general.m4

libiconv是一个很不错的字符集转换库。程序接口也很简单

dnl Copyright (C) 1993-2003 Free Software Foundation, Inc.
dnl This file is free software, distributed under the terms of the GNU
dnl General Public License.  As a special exception to the GNU General
dnl Public License, this file may be distributed as part of a program
dnl that contains a configuration script generated by Autoconf, under
dnl the same distribution terms as the rest of that program.

dnl From Bruno Haible, Marcus Daniels, Sam Steingold.

AC_PREREQ(2.13)

dnl without AC_MSG_...:   with AC_MSG_... and caching:
dnl   AC_TRY_CPP          CL_CPP_CHECK
dnl   AC_TRY_COMPILE      CL_COMPILE_CHECK
dnl   AC_TRY_LINK         CL_LINK_CHECK
dnl   AC_TRY_RUN          CL_RUN_CHECK - would require cross-compiling support
dnl Usage:
dnl AC_TRY_CPP(INCLUDES,
dnl            ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND])
dnl CL_CPP_CHECK(ECHO-TEXT, CACHE-ID,
dnl              INCLUDES,
dnl              ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND])
dnl AC_TRY_xxx(INCLUDES, FUNCTION-BODY,
dnl            ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND])
dnl CL_xxx_CHECK(ECHO-TEXT, CACHE-ID,
dnl              INCLUDES, FUNCTION-BODY,
dnl              ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND])

AC_DEFUN([CL_CPP_CHECK],
[AC_MSG_CHECKING(for $1)
AC_CACHE_VAL($2,[
AC_TRY_CPP([$3], $2=yes, $2=no)
])
AC_MSG_RESULT([$]$2)
if test [$]$2 = yes; then
  ifelse([$4], , :, [$4])
ifelse([$5], , , [else
  $5
])dnl
fi
])

AC_DEFUN([CL_COMPILE_CHECK],
[AC_MSG_CHECKING(for $1)
AC_CACHE_VAL($2,[
AC_TRY_COMPILE([$3],[$4], $2=yes, $2=no)
])
AC_MSG_RESULT([$]$2)
if test [$]$2 = yes; then
  ifelse([$5], , :, [$5])
ifelse([$6], , , [else
  $6
])dnl
fi
])

AC_DEFUN([CL_LINK_CHECK],
[AC_MSG_CHECKING(for $1)
AC_CACHE_VAL($2,[
AC_TRY_LINK([$3],[$4], $2=yes, $2=no)
])
AC_MSG_RESULT([$]$2)
if test [$]$2 = yes; then
  ifelse([$5], , :, [$5])
ifelse([$6], , , [else
  $6
])dnl
fi
])

dnl CL_SILENT(ACTION)
dnl performs ACTION, with AC_MSG_CHECKING and AC_MSG_RESULT being defined away.
AC_DEFUN([CL_SILENT],
[pushdef([AC_MSG_CHECKING],[:])dnl
pushdef([AC_CHECKING],[:])dnl
pushdef([AC_MSG_RESULT],[:])dnl
$1[]dnl
popdef([AC_MSG_RESULT])dnl
popdef([AC_CHECKING])dnl
popdef([AC_MSG_CHECKING])dnl
])

dnl Expands to the "extern ..." prefix used for system declarations.
dnl AC_LANG_EXTERN()
AC_DEFUN([AC_LANG_EXTERN],
[extern
#ifdef __cplusplus
"C"
#endif
])

AC_DEFUN([CL_CC_WORKS],
[AC_CACHE_CHECK(whether CC works at all, cl_cv_prog_cc_works, [
AC_LANG_SAVE()
AC_LANG_C()
AC_TRY_RUN([int main() { exit(0); }],
cl_cv_prog_cc_works=yes, cl_cv_prog_cc_works=no,
AC_TRY_LINK([], [], cl_cv_prog_cc_works=yes, cl_cv_prog_cc_works=no))
AC_LANG_RESTORE()
])
case "$cl_cv_prog_cc_works" in
  *no) echo "Installation or configuration problem: C compiler cannot create executables."; exit 1;;
  *yes) ;;
esac
])