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Obsolete Macros

Several macros are obsoleted in Autoconf, for various reasons (typically they failed to quote properly, couldn't be extended for more recent issues etc.). They are still supported, but deprecated: their use should be avoided.

During the jump from Autoconf version 1 to version 2, most of the macros were renamed to use a more uniform and descriptive naming scheme, but their signature did not change. See Macro Names, for a description of the new naming scheme. Below, there is just the mapping from old names to new names for these macros, the reader is invited to refer to the definition of the new macro for the signature and the description.

AC_ALLOCA Macro
AC_FUNC_ALLOCA

AC_ARG_ARRAY Macro
removed because of limited usefulness

AC_C_CROSS Macro
This macro is obsolete; it does nothing.

AC_CANONICAL_SYSTEM Macro
Determine the system type and set output variables to the names of the canonical system types. See Canonicalizing, for details about the variables this macro sets.

The user is encouraged to use either AC_CANONICAL_BUILD, or AC_CANONICAL_HOST, or AC_CANONICAL_TARGET, depending on the needs. Using AC_CANONICAL_TARGET is enough to run the two other macros.

AC_CHAR_UNSIGNED Macro
AC_C_CHAR_UNSIGNED

AC_CHECK_TYPE (type, default) Macro
Autoconf, up to 2.13, used to provide this version of AC_CHECK_TYPE, deprecated because of its flaws. Firstly, although it is a member of the CHECK clan, singular sub-family, it does more than just checking. Second, missing types are not typedef'd, they are #define'd, which can lead to incompatible code in the case of pointer types.

This use of AC_CHECK_TYPE is obsolete and discouraged, see Generic Types, for the description of the current macro.

If the type type is not defined, define it to be the C (or C++) builtin type default; e.g., short or unsigned.

This macro is equivalent to: 

AC_CHECK_TYPE([type],
              [AC_DEFINE([type], [default],
                         [Define to `default' if <sys/types.h>
                          does not define.])])

In order to keep backward compatibility, the two versions of AC_CHECK_TYPE are implemented, selected by a simple heuristics:

  1. If there are three or four arguments, the modern version is used.
  2. If the second argument appears to be a C or C++ type, then the obsolete version is used. This happens if the argument is a C or C++ builtin type or a C identifier ending in _t, optionally followed by one of [(* and then by a string of zero or more characters taken from the set []()* _a-zA-Z0-9.
  3. If the second argument is spelled with the alphabet of valid C and C++ types, the user is warned and the modern version is used.
  4. Otherwise, the modern version is used.

You are encouraged either to use a valid builtin type, or to use the equivalent modern code (see above), or better yet, to use AC_CHECK_TYPES together with 

#if !HAVE_LOFF_T
typedef loff_t off_t;
#endif

AC_CHECKING (feature-description) Macro
Same as AC_MSG_NOTICE([checking feature-description...].

AC_COMPILE_CHECK (echo-text, includes, function-body, action-if-found, [action-if-not-found]) Macro
This is an obsolete version of AC_TRY_LINK (see Examining Libraries), with the addition that it prints checking for echo-text to the standard output first, if echo-text is non-empty. Use AC_MSG_CHECKING and AC_MSG_RESULT instead to print messages (see Printing Messages).

AC_CONST Macro
AC_C_CONST

AC_CROSS_CHECK Macro
Same as AC_C_CROSS, which is obsolete too, and does nothing :-).

AC_CYGWIN Macro
Check for the Cygwin environment in which case the shell variable CYGWIN is set to yes. Don't use this macro, the dignified means to check the nature of the host is using AC_CANONICAL_HOST. As a matter of fact this macro is defined as: 
AC_REQUIRE([AC_CANONICAL_HOST])[]dnl
case $host_os in
  *cygwin* ) CYGWIN=yes;;
         * ) CYGWIN=no;;
esac

Beware that the variable CYGWIN has a very special meaning when running CygWin32, and should not be changed. That's yet another reason not to use this macro.

AC_DECL_YYTEXT Macro
Does nothing, now integrated in AC_PROG_LEX.

AC_DIR_HEADER Macro
Like calling AC_FUNC_CLOSEDIR_VOID andAC_HEADER_DIRENT, but defines a different set of C preprocessor macros to indicate which header file is found:

Header Old Symbol New Symbol
dirent.h DIRENT HAVE_DIRENT_H
sys/ndir.h SYSNDIR HAVE_SYS_NDIR_H
sys/dir.h SYSDIR HAVE_SYS_DIR_H
ndir.h NDIR HAVE_NDIR_H

AC_DYNIX_SEQ Macro
If on Dynix/PTX (Sequent UNIX), add -lseq to output variable LIBS. This macro used to be defined as 
AC_CHECK_LIB(seq, getmntent, LIBS="-lseq $LIBS")

now it is just AC_FUNC_GETMNTENT.

AC_EXEEXT Macro
Defined the output variable EXEEXT based on the output of the compiler, which is now done automatically. Typically set to empty string if Unix and .exe if Win32 or OS/2.

AC_EMXOS2 Macro
Similar to AC_CYGWIN but checks for the EMX environment on OS/2 and sets EMXOS2.

AC_ERROR Macro
AC_MSG_ERROR

AC_FIND_X Macro
AC_PATH_X

AC_FIND_XTRA Macro
AC_PATH_XTRA

AC_FUNC_CHECK Macro
AC_CHECK_FUNC

AC_FUNC_WAIT3 Macro
If wait3 is found and fills in the contents of its third argument (a struct rusage *), which HP-UX does not do, define HAVE_WAIT3.

These days portable programs should use waitpid, not wait3, as wait3 is being removed from the Open Group standards, and will not appear in the next revision of POSIX.

AC_GCC_TRADITIONAL Macro
AC_PROG_GCC_TRADITIONAL

AC_GETGROUPS_T Macro
AC_TYPE_GETGROUPS

AC_GETLOADAVG Macro
AC_FUNC_GETLOADAVG

AC_HAVE_FUNCS Macro
AC_CHECK_FUNCS

AC_HAVE_HEADERS Macro
AC_CHECK_HEADERS

AC_HAVE_LIBRARY (library, [action-if-found], [action-if-not-found], [other-libraries]) Macro
This macro is equivalent to calling AC_CHECK_LIB with a function argument of main. In addition, library can be written as any of foo, -lfoo, or libfoo.a. In all of those cases, the compiler is passed -lfoo. However, library cannot be a shell variable; it must be a literal name.

AC_HAVE_POUNDBANG Macro
AC_SYS_INTERPRETER (different calling convention)

AC_HEADER_CHECK Macro
AC_CHECK_HEADER

AC_HEADER_EGREP Macro
AC_EGREP_HEADER

AC_INIT (unique-file-in-source-dir) Macro
Formerly AC_INIT used to have a single argument, and was equivalent to: 
AC_INIT
AC_CONFIG_SRCDIR(unique-file-in-source-dir)

AC_INLINE Macro
AC_C_INLINE

AC_INT_16_BITS Macro
If the C type int is 16 bits wide, define INT_16_BITS. Use AC_CHECK_SIZEOF(int) instead.

AC_IRIX_SUN Macro
If on IRIX (Silicon Graphics UNIX), add -lsun to output LIBS. If you were using it to get getmntent, use AC_FUNC_GETMNTENT instead. If you used it for the NIS versions of the password and group functions, use AC_CHECK_LIB(sun, getpwnam). Up to Autoconf 2.13, it used to be 
AC_CHECK_LIB(sun, getmntent, LIBS="-lsun $LIBS")

now it is defined as 

AC_FUNC_GETMNTENT
AC_CHECK_LIB(sun, getpwnam)

AC_LANG_C Macro
Same as AC_LANG(C).

AC_LANG_CPLUSPLUS Macro
Same as AC_LANG(C++).

AC_LANG_FORTRAN77 Macro
Same as AC_LANG(Fortran 77).

AC_LANG_RESTORE Macro
Select the language that is saved on the top of the stack, as set by AC_LANG_SAVE, remove it from the stack, and call AC_LANG(language).

AC_LANG_SAVE Macro
Remember the current language (as set by AC_LANG) on a stack. The current language does not change. AC_LANG_PUSH is preferred.

AC_LINK_FILES (source..., dest...) Macro
This is an obsolete version of AC_CONFIG_LINKS. An updated version of: 
AC_LINK_FILES(config/$machine.h config/$obj_format.h,
              host.h            object.h)

is: 

AC_CONFIG_LINKS(host.h:config/$machine.h
                object.h:config/$obj_format.h)

AC_LN_S Macro
AC_PROG_LN_S

AC_LONG_64_BITS Macro
Define LONG_64_BITS if the C type long int is 64 bits wide. Use the generic macro AC_CHECK_SIZEOF([long int]) instead.

AC_LONG_DOUBLE Macro
AC_C_LONG_DOUBLE

AC_LONG_FILE_NAMES Macro
AC_SYS_LONG_FILE_NAMES

AC_MAJOR_HEADER Macro
AC_HEADER_MAJOR

AC_MEMORY_H Macro
Used to define NEED_MEMORY_H if the mem functions were defined in memory.h. Today it is equivalent to AC_CHECK_HEADERS(memory.h). Adjust your code to depend upon HAVE_MEMORY_H, not NEED_MEMORY_H, see See Standard Symbols.

AC_MINGW32 Macro
Similar to AC_CYGWIN but checks for the MingW32 compiler environment and sets MINGW32.

AC_MINUS_C_MINUS_O Macro
AC_PROG_CC_C_O

AC_MMAP Macro
AC_FUNC_MMAP

AC_MODE_T Macro
AC_TYPE_MODE_T

AC_OBJEXT Macro
Defined the output variable OBJEXT based on the output of the compiler, after .c files have been excluded. Typically set to o if Unix, obj if Win32. Now the compiler checking macros handle this automatically.

AC_OBSOLETE (this-macro-name, [suggestion]) Macro
Make m4 print a message to the standard error output warning that this-macro-name is obsolete, and giving the file and line number where it was called. this-macro-name should be the name of the macro that is calling AC_OBSOLETE. If suggestion is given, it is printed at the end of the warning message; for example, it can be a suggestion for what to use instead of this-macro-name.

For instance 

AC_OBSOLETE([$0], [; use AC_CHECK_HEADERS(unistd.h) instead])dnl

You are encouraged to use AU_DEFUN instead, since it gives better services to the user.

AC_OFF_T Macro
AC_TYPE_OFF_T

AC_OUTPUT ([file]..., [extra-cmds], [init-cmds]) Macro
The use of AC_OUTPUT with argument is deprecated, this obsoleted interface is equivalent to: 
AC_CONFIG_FILES(file...)
AC_CONFIG_COMMANDS([default],
                   extra-cmds, init-cmds)
AC_OUTPUT

AC_OUTPUT_COMMANDS (extra-cmds, [init-cmds]) Macro
Specify additional shell commands to run at the end of config.status, and shell commands to initialize any variables from configure. This macro may be called multiple times. It is obsolete, replaced by AC_CONFIG_COMMANDS.

Here is an unrealistic example: 

fubar=27
AC_OUTPUT_COMMANDS([echo this is extra $fubar, and so on.],
                   [fubar=$fubar])
AC_OUTPUT_COMMANDS([echo this is another, extra, bit],
                   [echo init bit])

Aside from the fact that AC_CONFIG_COMMANDS requires an additional key, an important difference is that AC_OUTPUT_COMMANDS is quoting its arguments twice, while AC_CONFIG_COMMANDS. This means that AC_CONFIG_COMMANDS can safely be given macro calls as arguments: 

AC_CONFIG_COMMANDS(foo, [my_FOO()])

conversely, where one level of quoting was enough for literal strings with AC_OUTPUT_COMMANDS, you need two with AC_CONFIG_COMMANDS. The following lines are equivalent: 

AC_OUTPUT_COMMANDS([echo "Square brackets: []"])
AC_CONFIG_COMMANDS([default], [[echo "Square brackets: []"]])

AC_PID_T Macro
AC_TYPE_PID_T

AC_PREFIX Macro
AC_PREFIX_PROGRAM

AC_PROGRAMS_CHECK Macro
AC_CHECK_PROGS

AC_PROGRAMS_PATH Macro
AC_PATH_PROGS

AC_PROGRAM_CHECK Macro
AC_CHECK_PROG

AC_PROGRAM_EGREP Macro
AC_EGREP_CPP

AC_PROGRAM_PATH Macro
AC_PATH_PROG

AC_REMOTE_TAPE Macro
removed because of limited usefulness

AC_RESTARTABLE_SYSCALLS Macro
AC_SYS_RESTARTABLE_SYSCALLS

AC_RETSIGTYPE Macro
AC_TYPE_SIGNAL

AC_RSH Macro
Removed because of limited usefulness.

AC_SCO_INTL Macro
If on SCO UNIX, add -lintl to output variable LIBS. This macro used to 
AC_CHECK_LIB(intl, strftime, LIBS="-lintl $LIBS")

now it just calls AC_FUNC_STRFTIME instead.

AC_SETVBUF_REVERSED Macro
AC_FUNC_SETVBUF_REVERSED

AC_SET_MAKE Macro
AC_PROG_MAKE_SET

AC_SIZEOF_TYPE Macro
AC_CHECK_SIZEOF

AC_SIZE_T Macro
AC_TYPE_SIZE_T

AC_STAT_MACROS_BROKEN Macro
AC_HEADER_STAT

AC_STDC_HEADERS Macro
AC_HEADER_STDC

AC_STRCOLL Macro
AC_FUNC_STRCOLL

AC_ST_BLKSIZE Macro
AC_STRUCT_ST_BLKSIZE

AC_ST_BLOCKS Macro
AC_STRUCT_ST_BLOCKS

AC_ST_RDEV Macro
AC_STRUCT_ST_RDEV

AC_SYS_RESTARTABLE_SYSCALLS Macro
If the system automatically restarts a system call that is interrupted by a signal, define HAVE_RESTARTABLE_SYSCALLS. This macro does not check if system calls are restarted in general-it tests whether a signal handler installed with signal (but not sigaction) causes system calls to be restarted. It does not test if system calls can be restarted when interrupted by signals that have no handler.

These days portable programs should use sigaction with SA_RESTART if they want restartable system calls. They should not rely on HAVE_RESTARTABLE_SYSCALLS, since nowadays whether a system call is restartable is a dynamic issue, not a configuration-time issue.

AC_SYS_SIGLIST_DECLARED Macro
AC_DECL_SYS_SIGLIST

AC_TEST_CPP Macro
AC_TRY_CPP

AC_TEST_PROGRAM Macro
AC_TRY_RUN

AC_TIMEZONE Macro
AC_STRUCT_TIMEZONE

AC_TIME_WITH_SYS_TIME Macro
AC_HEADER_TIME

AC_UID_T Macro
AC_TYPE_UID_T

AC_UNISTD_H Macro
Same as AC_CHECK_HEADERS(unistd.h).

AC_USG Macro
Define USG if the BSD string functions are defined in strings.h. You should no longer depend upon USG, but on HAVE_STRING_H, see See Standard Symbols.

AC_UTIME_NULL Macro
AC_FUNC_UTIME_NULL

AC_VALIDATE_CACHED_SYSTEM_TUPLE ([cmd]) Macro
If the cache file is inconsistent with the current host, target and build system types, it used to execute cmd or print a default error message.

This is now handled by default.

AC_VERBOSE (result-description) Macro
AC_MSG_RESULT.

AC_VFORK Macro
AC_FUNC_VFORK

AC_VPRINTF Macro
AC_FUNC_VPRINTF

AC_WAIT3 Macro
AC_FUNC_WAIT3

AC_WARN Macro
AC_MSG_WARN

AC_WORDS_BIGENDIAN Macro
AC_C_BIGENDIAN

AC_XENIX_DIR Macro
This macro used to add -lx to output variable LIBS if on Xenix. Also, if dirent.h is being checked for, added -ldir to LIBS. Now it is merely an alias of AC_HEADER_DIRENT instead, plus some code to detect whether running XENIX on which you should not depend: 
AC_MSG_CHECKING([for Xenix])
AC_EGREP_CPP(yes,
[#if defined M_XENIX && !defined M_UNIX
  yes
#endif],
             [AC_MSG_RESULT([yes]); XENIX=yes],
             [AC_MSG_RESULT([no]); XENIX=])

AC_YYTEXT_POINTER Macro
AC_DECL_YYTEXT