c.m4

autoconf是一个产生可以自动配置源代码包

    CXXFLAGS="-O2"
  else
    CXXFLAGS=
  fi
fi[]dnl
])# _AC_PROG_CXX_G


# AC_PROG_CXX_C_O
# ---------------
# Test if the C++ compiler accepts the options `-c' and `-o'
# simultaneously, and define `CXX_NO_MINUS_C_MINUS_O' if it does not.
AC_DEFUN([AC_PROG_CXX_C_O],
[AC_REQUIRE([AC_PROG_CXX])dnl
AC_LANG_PUSH([C++])dnl
AC_CACHE_CHECK([whether $CXX understands -c and -o together],
               [ac_cv_prog_cxx_c_o],
[AC_LANG_CONFTEST([AC_LANG_PROGRAM([])])
# We test twice because some compilers refuse to overwrite an existing
# `.o' file with `-o', although they will create one.
ac_try='$CXX $CXXFLAGS -c conftest.$ac_ext -o conftest2.$ac_objext >&AS_MESSAGE_LOG_FD'
rm -f conftest2.*
if _AC_DO_VAR(ac_try) &&
     test -f conftest2.$ac_objext &&
     _AC_DO_VAR(ac_try); then
  ac_cv_prog_cxx_c_o=yes
else
  ac_cv_prog_cxx_c_o=no
fi
rm -f conftest*])
if test $ac_cv_prog_cxx_c_o = no; then
  AC_DEFINE(CXX_NO_MINUS_C_MINUS_O, 1,
            [Define to 1 if your C++ compiler doesn't accept
             -c and -o together.])
fi
AC_LANG_POP([C++])dnl
])# AC_PROG_CXX_C_O


# ------------------------------ #
# 3d. The Objective C compiler.  #
# ------------------------------ #


# AC_LANG_PREPROC(Objective C)
# ----------------------------
# Find the Objective C preprocessor.  Must be AC_DEFUN'd to be AC_REQUIRE'able.
AC_DEFUN([AC_LANG_PREPROC(Objective C)],
[AC_REQUIRE([AC_PROG_OBJCPP])])


# AC_PROG_OBJCPP
# --------------
# Find a working Objective C preprocessor.
AC_DEFUN([AC_PROG_OBJCPP],
[AC_REQUIRE([AC_PROG_OBJC])dnl
AC_ARG_VAR([OBJCPP],   [Objective C preprocessor])dnl
_AC_ARG_VAR_CPPFLAGS()dnl
AC_LANG_PUSH(Objective C)dnl
AC_MSG_CHECKING([how to run the Objective C preprocessor])
if test -z "$OBJCPP"; then
  AC_CACHE_VAL(ac_cv_prog_OBJCPP,
  [dnl
    # Double quotes because OBJCPP needs to be expanded
    for OBJCPP in "$OBJC -E" "/lib/cpp"
    do
      _AC_PROG_PREPROC_WORKS_IFELSE([break])
    done
    ac_cv_prog_OBJCPP=$OBJCPP
  ])dnl
  OBJCPP=$ac_cv_prog_OBJCPP
else
  ac_cv_prog_OBJCPP=$OBJCPP
fi
AC_MSG_RESULT([$OBJCPP])
_AC_PROG_PREPROC_WORKS_IFELSE([],
	  [AC_MSG_FAILURE([Objective C preprocessor "$OBJCPP" fails sanity check])])
AC_SUBST(OBJCPP)dnl
AC_LANG_POP(Objective C)dnl
])# AC_PROG_OBJCPP


# AC_LANG_COMPILER(Objective C)
# -----------------------------
# Find the Objective C compiler.  Must be AC_DEFUN'd to be AC_REQUIRE'able.
AC_DEFUN([AC_LANG_COMPILER(Objective C)],
[AC_REQUIRE([AC_PROG_OBJC])])



# AC_PROG_OBJC([LIST-OF-COMPILERS])
# ---------------------------------
# LIST-OF-COMPILERS is a space separated list of Objective C compilers to
# search for (if not specified, a default list is used).  This just gives
# the user an opportunity to specify an alternative search list for the
# Objective C compiler.
# objcc StepStone Objective-C compiler (also "standard" name for OBJC)
# objc  David Stes' POC.  If you installed this, you likely want it.
# cc    Native C compiler (for instance, Apple).
# CC    You never know.
AN_MAKEVAR([OBJC],  [AC_PROG_OBJC])
AN_PROGRAM([objcc],  [AC_PROG_OBJC])
AN_PROGRAM([objc],  [AC_PROG_OBJC])
AC_DEFUN([AC_PROG_OBJC],
[AC_LANG_PUSH(Objective C)dnl
AC_ARG_VAR([OBJC],      [Objective C compiler command])dnl
AC_ARG_VAR([OBJCFLAGS], [Objective C compiler flags])dnl
_AC_ARG_VAR_LDFLAGS()dnl
_AC_ARG_VAR_CPPFLAGS()dnl
_AC_ARG_VAR_PRECIOUS([OBJC])dnl
AC_CHECK_TOOLS(OBJC,
	       [m4_default([$1], [gcc objcc objc cc CC])],
	       gcc)
# Provide some information about the compiler.
_AS_ECHO_LOG([checking for _AC_LANG compiler version])
ac_compiler=`set X $ac_compile; echo $[2]`
_AC_DO([$ac_compiler --version >&AS_MESSAGE_LOG_FD])
_AC_DO([$ac_compiler -v >&AS_MESSAGE_LOG_FD])
_AC_DO([$ac_compiler -V >&AS_MESSAGE_LOG_FD])

m4_expand_once([_AC_COMPILER_EXEEXT])[]dnl
m4_expand_once([_AC_COMPILER_OBJEXT])[]dnl
_AC_LANG_COMPILER_GNU
GOBJC=`test $ac_compiler_gnu = yes && echo yes`
_AC_PROG_OBJC_G
AC_LANG_POP(Objective C)dnl
])# AC_PROG_OBJC


# _AC_PROG_OBJC_G
# ---------------
# Check whether -g works, even if OBJCFLAGS is set, in case the package
# plays around with OBJCFLAGS (such as to build both debugging and
# normal versions of a library), tasteless as that idea is.
# Don't consider -g to work if it generates warnings when plain compiles don't.
m4_define([_AC_PROG_OBJC_G],
[ac_test_OBJCFLAGS=${OBJCFLAGS+set}
ac_save_OBJCFLAGS=$OBJCFLAGS
AC_CACHE_CHECK(whether $OBJC accepts -g, ac_cv_prog_objc_g,
  [ac_save_objc_werror_flag=$ac_objc_werror_flag
   ac_objc_werror_flag=yes
   ac_cv_prog_objc_g=no
   OBJCFLAGS="-g"
   _AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
     [ac_cv_prog_objc_g=yes],
     [OBJCFLAGS=""
      _AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[],
	[ac_objc_werror_flag=$ac_save_objc_werror_flag
	 OBJCFLAGS="-g"
	 _AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	   [ac_cv_prog_objc_g=yes])])])
   ac_objc_werror_flag=$ac_save_objc_werror_flag])
if test "$ac_test_OBJCFLAGS" = set; then
  OBJCFLAGS=$ac_save_OBJCFLAGS
elif test $ac_cv_prog_objc_g = yes; then
  if test "$GOBJC" = yes; then
    OBJCFLAGS="-g -O2"
  else
    OBJCFLAGS="-g"
  fi
else
  if test "$GOBJC" = yes; then
    OBJCFLAGS="-O2"
  else
    OBJCFLAGS=
  fi
fi[]dnl
])# _AC_PROG_OBJC_G






## ------------------------------- ##
## 4. Compilers' characteristics.  ##
## ------------------------------- ##


# -------------------------------- #
# 4b. C compiler characteristics.  #
# -------------------------------- #

# _AC_PROG_CC_C89 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# ----------------------------------------------------------------
# If the C compiler is not in ANSI C89 (ISO C90) mode by default, try
# to add an option to output variable CC to make it so.  This macro
# tries various options that select ANSI C89 on some system or
# another.  It considers the compiler to be in ANSI C89 mode if it
# handles function prototypes correctly.
AC_DEFUN([_AC_PROG_CC_C89],
[_AC_C_STD_TRY([c89],
[[#include <stdarg.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
/* Most of the following tests are stolen from RCS 5.7's src/conf.sh.  */
struct buf { int x; };
FILE * (*rcsopen) (struct buf *, struct stat *, int);
static char *e (p, i)
     char **p;
     int i;
{
  return p[i];
}
static char *f (char * (*g) (char **, int), char **p, ...)
{
  char *s;
  va_list v;
  va_start (v,p);
  s = g (p, va_arg (v,int));
  va_end (v);
  return s;
}

/* OSF 4.0 Compaq cc is some sort of almost-ANSI by default.  It has
   function prototypes and stuff, but not '\xHH' hex character constants.
   These don't provoke an error unfortunately, instead are silently treated
   as 'x'.  The following induces an error, until -std is added to get
   proper ANSI mode.  Curiously '\x00'!='x' always comes out true, for an
   array size at least.  It's necessary to write '\x00'==0 to get something
   that's true only with -std.  */
int osf4_cc_array ['\x00' == 0 ? 1 : -1];

/* IBM C 6 for AIX is almost-ANSI by default, but it replaces macro parameters
   inside strings and character constants.  */
#define FOO(x) 'x'
int xlc6_cc_array[FOO(a) == 'x' ? 1 : -1];

int test (int i, double x);
struct s1 {int (*f) (int a);};
struct s2 {int (*f) (double a);};
int pairnames (int, char **, FILE *(*)(struct buf *, struct stat *, int), int, int);
int argc;
char **argv;]],
[[return f (e, argv, 0) != argv[0]  ||  f (e, argv, 1) != argv[1];]],
dnl Don't try gcc -ansi; that turns off useful extensions and
dnl breaks some systems' header files.
dnl AIX circa 2003	-qlanglvl=extc89
dnl old AIX		-qlanglvl=ansi
dnl Ultrix, OSF/1, Tru64	-std
dnl HP-UX 10.20 and later	-Ae
dnl HP-UX older versions	-Aa -D_HPUX_SOURCE
dnl SVR4			-Xc -D__EXTENSIONS__
[-qlanglvl=extc89 -qlanglvl=ansi -std \
	-Ae "-Aa -D_HPUX_SOURCE" "-Xc -D__EXTENSIONS__"], [$1], [$2])[]dnl
])# _AC_PROG_CC_C89


# _AC_C_STD_TRY(STANDARD, TEST-PROLOGUE, TEST-BODY, OPTION-LIST,
#		ACTION-IF-AVAILABLE, ACTION-IF-UNAVAILABLE)
# --------------------------------------------------------------
# Check whether the C compiler accepts features of STANDARD (e.g `c89', `c99')
# by trying to compile a program of TEST-PROLOGUE and TEST-BODY.  If this fails,
# try again with each compiler option in the space-separated OPTION-LIST; if one
# helps, append it to CC.  If eventually successful, run ACTION-IF-AVAILABLE,
# else ACTION-IF-UNAVAILABLE.
AC_DEFUN([_AC_C_STD_TRY],
[AC_MSG_CHECKING([for $CC option to accept ISO ]m4_translit($1, [c], [C]))
AC_CACHE_VAL(ac_cv_prog_cc_$1,
[ac_cv_prog_cc_$1=no
ac_save_CC=$CC
AC_LANG_CONFTEST([AC_LANG_PROGRAM([$2], [$3])])
for ac_arg in '' $4
do
  CC="$ac_save_CC $ac_arg"
  _AC_COMPILE_IFELSE([], [ac_cv_prog_cc_$1=$ac_arg])
  test "x$ac_cv_prog_cc_$1" != "xno" && break
done
rm -f conftest.$ac_ext
CC=$ac_save_CC
])# AC_CACHE_VAL
case "x$ac_cv_prog_cc_$1" in
  x)
    AC_MSG_RESULT([none needed]) ;;
  xno)
    AC_MSG_RESULT([unsupported]) ;;
  *)
    CC="$CC $ac_cv_prog_cc_$1"
    AC_MSG_RESULT([$ac_cv_prog_cc_$1]) ;;
esac
AS_IF([test "x$ac_cv_prog_cc_$1" != xno], [$5], [$6])
])# _AC_C_STD_TRY


# _AC_PROG_CC_C99 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# ----------------------------------------------------------------
# If the C compiler is not in ISO C99 mode by default, try to add an
# option to output variable CC to make it so.  This macro tries
# various options that select ISO C99 on some system or another.  It
# considers the compiler to be in ISO C99 mode if it handles mixed
# code and declarations, _Bool, inline and restrict.
AC_DEFUN([_AC_PROG_CC_C99],
[_AC_C_STD_TRY([c99],
[[#include <stdarg.h>
#include <stdbool.h>
#include <stdlib.h>
#include <wchar.h>
#include <stdio.h>

struct incomplete_array
{
  int datasize;
  double data[];
};

struct named_init {
  int number;
  const wchar_t *name;
  double average;
};

typedef const char *ccp;

static inline int
test_restrict(ccp restrict text)
{
  // See if C++-style comments work.
  // Iterate through items via the restricted pointer.
  // Also check for declarations in for loops.
  for (unsigned int i = 0; *(text+i) != '\0'; ++i)
    continue;
  return 0;
}

// Check varargs and va_copy work.
static void
test_varargs(const char *format, ...)
{
  va_list args;
  va_start(args, format);
  va_list args_copy;
  va_copy(args_copy, args);

  const char *str;
  int number;
  float fnumber;

  while (*format)
    {
      switch (*format++)
	{
	case 's': // string
	  str = va_arg(args_copy, const char *);
	  break;
	case 'd': // int
	  number = va_arg(args_copy, int);
	  break;
	case 'f': // float
	  fnumber = (float) va_arg(args_copy, double);
	  break;
	default:
	  break;
	}
    }
  va_end(args_copy);
  va_end(args);
}
]],
[[
  // Check bool and long long datatypes.
  _Bool success = false;
  long long int bignum = -1234567890LL;
  unsigned long long int ubignum = 1234567890uLL;

  // Check restrict.
  if (test_restrict("String literal") != 0)
    success = true;
  char *restrict newvar = "Another string";

  // Check varargs.
  test_varargs("s, d' f .", "string", 65, 34.234);

  // Check incomplete arrays work.
  struct incomplete_array *ia =
    malloc(sizeof(struct incomplete_array) + (sizeof(double) * 10));
  ia->datasize = 10;
  for (int i = 0; i < ia->datasize; ++i)
    ia->data[i] = (double) i * 1.234;

  // Check named initialisers.
  struct named_init ni = {
    .number = 34,
    .name = L"Test wide string",
    .average = 543.34343,
  };

  ni.number = 58;

  int dynamic_array[ni.number];
  dynamic_array[43] = 543;

  // work around unused variable warnings
  return  bignum == 0LL || ubignum == 0uLL || newvar[0] == 'x';
]],
dnl Try
dnl GCC		-std=gnu99 (unused restrictive modes: -std=c99 -std=iso9899:1999)
dnl AIX		-qlanglvl=extc99 (unused restrictive mode: -qlanglvl=stdc99)
dnl Intel ICC	-c99
dnl IRIX	-c99
dnl Solaris	(unused because it causes the compiler to assume C99 semantics for
dnl		library functions, and this is invalid before Solaris 10: -xc99)
dnl Tru64	-c99
dnl with extended modes being tried first.
[[-std=gnu99 -c99 -qlanglvl=extc99]], [$1], [$2])[]dnl
])# _AC_PROG_CC_C99


# AC_PROG_CC_C89