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AX_EXT_CHECK_HEADER(<header>, <paths>).
Check for <header> with -I<path> for each path in <paths> if need be. The first sucecssful path is chosen (eg if you say AX_EXT_CHECK_HEADER(foo.h, bar baz qux) and -Ibaz works then -Iqux will not be tested.
Any -I flags that locate a header are added to CFLAGS and CPPFLAGS. AS with AC_CHECK_HEADERS it causes HAVE_<header>_H to be defined as 1.
Example:
AX_EXT_HAVE_HEADER(openssl/rsa.h, /usr/local/include /usr/local/ssl/include /usr/local/openssl/include)
Duncan Simpson <dps@simpson.demon.co.uk>
2005-01-21
AC_DEFUN([AX_EXT_HAVE_HEADER],
[AC_LANG_PUSH(C)
AC_CHECK_HEADER($1, [$3 got="yes"], [$4 got="no"], $5)
hdr=`echo $1 | $as_tr_sh`
for dir in $2; do
if test "x${got}" = "xno"; then
ext_hashdr_cvdir=`echo $dir | $as_tr_sh`
AC_CACHE_CHECK([for $1 library with -I$dir],
[ext_cv${ext_hashdr_cvdir}_hashdr_${hdr}],
[ext_have_hdr_save_cflags=${CFLAGS}
CFLAGS="${CFLAGS} -I${dir}"
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([#inc[]lude <$1>])],
[got="yes"; eval "ext_cv${ext_hashdr_cvdir}_hashdr_${hdr}"="yes"],
[got="no"; eval "ext_cv${ext_hashdr_cvdir}_hashdr_${hdr}"="no"])
CFLAGS=$ext_have_hdr_save_cflags])
if eval `echo 'test x${'ext_cv${ext_hashdr_cvdir}_hashdr_${hdr}'}' = "xyes"`; then
CFLAGS="${CFLAGS} -I${dir}"
CPPFLAGS="${CPPFLAGS} -I${dir}"
got="yes";
hdr=`echo $1 | $as_tr_cpp`
AC_DEFINE_UNQUOTED(HAVE_${hdr}, 1,
[Define this if you have the $1 header])
fi; fi; done
AC_LANG_POP])
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