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autoconf是一个产生可以自动配置源代码包

* Major changes in Autoconf 2.60

  Released 2006-06-23, by Ralf Wildenhues.

** Autoconf no longer depends on whether m4wrap is FIFO (as Posix requires)
  or LIFO (as in GNU M4 1.4.x).  GNU M4 2.0 is expected to conform to Posix
  here, so m4wrap/m4_wrap users should no longer depend on LIFO behavior.

** Provide a way to turn off warnings about the changed directory variables.

* Major changes in Autoconf 2.59d

  Released 2006-06-05, by Ralf Wildenhues.

** GNU make now recommended for VPATH builds
  INSTALL now suggests VPATH builds (e.g., "sh ../srcdir/configure")
  only if you use GNU make.  In practice, other 'make' implementations
  have too many subtle incompatibilities in their support for VPATH.
  Many packages (including Autoconf itself) are portable to other
  'make' implementations, but some packages are not, and recommending
  GNU make keeps the installation instructions simpler.

** Even more safety checks for the new Directory variables:
  Warn about suspicious `${datarootdir}' found in config files output.

** AC_TRY_COMMAND, AC_TRY_EVAL, ac_config_guess, ac_config_sub, ac_configure
  These never-documented macros and variables have been marked with
  comments saying that they may be removed in a future release,
  because their use can lead to unintended code being executed.
  If you need functionality that only these macros or variables
  currently supply, please write [e-mail].

** AC_SUBST, AC_DEFINE
  Literal arguments to these are passed to m4_pattern_allow now.

** AC_PROG_CC_STDC
  Passing 'ac_cv_prog_cc_stdc=no' to 'configure' now sets ac_cv_prog_cc_c99
  and ac_cv_prog_cc_c89 to 'no' as well, for backward compatibility with
  obsolete K&R tests in the Automake test suite.

** AC_PROG_CXX_C_O
  New macro.

** AC_PROG_MKDIR_P
  New macro.

** AS_MKDIR_P
  Now more robust with special characters in file names, or when
  multiple processes create the same directory at the same time.

** Obsolescent macros
  The documentation now says that the following macros are obsolescent:
  they test for problems that are so old that they are no longer of
  practical importance on current systems.

    AC_C_BACKSLASH_A       AC_FUNC_MEMCMP            AC_HEADER_DIRENT
    AC_C_CONST             AC_FUNC_SELECT_ARGTYPES   AC_HEADER_STAT
    AC_C_PROTOTYPES        AC_FUNC_SETPGRP           AC_HEADER_STDC
    AC_C_STRINGIZE         AC_FUNC_SETVBUF_REVERSED  AC_HEADER_SYS_WAIT
    AC_C_VOLATILE          AC_FUNC_STAT              AC_HEADER_TIME
    AC_FUNC_CLOSEDIR_VOID  AC_FUNC_STRFTIME          AC_ISC_POSIX
    AC_FUNC_GETPGRP        AC_FUNC_UTIME_NULL        AC_PROG_GCC_TRADITIONAL
    AC_FUNC_LSTAT          AC_FUNC_VPRINTF           AC_STRUCT_TM

  New programs need not use these macros.  We have no current plans to
  remove them.

** autoreconf
  For compatibility with future Libtool 2.0, autoreconf will invoke
  libtoolize with the option `--ltdl' now, if LT_CONFIG_LTDL_DIR is
  used.

* Major changes in Autoconf 2.59c

  Released 2006-04-12, by Ralf Wildenhues.

** The configure command now redirects standard input from /dev/null,
  to help avoid problems with subsidiary commands that might mistakenly
  read standard input.  AS_ORIGINAL_STDIN_FD points to the original
  standard input before this redirection, if you really want configure to
  read from standard input.

** Directory variables adjusted to recent changes in the GNU Coding Standards.
  The following directory variables are new:

    datarootdir   read-only architecture-independent data root [PREFIX/share]
    localedir     locale-specific message catalogs [DATAROOTDIR/locale]
    docdir        documentation root [DATAROOTDIR/doc/PACKAGE]
    htmldir       html documentation [DOCDIR]
    dvidir        dvi documentation [DOCDIR]
    pdfdir        pdf documentation [DOCDIR]
    psdir         ps documentation [DOCDIR]

  The following variables have new default values:

    datadir       read-only architecture-independent data [DATAROOTDIR]
    infodir       info documentation [DATAROOTDIR/info]
    mandir        man documentation [DATAROOTDIR/man]

  This means that if you use any of `@datadir@', `@infodir@', or
  `@mandir@' in a file, you will have to ensure `${datarootdir}' is
  defined in this file.  As a temporary measure, if any of those are
  found but no mention of `datarootdir', the substitutions will be
  replaced with values that do not contain `${datarootdir}', and a
  warning will be issued.

** @top_builddir@ is now a dir name: it is always nonempty and doesn't have
  a trailing slash.  Similar change will be made to ac_top_builddir in a
  future release; the old style value, which matches (../)*, is (and will
  continue to be) available as ac_top_build_prefix.

** AC_C_TYPEOF
  New macro to check for support of 'typeof' syntax a la GNU C.

** AC_CHECK_DECLS_ONCE, AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS_ONCE
  New "once-only" variants of commonly-used macros, to make 'configure'
  smaller and faster in common cases.

** AC_FUNC_STRTOLD
  New macro to check for strtold with C99 semantics.

** AC_HEADER_ASSERT
  New macro that lets builder disable assertions at 'configure'-time.

** AC_PATH_X
  Now checks for X11/Xlib.h and XrmInitialize (X proper) rather than
  X11/Intrinsic.h and XtMalloc (Xt).

** AC_PRESERVE_HELP_ORDER
  New macro that causes `configure' to display help strings for AC_ARG_ENABLE
  and AC_ARG_WITH arguments in one region, in the order defined.  The default
  behavior is to group options of each classes separately.

** AC_PROG_CC, AC_PROG_CXX
  No longer automatically arrange to declare the 'exit' function of C,
  when a C++ compiler is used.  Standard Autoconf macros no longer use
  'exit', so this is no longer an issue for them.  If you use C++, and
  want to call 'exit', you'll have to arrange for its declaration
  yourself.  But we now suggest you return from 'main' instead.

** AC_PROG_CC_C89, AC_PROG_CC_C99
  New macros for ISO C99 support.  AC_PROG_CC_C89 and AC_PROG_CC_C99
  check for ANSI C89 and ISO C99 support respectively.

** AC_PROG_CC_STDC
  Has been unobsoleted, and will check if the compiler supports ISO
  C99, falling back to ANSI C89 if not.  ac_cv_prog_cc_stdc is
  retained for backwards compatibility, assuming the value of
  ac_cv_prog_cc_c99 or ac_cv_prog_cc_c89 (whichever is valid, in
  that order).

** AC_STRUCT_DIRENT_D_INO, AC_STRUCT_DIRENT_D_TYPE
  New macros for checking commonly-used members of struct dirent.

** AC_SUBST
  The substituted value can now contain newlines.

** AC_SUBST_FILE
  The substitution now occurs only when @variable@ is on a line by itself,
  optionally surrounded by spaces and tabs.  The whole line is replaced.

** AC_TYPE_LONG_DOUBLE, AC_TYPE_LONG_DOUBLE_WIDER
  New macros to check for long double, and whether it is wider than double.
  The old macro AC_C_TYPE_LONG_DOUBLE has been marked as obsolete;
  applications should switch to the new macro.

** AC_TYPE_INT8_T, AC_TYPE_INT16_T, AC_TYPE_INT32_T, AC_TYPE_INT64_T,
   AC_TYPE_INTMAX_T, AC_TYPE_INTPTR_T, AC_TYPE_LONG_LONG_INT, AC_TYPE_SSIZE_T,
   AC_TYPE_UINT8_T, AC_TYPE_UINT16_T, AC_TYPE_UINT32_T, AC_TYPE_UINT64_T,
   AC_TYPE_UINTMAX_T, AC_TYPE_UINTPTR_T, AC_TYPE_UNSIGNED_LONG_LONG_INT
  New macros to check for C99 and POSIX types.

** AC_USE_SYSTEM_EXTENSIONS
  New macro to enable extensions to Posix.

** AH_HEADER
  New macro which is defined to the name of the first declared config header
  or undefined if no config headers have been declared yet.

** AS_HELP_STRING
  The macro correctly handles quadrigraphs now.

** AS_BOURNE_COMPATIBLE, AS_SHELL_SANITIZE, AS_CASE
  These macros are new or published now.

** AT_COPYRIGHT
  New macro for copyright notices in testsuite files.

** ALLOCA, LIBOBJS, LTLIBOBJS
  Object names added to these variables are now prefixed with `${LIBOBJDIR}',
  as in `${LIBOBJDIR}alloca.o'.  LIBOBJDIR is meant to be defined from
  `Makefile.in' in case the object files lie in a different directory.
  The LIBOBJDIR feature is experimental.

** autoreconf
  Supports --no-recursive now.

** New macros to support Erlang/OTP.
  New macros for configuring paths to Erlang tools and libraries:
  AC_ERLANG_PATH_ERLC, AC_ERLANG_NEED_ERLC, AC_ERLANG_PATH_ERL,
  AC_ERLANG_NEED_ERL, AC_ERLANG_CHECK_LIB, AC_ERLANG_SUBST_ROOT_DIR,
  AC_ERLANG_SUBST_LIB_DIR.

  New macros for configuring installation of Erlang libraries:
  AC_ERLANG_SUBST_INSTALL_LIB_DIR, AC_ERLANG_SUBST_INSTALL_LIB_SUBDIR.

** The manual now mentions Gnulib more prominently.

** New macros to support Objective C.
  AC_PROG_OBJC, AC_PROG_OBJCPP.

* Major changes in Autoconf 2.59b

  Released 2004-08-20, by Paul Eggert.

** AC_CHECK_ALIGNOF
  New macro that computes the default alignment of a type.

** AC_CHECK_TOOL, AC_PATH_TOOL, AC_CHECK_TOOLS
  When cross-compiling, these macros will give a warning if the tool
  is not prefixed.  In the future, unprefixed cross tools will not
  be detected; please consult the info documentation for information
  about the reason of this change.

** AC_CHECK_TARGET_TOOL, AC_PATH_TARGET_TOOL, AC_CHECK_TARGET_TOOLS
  New macros that detect programs whose name is prefixed with the
  target type, if the build type and target type are different.

** AC_REQUIRE_AUX_FILE
  New trace macro that declares expected auxiliary files.

** AC_PROG_GREP
  New macro that tests for a grep program that accepts as a long a line
  as possible.

** AC_PROG_EGREP, AC_PROG_FGREP
  These macros now require AC_PROG_GREP, and try EGREP="$GREP -E" and
  FGREP="$GREP -F" respectively if possible, or else run a path search for
  a program that accepts as long a line as possible.

** AC_PROG_SED
  New macro that tests for a sed program that truncates as few characters
  as possible.

* Major changes in Autoconf 2.59

  Released 2003-11-04, by Akim Demaille

** ac_abs_builddir etc.
  Absolute file names were actually relative in 2.58.

* Major changes in Autoconf 2.58

  Released 2003-11-04, by Akim Demaille

** core.*
  core.* files are no longer removed, as they may be valid user files.

** autoreconf and auxiliary directory
  Autoreconf creates the auxiliary directory if needed.  This is
  especially useful for initial "bootstrapping" of fresh CVS checkouts.

** AC_CONFIG_MACRO_DIR
  Use this macro to declare the directory for local M4 macros for aclocal.

** AC_LIBOBJS
  No longer includes twice the same file in LIBOBJS if invoked
  multiple times.

** AC_CONFIG_COMMANDS
  The directory for its first argument is automatically created.  For
  instance, with

      AC_CONFIG_COMMANDS([src/modules.hh], [...])

  $top_builddir/src/ is created if needed.

** Autotest and local.at
  The optional file local.at is always included in Autotest test suites.

** Warnings
  The warnings are always issued, including with cached runs.
  This became a significant problem since aclocal and automake can
  run autoconf behind the scene.

** autoheader warnings
  The warnings of autoheader can be turned off, using --warning.
  For instance, -Wno-obsolete disables the complaints about acconfig.h
  and other deprecated constructs.

** New macros
  AC_C_RESTRICT, AC_INCLUDES_DEFAULT, AC_LANG_ASSERT, AC_LANG_WERROR,
  AS_SET_CATFILE.

** AC_DECL_SYS_SIGLIST
  Works again.

** AC_FUNC_MKTIME
  Now checks that mktime is the inverse of localtime.

** Improve DJGPP portability
  The Autoconf tools and configure behave better under DJGPP.

** Present But Cannot Be Compiled
  New FAQ section dedicated to the mystic

    configure: WARNING: pi.h: present but cannot be compiled
    configure: WARNING: pi.h: check for missing prerequisite headers?
    configure: WARNING: pi.h: proceeding with the preprocessor's result
      messages.

** Concurrent executions of autom4te
  autom4te now locks its internal files, which enables concurrent
  executions of autom4te, likely to happen if automake, autoconf,
  autoheader etc. are run simultaneously.

** Libtool
  Use of Libtool 1.5 and higher is encouraged.  Compatibility with
  Libtool pre-1.4 is not checked.

** Autotest
  Testsuites no longer rerun failed tests in verbose mode; instead,
  failures are logged while the test is run.

  In addition, expected failures can be marked as such.

* Major changes in Autoconf 2.57

  Released 2002-12-03 by Paul Eggert.

Bug fixes for problems with AIX linker, with freestanding C compilers,
with GNU M4 limitations, and with obsolete copies of GNU documents.

The Free Documentation License has been upgraded from 1.1 to 1.2.

* Major changes in Autoconf 2.56

  Released 2002-11-15 by Akim Demaille.

One packaging problem fixed (config/install-sh was not executable).

* Major changes in Autoconf 2.55

  Released 2002-11-14 by Akim Demaille.

Release tips:

           Have your configure.ac checked by autoscan ("autoscan").
             Try the warning options ("autoreconf -fv -Wall").

** Documentation

- AC_CHECK_HEADER, AC_CHECK_HEADERS
  More information on proper use.

- Writing Test Programs

  This sections explains how to write good test sources to use with