fish-shell/configure.ac

#
# This file is the main build configuration file for fish. It is used
# to determine your systems capabilities, and tries to adapt fish to
# take maximum advantage of the services your system offers.
#
# Process this file using the 'autoconf' command to produce a working
# configure script, which should in turn be executed in order to
# configure the build process.
#

m4_syscmd([build_tools/git_version_gen.sh 2>/dev/null])

AC_PREREQ([2.60])
AC_INIT(fish,
        m4_esyscmd([cut -f 3 -d ' ' FISH-BUILD-VERSION-FILE | tr -d '\n']),
        fish-users@lists.sourceforge.net)

#
# List of output variables produced by this configure script
#

AC_SUBST(HAVE_GETTEXT)
AC_SUBST(HAVE_DOXYGEN)
AC_SUBST(LDFLAGS_FISH)
AC_SUBST(WCHAR_T_BITS)
AC_SUBST(EXTRA_PCRE2)


#
# If needed, run autoconf to regenerate the configure file
#
# This makes sure that after running autoconf once to create the first
# version of configure, we never again need to worry about manually
# running autoconf to handle an updates configure.ac.
#

AC_MSG_CHECKING([if autoconf needs to be run])
if test configure -ot configure.ac; then
  AC_MSG_RESULT([yes])
  if which autoconf >/dev/null; then
    # No need to provide any error messages if autoconf fails, the
    # shell and autconf should take care of that themselves
    AC_MSG_NOTICE([running autoconf])
    if autoconf; then
      ./configure "$@"
      exit
    fi
    exit 1
  else
    AC_MSG_ERROR(
      [cannot find the autoconf program in your path.
This program needs to be run whenever the configure.ac file is modified.
Please install it and try again.]
    )
  fi
else
  AC_MSG_RESULT([no])
fi


#
# If needed, run autoheader to regenerate config.h.in
#
# This makes sure we never ever have to run autoheader manually. It
# will be run whenever needed automatically.
#

AC_MSG_CHECKING([if autoheader needs to be run])
if test ! -f ./config.h.in -o config.h.in -ot configure.ac; then
  AC_MSG_RESULT([yes])
  if which autoheader >/dev/null; then
    AC_MSG_NOTICE([running autoheader])
    autoheader || exit 1
  else
    AC_MSG_ERROR(
      [cannot find the autoheader program in your path.
This program needs to be run whenever the configure.ac file is modified.
Please install it and try again.]
    )
  fi
else
  AC_MSG_RESULT([no])
fi

#
# Set up various programs needed for install
# Note AC_PROG_CXX sets CXXFLAGS if not set, which we want
# So ensure this happens before we modify CXXFLAGS below
#

AC_PROG_CXX([g++ c++])
AC_PROG_INSTALL
AC_PROG_SED
AC_LANG(C++)

echo "CXXFLAGS: $CXXFLAGS"

#
# Tell autoconf to create config.h header
#
AC_CONFIG_HEADERS(config.h)


#
# This adds markup to the code that results in a few extra compile
# time checks on recent GCC versions. It helps stop a few common bugs.
#

AH_BOTTOM([#if __GNUC__ >= 3
#ifndef __warn_unused
#define __warn_unused __attribute__ ((warn_unused_result))
#endif
#ifndef __sentinel
#define __sentinel __attribute__ ((sentinel))
#endif
#ifndef __packed
#define __packed __attribute__ ((packed))
#endif
#else
#define __warn_unused
#define __sentinel
#define __packed
#endif])


#
# Optionally drop gettext support
#

AC_ARG_WITH(
  gettext,
  AS_HELP_STRING(
    [--without-gettext],
    [do not translate messages, even if gettext is available]
  ),
  [local_gettext=$withval],
  [local_gettext=check]
)

AS_IF([test x$local_gettext != xno],
  [ AC_CHECK_PROGS( [found_msgfmt], [msgfmt], [no] )
    if test x$found_msgfmt != xno; then
      AC_DEFINE([USE_GETTEXT],[1],[Perform string translations with gettext])
    elif test "x$local_gettext" != "xcheck" ; then
      AC_MSG_FAILURE([--with-gettext was given, but the msgfmt program could not be found])
    else
      local_gettext=no
    fi
   ],
)

#
# Build/clean the documentation only if Doxygen is available
#

doxygen_minimum=1.8.7

AC_ARG_WITH(
  doxygen,
  AS_HELP_STRING(
    [--with-doxygen],
    [use Doxygen to regenerate documentation]
  ),
  [use_doxygen=$withval],
  [use_doxygen=auto]
)

AS_IF([test "$use_doxygen" != "no"],
  [
    AC_CHECK_PROGS([found_doxygen], [doxygen], [no])
    if test "$found_doxygen" != no; then
      # test version
      AC_MSG_CHECKING([the doxygen version])
      doxygen_version=`doxygen --version 2>/dev/null`
      AC_MSG_RESULT([$doxygen_version])
      dnl This requires autoconf 2.60 or newer
      AS_VERSION_COMPARE([$doxygen_version], [$doxygen_minimum],
        [ if test "$use_doxygen" = auto; then
            AC_MSG_WARN([doxygen version $doxygen_version found, but $doxygen_minimum required])
            HAVE_DOXYGEN=0
          else
            AC_MSG_FAILURE([doxygen version $doxygen_version found, but $doxygen_minimum required])
          fi
        ],
        [HAVE_DOXYGEN=1], [HAVE_DOXYGEN=1])
    elif test "$use_doxygen" != auto; then
      AC_MSG_FAILURE([--with-doxygen was given, but the doxygen program could not be found])
    else
      HAVE_DOXYGEN=0
    fi
  ],
)

#
# Try to enable large file support. This will make sure that on systems
# where off_t can be either 32 or 64 bit, the latter size is used. On
# other systems, this should do nothing. (Hopefully)
#

CXXFLAGS="$CXXFLAGS -D_LARGEFILE_SOURCE=1 -D_FILE_OFFSET_BITS=64"


# fish does not use exceptions
# Disabling exceptions saves about 20% (!) of the compiled code size
CXXFLAGS="$CXXFLAGS -fno-exceptions"


#
# -Wall is there to keep me on my toes
# But signed comparison warnings are way too aggressive
#

CXXFLAGS="$CXXFLAGS -Wall -Wno-sign-compare"

#
# This is needed in order to get the really cool backtraces on Linux
#

AC_MSG_CHECKING([for -rdynamic linker flag])
prev_LDFLAGS="$LDFLAGS"
LDFLAGS="$LDFLAGS -rdynamic"
AC_LINK_IFELSE([AC_LANG_PROGRAM([[]],[[]])],
               [
                AC_MSG_RESULT([yes])
                LDFLAGS_FISH="$LDFLAGS_FISH -rdynamic"
               ], [
                AC_MSG_RESULT([no])
                LDFLAGS_FISH="$LDFLAGS_FISH"
               ])
LDFLAGS="$prev_LDFLAGS"


#
# If we are compiling against glibc, set some flags to work around
# some rather stupid attempts to hide prototypes for *wprintf
# functions, as well as prototypes of various gnu extensions.
#

AC_MSG_CHECKING([if we are compiling against glibc])
AC_RUN_IFELSE(
  [
    AC_LANG_PROGRAM(
      [
        #include <stdlib.h>
        #ifdef __GLIBC__
        #define STATUS 0
        #else
        #define STATUS 1
        #endif
      ],
      [
        return STATUS;
      ]
    )
  ],
  [glibc=yes],
  [glibc=no]
)

if test "$glibc" = yes; then
  AC_MSG_RESULT(yes)

  #
  # This gives us access to prototypes for gnu extensions and C99
  # functions if we are compiling agains glibc. All GNU extensions
  # that are used must have a fallback implementation available in
  # fallback.h, in order to keep fish working on non-gnu platforms.
  #

  CXXFLAGS="$CXXFLAGS -D_GNU_SOURCE=1 -D_ISO99_SOURCE=1"
else
  AC_MSG_RESULT(no)
fi


#
# Test cpu for special handling of ppc
#
# This is used to skip use of tputs on ppc systems, since it seemed to
# be broken, at least on older debin-based systems. This is obviously
# not the right way to to detect whether this workaround should be
# used, since it catches far to many systems, but I do not have the
# hardware available to narrow this problem down, and in practice, it
# seems that tputs is never really needed.
#

AC_CANONICAL_TARGET

if test $target_cpu = powerpc; then
  AC_DEFINE([TPUTS_KLUDGE],[1],[Evil kludge to get Power based machines to work])
fi


#
# Solaris-specific flags go here
#

AC_MSG_CHECKING([if we are under Solaris])
case $target_os in
  solaris*)
    AC_DEFINE( __EXTENSIONS__, 1, [Macro to enable additional prototypes under Solaris])
    AC_MSG_RESULT(yes)
    ;;
  *)
    AC_MSG_RESULT(no)
    ;;
esac

#
# BSD-specific flags go here
#

AC_MSG_CHECKING([if we are under BSD])
case $target_os in
  *bsd*)
    AC_DEFINE( __BSD_VISIBLE, 1, [Macro to enable additional prototypes under BSD])
    AC_DEFINE( _NETBSD_SOURCE, 1, [Macro to enable additional prototypes under BSD])
    AC_MSG_RESULT(yes)
    ;;
  *)
    AC_MSG_RESULT(no)
    ;;
esac


#
# See if Linux procfs is present. This is used to get extra
# information about running processes.
#

AC_CHECK_FILES([/proc/self/stat])


#
# This is ued to tell the wgetopt library to translate strings. This
# way wgetopt can be dropped into any project without requiring i18n.
#

AC_DEFINE(
  [HAVE_TRANSLATE_H],
  [1],
  [Define to 1 if the wgettext function should be used for translating strings.]
)

# Disable curses macros that conflict with the STL
AC_DEFINE([NCURSES_NOMACROS], [1], [Define to 1 to disable ncurses macros that conflict with the STL])
AC_DEFINE([NOMACROS], [1], [Define to 1 to disable curses macros that conflict with the STL])

#
# Check presense of various libraries. This is done on a per-binary
# level, since including various extra libraries in all binaries only
# because thay are used by some of them can cause extra bloat and
# slower compiles when developing fish.
#

# Check for os dependant libraries for all binaries.
AC_SEARCH_LIBS( connect, socket, , [AC_MSG_ERROR([Cannot find the socket library, needed to build this package.] )] )
AC_SEARCH_LIBS( nanosleep, rt, , [AC_MSG_ERROR([Cannot find the rt library, needed to build this package.] )] )
AC_SEARCH_LIBS( shm_open, rt, , [AC_MSG_ERROR([Cannot find the rt library, needed to build this package.] )] )
AC_SEARCH_LIBS( pthread_create, pthread, , [AC_MSG_ERROR([Cannot find the pthread library, needed to build this package.] )] )
AC_SEARCH_LIBS( setupterm, [ncurses tinfo curses], , [AC_MSG_ERROR([Could not find a curses implementation, needed to build fish. If this is Linux, try running 'sudo apt-get install libncurses5-dev' or 'sudo yum install ncurses-devel'])] )
AC_SEARCH_LIBS( [nan], [m], [AC_DEFINE( [HAVE_NAN], [1], [Define to 1 if you have the nan function])] )
AC_SEARCH_LIBS( [backtrace_symbols_fd], [execinfo] )

if test x$local_gettext != xno; then
  AC_SEARCH_LIBS( gettext, intl,,)
fi

#
# Check presense of various header files
#

AC_CHECK_HEADERS([getopt.h termios.h sys/resource.h term.h ncurses/term.h ncurses.h ncurses/curses.h curses.h stropts.h siginfo.h sys/select.h sys/ioctl.h execinfo.h spawn.h sys/sysctl.h])

if test x$local_gettext != xno; then
  AC_CHECK_HEADERS([libintl.h])
fi


#
# Get the size in bits of wchar_t, needed for configuring the pcre2 build
# and for code that #includes pcre2.h
#

AC_CHECK_SIZEOF(wchar_t)
WCHAR_T_BITS=`expr 8 \* $ac_cv_sizeof_wchar_t`
AC_DEFINE_UNQUOTED([WCHAR_T_BITS], [$WCHAR_T_BITS], [The size of wchar_t in bits.])


#
# On some platforms (Solaris 10) adding -std=c99 in turn requires that
# _POSIX_C_SOURCE be defined to 200112L otherwise several
# POSIX-specific, non-ISO-C99 types/prototypes are made unavailable
# e.g. siginfo_t. Defining _XOPEN_SOURCE to 600 is compatible with
# the _POSIX_C_SOURCE value and provides a little assurance that
# extension functions' prototypes are available, e.g. killpg().
#
# Some other platforms (OS X), will remove types/prototypes/macros
# e.g. SIGWINCH if either _POSIX_C_SOURCE or _XOPEN_SOURCE is defined.
#
# This test adds these macros only if they enable a program that uses
# both Posix and non-standard features to compile, and that program
# does not compile without these macros.
#
# We try to make everyone happy.
#
# The ordering of the various autoconf tests is very critical as well:
#
# * This test needs to be run _after_ header detection tests, so that
# the proper headers are included.
#
# * This test needs to be run _before_ testing for the presense of any
# prototypes or other language functinality.
#
# * This test should be (but does not need to be) run after the
# conditional definition of __EXTENSIONS__, to avoid redundant tests.
#

XCXXFLAGS="$CXXFLAGS"

echo checking how to use -D_XOPEN_SOURCE=600 and -D_POSIX_C_SOURCE=200112L...
local_found_posix_switch=no

for i in "" "-D_POSIX_C_SOURCE=200112L" "-D_XOPEN_SOURCE=600 -D_POSIX_C_SOURCE=200112L"; do

  AC_MSG_CHECKING( if switches \"$i\" works)
  CXXFLAGS="$XCXXFLAGS $i"

  #
  # Try to run this program, which should test various extensions
  # and Posix functionality. If this program works, then everything
  # should work. Hopefully.
  #

  AC_TRY_LINK(
    [
      #include <stdlib.h>
      #include <stdio.h>
      #include <sys/types.h>

      /* POSIX, C89 and C99: POSIX extends this header.
       * For: kill(), killpg(), siginfo_t, sigset_t,
       * struct sigaction, sigemptyset(), sigaction(),
       * SIGIO and SIGWINCH.  */
      #include <signal.h>

      #ifdef HAVE_SIGINFO_H
      /* Neither POSIX, C89 nor C99: Solaris-specific (others?).
       * For: siginfo_t (also defined by signal.h when in
       * POSIX/extensions mode). */
      #include <siginfo.h>
      #endif

      #ifdef HAVE_SYS_IOCTL_H
      /* As above (under at least Linux and FreeBSD). */
      #include <sys/ioctl.h>
      #endif

      #ifdef HAVE_TERMIOS_H
      #include <termios.h>
      #endif
    ],
    [
      /* Avert high-level optimisation, by making the program's
       * return value depend on all tested identifiers. */
      long ret = 0;
      /* POSIX only: might be unhidden by _POSIX_C_SOURCE. */
      struct sigaction sa;
      sigset_t ss;
      siginfo_t info;
      ret += (long)(void *)&info + kill( 0, 0 ) +
        sigaction( 0, &sa, 0 ) + sigemptyset( &ss );
      /* Extended-POSIX: might be unhidden by _XOPEN_SOURCE. */
      ret += killpg( 0, 0 );
      /* Non-standard: might be hidden by the macros. */
      {
        struct winsize termsize;
        ret += (long)(void *)&termsize;
        ret += SIGWINCH + TIOCGWINSZ + SIGIO;
      }
      return ret;

    ],
    local_cv_use__posix_c_source=yes,
    local_cv_use__posix_c_source=no,
  )

  if test x$local_cv_use__posix_c_source = xyes; then
    AC_MSG_RESULT( yes )
    local_found_posix_switch=yes
    break;
  else
    AC_MSG_RESULT( no )
  fi

done

#
# We didn't find any combination of switches that worked - revert to
# no switches and hope that the fallbacks work.  A warning will be
# printed at the end of the configure script.
#

if test ! x$local_found_posix_switch = xyes; then
  CXXFLAGS="$XCXXFLAGS"
fi

#
# Detect nanoseconds fields in struct stat
#
AC_CHECK_MEMBERS([struct stat.st_mtimespec.tv_nsec])
AC_CHECK_MEMBERS([struct stat.st_mtim.tv_nsec])

#
# Check for D_TYPE in dirent, only on BSD and Linux
#
AC_STRUCT_DIRENT_D_TYPE

#
# Check for presense of various functions used by fish
#

AC_CHECK_FUNCS( wcsdup wcsndup wcslen wcscasecmp wcsncasecmp fwprintf )
AC_CHECK_FUNCS( futimes wcwidth wcswidth wcstok fputwc fgetwc )
AC_CHECK_FUNCS( wcstol wcslcat wcslcpy lrand48_r killpg mkostemp )
AC_CHECK_FUNCS( backtrace backtrace_symbols_fd sysconf getifaddrs )
AC_CHECK_FUNCS( futimens clock_gettime )

if test x$local_gettext != xno; then
  AC_CHECK_FUNCS( gettext dcgettext )

#
# The Makefile also needs to know if we have gettext, so it knows if
# the translations should be installed.
#
  AC_CHECK_FUNC( gettext, HAVE_GETTEXT=1, HAVE_GETTEXT=0 )
fi

#
# Here follows a list of small programs used to test for various
# features that Autoconf doesn't tell us about
#


#
# Check if realpath accepts null for its second argument
#

AC_MSG_CHECKING([if realpath accepts null for its second argument])
AC_RUN_IFELSE(
  [
    AC_LANG_PROGRAM(
      [
        #include <limits.h>
        #include <errno.h>
        #include <stdlib.h>
      ],
      [
        int status;
        char *res;
        res = realpath( "somefile", 0 );
        status = !(res != 0 || errno == ENOENT);
        exit( status );
      ]
    )
  ],
  [have_realpath_null=yes],
  [have_realpath_null=no]
)

if test "$have_realpath_null" = yes; then
  AC_MSG_RESULT(yes)
  AC_DEFINE(
    [HAVE_REALPATH_NULL],
    [1],
    [Define to 1 if realpath accepts null for its second argument.]
  )
else
  AC_MSG_RESULT(no)
fi


#
# Check if struct winsize and TIOCGWINSZ exist
#

AC_MSG_CHECKING([if struct winsize and TIOCGWINSZ exist])
AC_LINK_IFELSE(
  [
    AC_LANG_PROGRAM(
      [
        #ifdef HAVE_TERMIOS_H
        #include <termios.h>
        #endif

        #ifdef HAVE_SYS_IOCTL_H
        #include <sys/ioctl.h>
        #endif
      ],
      [
        struct winsize termsize = {0};
        TIOCGWINSZ;
      ]
    )
  ],
  [
    AC_MSG_RESULT(yes);
    AC_DEFINE([HAVE_WINSIZE], [1], [Define to 1 if the winsize struct and TIOCGWINSZ macro exist])
  ],
  [
    AC_MSG_RESULT(no)
  ]
)


#
# If we have a fwprintf in libc, test that it actually works. As of
# March 2006, it is broken under DragonFly BSD.
#

if test "$ac_cv_func_fwprintf" = yes; then

  AC_MSG_CHECKING([if fwprintf is broken])
  AC_RUN_IFELSE(
    [
      AC_LANG_PROGRAM(
        [
          #include <stdlib.h>
          #include <stdio.h>
          #include <locale.h>
          #include <wchar.h>
        ],
        [
          setlocale( LC_ALL, "" );
          fwprintf( stderr, L"%ls%ls", L"", L"fish:" );
        ]
      )
    ],
    [
      AC_MSG_RESULT(no)
    ],
    [
      AC_MSG_RESULT([yes])
      AC_DEFINE([HAVE_BROKEN_FWPRINTF], [1], [Define to 1 one if the implemented fwprintf is broken])
    ]
  )

fi


# Check for _nl_msg_cat_cntr symbol
AC_MSG_CHECKING([for _nl_msg_cat_cntr symbol])
AC_TRY_LINK(
  [
    #if HAVE_LIBINTL_H
    #include <libintl.h>
    #endif
  ],
  [
    extern int  _nl_msg_cat_cntr;
    int tmp = _nl_msg_cat_cntr;
    exit(tmp);
  ],
  have__nl_msg_cat_cntr=yes,
  have__nl_msg_cat_cntr=no
)
if test "$have__nl_msg_cat_cntr" = yes; then
  AC_MSG_RESULT(yes)
  AC_DEFINE(
    [HAVE__NL_MSG_CAT_CNTR],
    [1],
    [Define to 1 if the _nl_msg_cat_cntr symbol is exported.]
  )
else
  AC_MSG_RESULT(no)
fi

# Check for __environ symbol
AC_MSG_CHECKING([for __environ symbol])
AC_TRY_LINK(
  [
    #include <unistd.h>
  ],
  [
    extern char **__environ;
    char **tmp = __environ;
    exit(tmp!=0);
  ],
  have___environ=yes,
  have___environ=no
)
if test "$have___environ" = yes; then
  AC_MSG_RESULT(yes)
  AC_DEFINE(
    [HAVE___ENVIRON],
    [1],
    [Define to 1 if the __environ symbol is exported.]
  )
else
  AC_MSG_RESULT(no)
fi

# Check for sys_errlist
AC_MSG_CHECKING([for sys_errlist array])
AC_TRY_LINK(
  [
   #include <stdio.h>
  ],
  [
    const char *p;
    p = sys_errlist[sys_nerr];
  ],
  have_sys_errlist=yes,
  have_sys_errlist=no
)
if test "$have_sys_errlist" = yes; then
  AC_MSG_RESULT(yes)
  AC_DEFINE(
    [HAVE_SYS_ERRLIST],
    [1],
    [Define to 1 if the sys_errlist array is available.]
  )
else
  AC_MSG_RESULT(no)
fi

# Check for _sys_errs
AC_MSG_CHECKING([for _sys_errs array])
AC_TRY_LINK(
  [
   #include <string>
  ],
  [
    std::string p;
    extern const char _sys_errs[];
    extern const int _sys_index[];
    p = _sys_errs[_sys_index[0]];
  ],
  have__sys__errs=yes,
  have__sys__errs=no
)
if test "$have__sys__errs" = yes; then
  AC_MSG_RESULT(yes)
  AC_DEFINE(
    [HAVE__SYS__ERRS],
    [1],
    [Define to 1 if the _sys_errs array is available.]
  )
else
  AC_MSG_RESULT(no)
fi

# Check for Solaris curses tputs having fixed length parameter list.
AC_MSG_CHECKING([if we are using non varargs tparm.])
AC_COMPILE_IFELSE(
  [
    AC_LANG_PROGRAM(
      [
	#if HAVE_NCURSES_H
	#include <ncurses.h>
	#elif HAVE_NCURSES_CURSES_H
	#include <ncurses/curses.h>
	#else
	#include <curses.h>
	#endif

	#if HAVE_TERM_H
	#include <term.h>
	#elif HAVE_NCURSES_TERM_H
	#include <ncurses/term.h>
	#endif
      ],
      [
        tparm( "" );
      ]
    )
  ],
  [tparm_solaris_kludge=no],
  [tparm_solaris_kludge=yes]
)
if test "x$tparm_solaris_kludge" = "xyes"; then
  AC_MSG_RESULT(yes)
  AC_DEFINE(
    [TPARM_SOLARIS_KLUDGE],
    [1],
    [Define to 1 if tparm accepts a fixed amount of paramters.]
  )
else
  AC_MSG_RESULT(no)
fi

pcre2_min_version=10.21
EXTRA_PCRE2=
AC_ARG_WITH(
  included-pcre2,
  AS_HELP_STRING(
    [--without-included-pcre2],
    [build against the system PCRE2 library instead of the bundled version]
  ),
  [included_pcre2=$withval],
  [included_pcre2=auto]
)

if test "x$included_pcre2" != "xyes"; then

  # test for pcre2-config
  # can use either pcre2-config or pkgconfig here but only implement the former for now
  AC_CHECK_PROG(PCRE2_CONFIG, pcre2-config, pcre2-config)

  if test "x$PCRE2_CONFIG" != "x"; then
    dnl AC_MSG_CHECKING([for $WCHAR_T_BITS-bit PCRE2])
    XLIBS="$LIBS"
    LIBS="$LIBS "`$PCRE2_CONFIG --libs$WCHAR_T_BITS 2>/dev/null`
    XCXXFLAGS="$CXXFLAGS"
    CXXFLAGS="$CXXFLAGS"`$PCRE2_CONFIG --cflags`

    # cheat a bit here. the exact library is determined by $WCHAR_T_BITS,
    # and so AC_CHECK_LIB won't work (can't use a variable as library name)
    # AC_SEARCH_LIBS will use the existing $LIBS flags with no additional library first
    AC_SEARCH_LIBS([pcre2_compile_$WCHAR_T_BITS], [],
      [ # pcre2 lib found, check for minimum version
        pcre2_version=`$PCRE2_CONFIG --version`
        AS_VERSION_COMPARE([$pcre2_version], [$pcre2_min_version],
          [ # version < minimum
            AC_MSG_NOTICE([system PCRE2 library version $pcre2_version, need $pcre2_min_version or later])
            if test "x$included_pcre2" = "xno"; then
              # complain about pcre2 version
              AC_MSG_ERROR([system PCRE2 library is too old, but --without-included-pcre2 was given.])
            else
              # use the internal version; undo changes to LIBS/CXXFLAGS
              included_pcre2=yes
              LIBS="$XLIBS"
              CXXFLAGS="$XCXXFLAGS"
            fi
          ],
          [ # version == minimum
            working_pcre2=yes
          ],
          [ # version > minimum
            working_pcre2=yes
          ]
        )
      ],
      [ # fail case; undo the changes to LIBS/CXXFLAGS
       working_pcre2=no
       LIBS="$XLIBS"
       CXXFLAGS="$XCXXFLAGS"
      ]
    )
  fi

  if test "x$working_pcre2" = "xyes"; then
    AC_MSG_NOTICE([using system PCRE2 library])
  else
    # pcre2 size wrong or pcre2-config not found
    # is it OK to use the included version?
    if test "x$included_pcre2" = "xno"; then
      # complain
      AC_MSG_ERROR([cannot find system pcre2-config, but --without-included-pcre2 was given.
Make sure pcre2-config is installed and available in PATH.
You may need to install the PCRE2 development library for your system.])
    else
      # use the internal version
      included_pcre2=yes
    fi
  fi
fi

# Re-test as value may have changed.
if test "x$included_pcre2" = "xyes"; then
  # Build configure/Makefile for pcre2
  AC_MSG_NOTICE([using included PCRE2 library])
  # unfortunately these get added to the global configuration
  ac_configure_args="$ac_configure_args --disable-pcre2-8 --enable-pcre2-$WCHAR_T_BITS --disable-shared"
  AC_CONFIG_SUBDIRS([pcre2-10.21])

  PCRE2_CXXFLAGS='-I$(PCRE2_DIR)/src'
  PCRE2_LIBS='-L$(PCRE2_LIBDIR) -lpcre2-$(PCRE2_WIDTH)'

  # Make the binary depend on the PCRE2 libraries so they get built
  EXTRA_PCRE2='$(PCRE2_LIB)'
  CXXFLAGS="$CXXFLAGS $PCRE2_CXXFLAGS"
  LIBS="$LIBS $PCRE2_LIBS"
fi

# Allow configurable extra directories.
AC_SUBST(extra_completionsdir)
AC_ARG_WITH([extra-completionsdir],
            AS_HELP_STRING([--with-extra-completionsdir=DIR],
                           [path for extra completions]),
            [extra_completionsdir=$withval],
            [extra_completionsdir='${datadir}/fish/vendor_completions.d'])

AC_SUBST(extra_functionsdir)
AC_ARG_WITH([extra_functionsdir],
            AS_HELP_STRING([--with-extra-functionsdir=DIR],
                           [path for extra functions]),
            [extra_functionsdir=$withval],
            [extra_functionsdir='${datadir}/fish/vendor_functions.d'])

AC_SUBST(extra_confdir)
AC_ARG_WITH([extra-confdir],
            AS_HELP_STRING([--with-extra-confdir=DIR],
                           [path for extra conf]),
            [extra_confdir=$withval],
            [extra_confdir='${datadir}/fish/vendor_conf.d'])

# Tell the world what we know.
AC_CONFIG_FILES([Makefile])
AC_OUTPUT

if test ! x$local_found_posix_switch = xyes; then
  echo "Can't find a combination of switches to enable common extensions like detecting window size."
  echo "Some fish features may be disabled."
fi

echo "fish is now configured."
echo "Use 'make' and 'make install' to build and install fish."