Build: Leave LIBS alone during configure

[libsigrok.git] / m4 / sigrok.m4

diff --git a/m4/sigrok.m4 b/m4/sigrok.m4
index 875bd1633cf4998c329d2695a135b21dedb00b3a..30d87800577494e9476c581efa47437e2dcc5cf4 100644 (file)
--- a/m4/sigrok.m4
+++ b/m4/sigrok.m4
@@ -16,7 +16,7 @@
 ## You should have received a copy of the GNU General Public License
 ## along with sigrok. If not, see <http://www.gnu.org/licenses/>.
 
-#serial 20150823
+#serial 20150824
 
 ## SR_APPEND(var-name, [list-sep,] element)
 ##
@@ -31,6 +31,19 @@ m4_assert([$# >= 2])[]dnl
 $1=[$]{$1[}]m4_if([$#], [2], [[$]{$1:+' '}$2], [[$]{$1:+$2}$3])[]dnl
 ])
 
+## SR_PREPEND(var-name, [list-sep,] element)
+##
+## Prepend the shell word <element> to the shell variable named <var-name>,
+## suffixed by <list-sep> unless the list was empty before prepending. If
+## only two arguments are supplied, <list-sep> defaults to a single space
+## character.
+##
+AC_DEFUN([SR_PREPEND],
+[dnl
+m4_assert([$# >= 2])[]dnl
+$1=m4_if([$#], [2], [$2[$]{$1:+' '}], [$3[$]{$1:+$2}])[$]$1[]dnl
+])
+
 ## _SR_PKG_VERSION_SET(var-prefix, pkg-name, tag-prefix, base-version, major, minor, [micro])
 ##
 m4_define([_SR_PKG_VERSION_SET],
@@ -115,6 +128,24 @@ _SR_LIB_VERSION_SET([$1],
        [$2], m4_unquote(m4_split([$2], [:])))
 ])
 
+## SR_SEARCH_LIBS(libs-var, function, search-libs,
+##                [action-if-found], [action-if-not-found], [other-libs])
+##
+## Same as AC_SEARCH_LIBS, except that the result is prepended
+## to <libs-var> instead of LIBS. Calls AC_SUBST on <libs-var>.
+##
+AC_DEFUN([SR_SEARCH_LIBS],
+[dnl
+m4_assert([$# >= 3])[]dnl
+sr_sl_save_LIBS=$LIBS
+AC_SEARCH_LIBS([$2], [$3],,, m4_join([$6], [[$]$1]))
+LIBS=$sr_sl_save_LIBS
+AS_CASE([$ac_cv_search_$2], [no*],,
+       [SR_PREPEND([$1], [$ac_cv_search_$2])])
+m4_ifvaln([$4$5], [AS_IF([test "x$ac_cv_search_$2" = xno], [$5], [$4])])[]dnl
+AC_SUBST([$1])[]dnl
+])
+
 ## _SR_VAR_SUMMARY(tag, var-name, line-leader, align-columns, align-char)
 ##
 m4_define([_SR_VAR_SUMMARY], [dnl