[AC_DEFINE(DISPATCH_USE_INTERNAL_WORKQUEUE, 1, [Use libdispatch's own implementation of pthread workqueues])
	have_pthread_workqueues=false,
	dispatch_use_internal_workqueue=true],
	[AC_CHECK_HEADERS([pthread/workqueue_private.h pthread_workqueue.h],
	[AC_DEFINE(HAVE_PTHREAD_WORKQUEUES, 1, [Define if pthread work queues are present])
	have_pthread_workqueues=true,
	dispatch_use_internal_workqueue=false],
	[have_pthread_workqueues=false,
	dispatch_use_internal_workqueue=true]
	)]
	)
	AM_CONDITIONAL(DISPATCH_USE_INTERNAL_WORKQUEUE, $dispatch_use_internal_workqueue)
	AM_CONDITIONAL(HAVE_PTHREAD_WORKQUEUES, $have_pthread_workqueues)

	AC_CHECK_HEADERS([libproc_internal.h], [], [], [#include <mach/mach.h>])
	AC_CHECK_FUNCS([pthread_workqueue_setdispatch_np _pthread_workqueue_init])
	AS_IF([test -n "$apple_libpthread_source_path" -a -n "$apple_xnu_source_osfmk_path"], [
	rm -f pthread_machdep.h pthread System mach/coalition.h
	CPPFLAGS="$saveCPPFLAGS"
	AC_CONFIG_COMMANDS([src/pthread_machdep.h],
	[ln -fsh "$apple_libpthread_source_path"/private/tsd_private.h src/pthread_machdep.h],
	[apple_libpthread_source_path="$apple_libpthread_source_path"])
	AC_CONFIG_COMMANDS([src/pthread],
	[ln -fsh "$apple_libpthread_source_path"/private src/pthread],
	[apple_libpthread_source_path="$apple_libpthread_source_path"])
	AC_CONFIG_COMMANDS([src/System],
	[ln -fsh "$apple_xnu_source_osfmk_path" src/System],
	[apple_xnu_source_osfmk_path="$apple_xnu_source_osfmk_path"])
	AC_CONFIG_COMMANDS([src/mach/coalition.h],
	[ln -fsh "$apple_xnu_source_osfmk_path"/mach/coalition.h src/mach],
	[apple_xnu_source_osfmk_path="$apple_xnu_source_osfmk_path"])
	])
	# hack for xnu/bsd/sys/event.h EVFILT_SOCK declaration
	AS_IF([test -n "$apple_xnu_source_bsd_path"], [
	CPPFLAGS="$CPPFLAGS -DPRIVATE=1"
	])

	#
	# Check for CoreFoundation, Foundation and objc
	#
	AC_CHECK_HEADER([CoreFoundation/CoreFoundation.h],
	[have_corefoundation=true], [have_corefoundation=false]
	)
	AM_CONDITIONAL(HAVE_COREFOUNDATION, $have_corefoundation)

	AC_LANG_PUSH([Objective C])
	AC_CHECK_HEADER([Foundation/Foundation.h],
	[have_foundation=true], [have_foundation=false]
	)
	AM_CONDITIONAL(HAVE_FOUNDATION, $have_foundation)
	AC_CHECK_HEADER([objc/NSObject.h], [
	AC_DEFINE(HAVE_OBJC, 1, [Define if you have the Objective-C runtime])
	have_objc=true], [have_objc=false]
	)
	AM_CONDITIONAL(USE_OBJC, $have_objc)
	AC_LANG_POP([Objective C])

	#
	# We use the availability of mach.h to decide whether to compile in all sorts
	# of Machisms, including using Mach ports as event sources, etc.
	#
	AC_CHECK_HEADER([mach/mach.h], [
	AC_DEFINE(HAVE_MACH, 1, [Define if mach is present])
	AC_DEFINE(__DARWIN_NON_CANCELABLE, 1, [Define if using Darwin $NOCANCEL])
	have_mach=true], [have_mach=false]
	)
	AM_CONDITIONAL(USE_MIG, $have_mach)
	AC_CHECK_FUNCS([mach_port_construct])

	#
	# Find functions and declarations we care about.
	#
	AC_CHECK_DECLS([CLOCK_UPTIME, CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_UPTIME_FAST, CLOCK_MONOTONIC_COARSE], [], [],
	[[#include <time.h>]])
	AC_CHECK_DECLS([NOTE_NONE, NOTE_REAP, NOTE_REVOKE, NOTE_SIGNAL, NOTE_LOWAT], [], [],
	[[#include <sys/event.h>]])
	AC_CHECK_DECLS([FD_COPY], [], [], [[#include <sys/select.h>]])
	AC_CHECK_DECLS([SIGEMT], [], [], [[#include <signal.h>]])
	AC_CHECK_DECLS([VQ_UPDATE, VQ_VERYLOWDISK, VQ_QUOTA, VQ_NEARLOWDISK, VQ_DESIRED_DISK], [], [], [[#include <sys/mount.h>]])
	AC_CHECK_DECLS([program_invocation_short_name], [], [], [[#include <errno.h>]])
	AC_CHECK_FUNCS([pthread_key_init_np pthread_main_np mach_absolute_time mach_approximate_time malloc_create_zone sysconf])

	AC_CHECK_DECLS([POSIX_SPAWN_START_SUSPENDED],
	[have_posix_spawn_start_suspended=true], [have_posix_spawn_start_suspended=false],
	[[#include <sys/spawn.h>]]
	)
	AM_CONDITIONAL(HAVE_POSIX_SPAWN_START_SUSPENDED, $have_posix_spawn_start_suspended)

	AC_CHECK_FUNC([sem_init],
	[have_sem_init=true], [have_sem_init=false]
	)

	AC_CHECK_HEADER([linux/futex.h], [
	AC_DEFINE(HAVE_FUTEX, 1, [Define if linux/futex.h is present])
	have_futex=true], [have_futex=false]
	)

	#
	# We support both Mach semaphores and POSIX semaphores; if the former are
	# available, prefer them.
	#
	AC_MSG_CHECKING([what semaphore type to use]);
	AS_IF([test "x$have_mach" = "xtrue"],
	[AC_DEFINE(USE_MACH_SEM, 1, [Define to use Mach semaphores])
	AC_MSG_RESULT([Mach semaphores])],
	[test "x$have_sem_init" = "xtrue"],
	[AC_DEFINE(USE_POSIX_SEM, 1, [Define to use POSIX semaphores])
	AC_MSG_RESULT([POSIX semaphores])],
	[AC_MSG_ERROR([no supported semaphore type])]
	)

	AC_CHECK_HEADERS([sys/cdefs.h], [], [],
	[#ifdef HAVE_SYS_CDEFS_H
	#include <sys/cdefs.h>
	#endif])

	DISPATCH_C_BLOCKS

	AC_CACHE_CHECK([for -fvisibility=hidden], [dispatch_cv_cc_visibility_hidden], [
	saveCFLAGS="$CFLAGS"
	CFLAGS="$CFLAGS -fvisibility=hidden"
	AC_LINK_IFELSE([AC_LANG_PROGRAM([
	extern __attribute__ ((visibility ("default"))) int foo; int foo;], [foo = 0;])],
	[dispatch_cv_cc_visibility_hidden="yes"], [dispatch_cv_cc_visibility_hidden="no"])
	CFLAGS="$saveCFLAGS"
	])
	AS_IF([test "x$dispatch_cv_cc_visibility_hidden" != "xno"], [
	VISIBILITY_FLAGS="-fvisibility=hidden"
	])
	AC_SUBST([VISIBILITY_FLAGS])

	AC_CACHE_CHECK([for -momit-leaf-frame-pointer], [dispatch_cv_cc_omit_leaf_fp], [
	saveCFLAGS="$CFLAGS"
	CFLAGS="$CFLAGS -momit-leaf-frame-pointer"
	AC_LINK_IFELSE([AC_LANG_PROGRAM([
	extern int foo(void); int foo(void) {return 1;}], [foo();])],
	[dispatch_cv_cc_omit_leaf_fp="yes"], [dispatch_cv_cc_omit_leaf_fp="no"])
	CFLAGS="$saveCFLAGS"
	])
	AS_IF([test "x$dispatch_cv_cc_omit_leaf_fp" != "xno"], [
	OMIT_LEAF_FP_FLAGS="-momit-leaf-frame-pointer"
	])
	AC_SUBST([OMIT_LEAF_FP_FLAGS])

	AS_IF([test "x$have_mach" = "xtrue"], [
	AC_CACHE_CHECK([for darwin linker], [dispatch_cv_ld_darwin], [
	saveLDFLAGS="$LDFLAGS"
	LDFLAGS="$LDFLAGS -dynamiclib -compatibility_version 1.2.3 -current_version 4.5.6 -dead_strip"
	AC_LINK_IFELSE([AC_LANG_PROGRAM([
	extern int foo; int foo;], [foo = 0;])],
	[dispatch_cv_ld_darwin="yes"], [dispatch_cv_ld_darwin="no"])
	LDFLAGS="$saveLDFLAGS"
	])
	])
	AM_CONDITIONAL(HAVE_DARWIN_LD, [test "x$dispatch_cv_ld_darwin" == "xyes"])

	#
	# symlink platform-specific module.modulemap files
	#
	AS_CASE([$target_os],
	[darwin*], [ dispatch_module_map_os=darwin ],
	[ dispatch_module_map_os=generic ]
	)
	AC_CONFIG_COMMANDS([modulemaps], [
	ln -fs $dispatch_module_map_os/module.modulemap $ac_top_srcdir/dispatch/module.modulemap
	ln -fs $dispatch_module_map_os/module.modulemap $ac_top_srcdir/private/module.modulemap
	],
	[dispatch_module_map_os="$dispatch_module_map_os"]
	)

	#
	# Temporary: some versions of clang do not mark __builtin_trap() as
	# __attribute__((__noreturn__)). Detect and add if required.
	#
	AC_COMPILE_IFELSE(
	[AC_LANG_PROGRAM([void __attribute__((__noreturn__)) temp(void) { __builtin_trap(); }], [])],
	[AC_DEFINE(HAVE_NORETURN_BUILTIN_TRAP, 1, [Define if __builtin_trap marked noreturn])]
	)

	#
	# Add option to avoid building tests
	#
	AC_ARG_ENABLE([build-tests],
	[AS_HELP_STRING([--disable-build-tests], [Disable tests compilation])])
	AM_CONDITIONAL(BUILD_TESTS, [test "x$enable_build_tests" != "xno"])

	#
	# Generate Makefiles.
	#
	AC_CONFIG_FILES([Makefile dispatch/Makefile man/Makefile os/Makefile private/Makefile src/Makefile tests/Makefile])

	#
	# Generate testsuite links
	#
	AC_CONFIG_LINKS([tests/dispatch:$ac_top_srcdir/private tests/leaks-wrapper:tests/leaks-wrapper.sh])

	AC_OUTPUT