#							-*- autoconf -*-

AT_BANNER([Low level compiling/preprocessing macros.])

# Since the macros which compile are required by most tests, check
# them first.  But remember that looking for a compiler is even more
# primitive, so check those first.


## ------------ ##
## C keywords.  ##
## ------------ ##

# GCC supports `const', `volatile', and `inline'.
AT_CHECK_MACRO([C keywords],
[[AC_PROG_CC
AC_C_CONST
AC_C_INLINE
AC_C_VOLATILE
case "$GCC,$ac_cv_c_const,$ac_cv_c_inline,$ac_cv_c_volatile" in
 yes,*no*)
   AC_MSG_ERROR([failed to detect `const', `inline' or `volatile' support]);;
esac]])



## --------------------------- ##
## AC_PROG_CPP with warnings.  ##
## --------------------------- ##


# It's Ok for strict preprocessors to produce warnings.

AT_SETUP([AC_PROG_CPP with warnings])

AT_DATA([mycpp],
[[#! /bin/sh
echo noise >&2
exec ${1+"$@"}
]])

chmod +x mycpp

_AT_CHECK_AC_MACRO(
[AC_PROG_CPP
# If the preprocessor is not strict, just ignore
test "x$ac_c_preproc_warn_flag" = xyes &&
  AC_MSG_ERROR([preprocessor has no warning option], 77)
CPP="./mycpp $CPP"
AC_CHECK_HEADERS(stdio.h autoconf_io.h)])

AT_CHECK_DEFINES(
[/* #undef HAVE_AUTOCONF_IO_H */
#define HAVE_STDIO_H 1
])

AT_CLEANUP(configure config.status config.log config.cache config.hin config.h env-after)dnl


## ------------------------------ ##
## AC_PROG_CPP without warnings.  ##
## ------------------------------ ##

AT_SETUP([AC_PROG_CPP without warnings])

AT_DATA([mycpp],
[[#! /bin/sh
/lib/cpp ${1+"$@"}
exit 0
]])

chmod +x mycpp

_AT_CHECK_AC_MACRO(
[# Ignore if /lib/cpp doesn't work
/lib/cpp </dev/null >/dev/null 2>&1 ||
  AC_MSG_ERROR([preprocessor doesn't work], 77)
CPP=./mycpp
AC_PROG_CPP
test "x$ac_c_preproc_warn_flag" != xyes &&
  AC_MSG_ERROR([failed to detect preprocessor warning option])
AC_CHECK_HEADERS(stdio.h autoconf_io.h)])

AT_CHECK_DEFINES(
[/* #undef HAVE_AUTOCONF_IO_H */
#define HAVE_STDIO_H 1
])

AT_CLEANUP(configure config.status config.log config.cache config.hin config.h env-after)dnl



## ------------------ ##
## AC_TRY_LINK_FUNC.  ##
## ------------------ ##

AT_CHECK_MACRO([AC_TRY_LINK_FUNC],
[AC_TRY_LINK_FUNC(exit,,
                  [AC_MSG_ERROR([cannot find `exit'])])
AC_TRY_LINK_FUNC(Be_doomed_if_your_libc_has_a_function_named_like_this,
                 [AC_MSG_ERROR([found a nonexistent function])])])