diff --git a/ChangeLog b/ChangeLog
index 2ffe2c91e..cb0ee1d84 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-06-30  Richard Frith-Macdonald <rfm@gnu.org>
+
+        * configure.ac:
+        * configure:
+        * Headers/GNUstepBase/config.h.in:
+        Add test for pthread_mutex_t.__data.__owner
+        Update various tests to silence autoconf warnings.
+
 2015-06-26 Riccardo Mottola <rm@gnu.org>
 
 	* Source/NSMethodSignature.m
diff --git a/Headers/GNUstepBase/config.h.in b/Headers/GNUstepBase/config.h.in
index 782389d0e..d0915d1ae 100644
--- a/Headers/GNUstepBase/config.h.in
+++ b/Headers/GNUstepBase/config.h.in
@@ -467,6 +467,9 @@
 /* Define to 1 if you have the `pthread_main_np' function. */
 #undef HAVE_PTHREAD_MAIN_NP
 
+/* Define if you have pthread_mutex_t.__data.__owner */
+#undef HAVE_PTHREAD_MUTEX_OWNER
+
 /* Define to 1 if you have the <pthread_np.h> header file. */
 #undef HAVE_PTHREAD_NP_H
 
diff --git a/configure b/configure
index b024f89c5..8eca83812 100755
--- a/configure
+++ b/configure
@@ -6150,6 +6150,9 @@ elif test "$OBJC_RUNTIME_LIB" = "gnugc"; then
 $as_echo "GNU" >&6; }
   OBJCFLAGS="$OBJCFLAGS -fgnu-runtime"
   OBJC_WITH_GC=yes
+elif test "$OBJC_RUNTIME_LIB" = "ng"; then
+  { $as_echo "$as_me:$LINENO: result: Next Gen" >&5
+$as_echo "Next Gen" >&6; }
 else
   { $as_echo "$as_me:$LINENO: result: GNU" >&5
 $as_echo "GNU" >&6; }
@@ -7156,6 +7159,11 @@ $as_echo_n "checking for gcc visibility attribute support... " >&6; }
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Werror"
 cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 
   #include <stdio.h>
   int foo() __attribute__ ((visibility("internal")));
@@ -12155,6 +12163,116 @@ $as_echo "$as_me: error: Unable to find size of pthread_mutex_t (required)." >&2
    { (exit 1); exit 1; }; }
   fi
 
+# pthread_mutex_t.__data.__owner is non-standard since pthread_mutex_t is
+# nominally an opaque type.  We must not rely on this for anything other
+# than debug output!
+  { $as_echo "$as_me:$LINENO: checking for pthread_mutex_t.__data.__owner" >&5
+$as_echo_n "checking for pthread_mutex_t.__data.__owner... " >&6; }
+if test "${ac_cv_member_pthread_mutex_t___data___owner+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+#include <pthread.h>
+
+int
+main ()
+{
+static pthread_mutex_t ac_aggr;
+if (ac_aggr.__data.__owner)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv_member_pthread_mutex_t___data___owner=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+#include <pthread.h>
+
+int
+main ()
+{
+static pthread_mutex_t ac_aggr;
+if (sizeof ac_aggr.__data.__owner)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv_member_pthread_mutex_t___data___owner=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv_member_pthread_mutex_t___data___owner=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:$LINENO: result: $ac_cv_member_pthread_mutex_t___data___owner" >&5
+$as_echo "$ac_cv_member_pthread_mutex_t___data___owner" >&6; }
+
+  if test $ac_cv_member_pthread_mutex_t___data___owner = yes ; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_PTHREAD_MUTEX_OWNER 1
+_ACEOF
+
+  fi
   # The cast to long int works around a bug in the HP C Compiler
 # version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
 # declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'.
@@ -13874,6 +13992,11 @@ $as_echo_n "checking for objc_root_class attribute support... " >&6; }
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Werror $OBJCFLAGS -x objective-c"
 cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 
   __attribute__((objc_root_class)) @interface RootObject
   @end
@@ -14895,6 +15018,11 @@ $as_echo_n "checking for non-fragile-abi support... " >&6; }
   non_fragile="$cross_non_fragile"
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.non-fragile-ivars.m"
 _ACEOF
 rm -f conftest$ac_exeext
@@ -15019,6 +15147,11 @@ fi
 { $as_echo "$as_me:$LINENO: checking for objc_setUncaughtExceptionHandler() in runtime" >&5
 $as_echo_n "checking for objc_setUncaughtExceptionHandler() in runtime... " >&6; }
 cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.setUncaughtExceptionHandler.m"
 _ACEOF
 rm -f conftest.$ac_objext conftest$ac_exeext
@@ -15068,6 +15201,11 @@ $as_echo "$have_set_uncaught_exception_handler" >&6; }
 { $as_echo "$as_me:$LINENO: checking for objc_set_unexpected() in runtime" >&5
 $as_echo_n "checking for objc_set_unexpected() in runtime... " >&6; }
 cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.set_unexpected.m"
 _ACEOF
 rm -f conftest.$ac_objext conftest$ac_exeext
@@ -15120,6 +15258,11 @@ if test "$cross_compiling" = yes; then
   have_unexpected="$cross_have_unexpected"
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.unexpected.m"
 _ACEOF
 rm -f conftest$ac_exeext
@@ -15321,6 +15464,11 @@ if test "$cross_compiling" = yes; then
   safe_initialize="$cross_safe_initialize"
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.initialize.m"
 _ACEOF
 rm -f conftest$ac_exeext
@@ -24259,6 +24407,11 @@ CPPFLAGS="$CPPFLAGS $OBJCFLAGS -x objective-c"
 { $as_echo "$as_me:$LINENO: checking for forwarding callback in runtime" >&5
 $as_echo_n "checking for forwarding callback in runtime... " >&6; }
 cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.forward2.m"
 _ACEOF
 rm -f conftest.$ac_objext
@@ -24296,6 +24449,11 @@ _ACEOF
 
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.forward.m"
 _ACEOF
 rm -f conftest.$ac_objext
@@ -24582,6 +24740,11 @@ $as_echo_n "checking if ffcall trampolines work... " >&6; }
   have_working_trampoline=yes
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include "$srcdir/config/config.trampoline.c"
 _ACEOF
 rm -f conftest$ac_exeext
@@ -24697,6 +24860,11 @@ if test "$cross_compiling" = yes; then
   found_iconv="$cross_found_iconv_libc"
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include <iconv.h>
 int main(int argc,char **argv)
 { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }
@@ -24784,6 +24952,11 @@ esac
 
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include <iconv.h>
   int main(int argc,char **argv)
   { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }
@@ -24851,6 +25024,11 @@ if test $found_iconv = no ; then
 
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include <giconv.h>
   int main(int argc,char **argv)
   { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }
@@ -24929,6 +25107,11 @@ See \`config.log' for more details." >&2;}
    { (exit 1); exit 1; }; }; }
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include <iconv.h>
 int main(int argc,char **argv)
 { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }
@@ -25018,6 +25201,11 @@ See \`config.log' for more details." >&2;}
    { (exit 1); exit 1; }; }; }
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include <iconv.h>
   int main(int argc,char **argv)
   { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }
@@ -25087,6 +25275,11 @@ See \`config.log' for more details." >&2;}
    { (exit 1); exit 1; }; }; }
 else
   cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
 #include <giconv.h>
   int main(int argc,char **argv)
   { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }
diff --git a/configure.ac b/configure.ac
index 9cd3b2502..4a47b7b1a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1346,11 +1346,11 @@ fi
 AC_MSG_CHECKING(for gcc visibility attribute support)
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Werror"
-AC_COMPILE_IFELSE([
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([
   #include <stdio.h>
   int foo() __attribute__ ((visibility("internal")));
   int foo(){ return 1; }
-  int main(){ return foo(); }],
+  int main(){ return foo(); }])],
   AC_MSG_RESULT([found])
   gs_visibility=1,
   AC_MSG_RESULT([not present])
@@ -1673,6 +1673,15 @@ if test $ac_cv_header_pthread_h = yes ; then
     AC_MSG_ERROR([Unable to find size of pthread_mutex_t (required).])
   fi
   AC_SUBST(GS_SIZEOF_MUTEX_T)
+# pthread_mutex_t.__data.__owner is non-standard since pthread_mutex_t is
+# nominally an opaque type.  We must not rely on this for anything other
+# than debug output!
+  AC_CHECK_MEMBER([pthread_mutex_t.__data.__owner],,,[AC_INCLUDES_DEFAULT
+#include <pthread.h>])
+  if test $ac_cv_member_pthread_mutex_t___data___owner = yes ; then
+    AC_DEFINE(HAVE_PTHREAD_MUTEX_OWNER, 1,
+      [Define if you have pthread_mutex_t.__data.__owner])
+  fi
   AC_CHECK_SIZEOF(pthread_cond_t,,[AC_INCLUDES_DEFAULT
 #include <pthread.h>])
   if test $ac_cv_sizeof_pthread_cond_t = 0 ; then
@@ -1742,11 +1751,11 @@ AC_CHECK_FUNCS(nanosleep usleep Sleep)
 AC_MSG_CHECKING(for objc_root_class attribute support)
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Werror $OBJCFLAGS -x objective-c"
-AC_COMPILE_IFELSE([
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([
   __attribute__((objc_root_class)) @interface RootObject
   @end
   @implementation RootObject
-  @end],
+  @end])],
   AC_MSG_RESULT([found])
   gs_objc_root_class_attr=1,
   AC_MSG_RESULT([not present])
@@ -1966,7 +1975,8 @@ if test "$nonfragile" = "yes"; then
   saved_CPPFLAGS="$CPPFLAGS"
   CPPFLAGS="$CPPFLAGS $OBJCFLAGS -fobjc-nonfragile-abi -x objective-c"
   AC_MSG_CHECKING(for non-fragile-abi support)
-  AC_RUN_IFELSE([#include "$srcdir/config/config.non-fragile-ivars.m"],
+  AC_RUN_IFELSE([AC_LANG_SOURCE(
+    [[#include "$srcdir/config/config.non-fragile-ivars.m"]])],
     non_fragile=yes, non_fragile=no,
     non_fragile="$cross_non_fragile")
   CPPFLAGS="$saved_CPPFLAGS"
@@ -2034,7 +2044,8 @@ fi
 # the other hand, that case is going to become more and more unusual.
 
 AC_MSG_CHECKING(for objc_setUncaughtExceptionHandler() in runtime)
-AC_LINK_IFELSE([#include "$srcdir/config/config.setUncaughtExceptionHandler.m"],
+AC_LINK_IFELSE([AC_LANG_SOURCE(
+  [[#include "$srcdir/config/config.setUncaughtExceptionHandler.m"]])],
 	have_set_uncaught_exception_handler=yes, have_set_uncaught_exception_handler=no)
 if test $have_set_uncaught_exception_handler = yes; then
   AC_DEFINE(HAVE_SET_UNCAUGHT_EXCEPTION_HANDLER,1,
@@ -2045,7 +2056,8 @@ AC_MSG_RESULT($have_set_uncaught_exception_handler)
 # Don't revert any Objective-C flags as they are used in the next test
 
 AC_MSG_CHECKING(for objc_set_unexpected() in runtime)
-AC_LINK_IFELSE([#include "$srcdir/config/config.set_unexpected.m"],
+AC_LINK_IFELSE(
+  [AC_LANG_SOURCE([[#include "$srcdir/config/config.set_unexpected.m"]])],
 	have_set_unexpected=yes, have_set_unexpected=no)
 if test $have_set_unexpected = yes; then
   AC_DEFINE(HAVE_SET_UNEXPECTED,1,
@@ -2056,8 +2068,11 @@ AC_MSG_RESULT($have_set_unexpected)
 # Don't revert any Objective-C flags as they are used in the next test
 
 AC_MSG_CHECKING(for _objc_unexpected_exception in runtime)
-AC_RUN_IFELSE([#include "$srcdir/config/config.unexpected.m"],
-	have_unexpected=yes, have_unexpected=no, have_unexpected="$cross_have_unexpected")
+AC_RUN_IFELSE(
+  [AC_LANG_SOURCE([[#include "$srcdir/config/config.unexpected.m"]])],
+    have_unexpected=yes,
+    have_unexpected=no,
+    have_unexpected="$cross_have_unexpected")
 if test $have_unexpected = yes; then
   AC_DEFINE(HAVE_UNEXPECTED,1,
 	    [Define if libobjc has the _objc_unexpected_exception callback])
@@ -2106,7 +2121,8 @@ AC_SUBST(HAVE_OBJC_SYNC_ENTER)
 # Don't revert any Objective-C flags as they are used in the next test
 
 AC_MSG_CHECKING(for thread-safe +initialize in runtime)
-AC_RUN_IFELSE([#include "$srcdir/config/config.initialize.m"],
+AC_RUN_IFELSE(
+  [AC_LANG_SOURCE([[#include "$srcdir/config/config.initialize.m"]])],
 	safe_initialize=yes, safe_initialize=no, safe_initialize="$cross_safe_initialize")
 if test $safe_initialize = yes; then
   AC_DEFINE(HAVE_INITIALIZE,1,
@@ -2795,13 +2811,15 @@ have_forward_hook=yes
 saved_CPPFLAGS="$CPPFLAGS"
 CPPFLAGS="$CPPFLAGS $OBJCFLAGS -x objective-c"
 AC_MSG_CHECKING(for forwarding callback in runtime)
-AC_COMPILE_IFELSE([#include "$srcdir/config/config.forward2.m"],
+AC_COMPILE_IFELSE(
+  [AC_LANG_SOURCE([[#include "$srcdir/config/config.forward2.m"]])],
 	have_forward_hook=yes, have_forward_hook=no)
 if test $have_forward_hook = yes; then
   AC_DEFINE(HAVE_FORWARD2,1,
             [Define if libobjc has the __objc_msg_forward2 function])
 else
-  AC_COMPILE_IFELSE([#include "$srcdir/config/config.forward.m"],
+  AC_COMPILE_IFELSE(
+    [AC_LANG_SOURCE([[#include "$srcdir/config/config.forward.m"]])],
 	have_forward_hook=yes, have_forward_hook=no)
 fi
 AC_MSG_RESULT($have_forward_hook)
@@ -2850,7 +2868,8 @@ fi
 
 if test $enable_ffcall = yes -a $ffi_ok = yes; then
   AC_MSG_CHECKING(if ffcall trampolines work)
-  AC_RUN_IFELSE([#include "$srcdir/config/config.trampoline.c"],
+  AC_RUN_IFELSE(
+    [AC_LANG_SOURCE([[#include "$srcdir/config/config.trampoline.c"]])],
 	  have_working_trampoline=yes, have_working_trampoline=no, 
 	  have_working_trampoline=yes)
   AC_MSG_RESULT($have_working_trampoline)
@@ -2916,9 +2935,9 @@ AC_ARG_ENABLE(iconv,
 
 if test $enable_iconv = yes; then
 AC_MSG_CHECKING(iconv support)
-AC_RUN_IFELSE([[#include <iconv.h>
+AC_RUN_IFELSE([AC_LANG_SOURCE([#include <iconv.h>
 int main(int argc,char **argv)
-{ return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }]]
+{ return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }])]
 ,
   # libc has a working iconv.
   AC_DEFINE(HAVE_ICONV,1, [Define if you have this function])
@@ -2943,9 +2962,9 @@ if test $found_iconv = no ; then
 
   old_LIBS="$LIBS"
   LIBS="-liconv $LIBS"
-  AC_RUN_IFELSE([[#include <iconv.h>
+  AC_RUN_IFELSE([AC_LANG_SOURCE([#include <iconv.h>
   int main(int argc,char **argv)
-  { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }]]
+  { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }])]
   ,
     # -liconv works.
     AC_DEFINE(HAVE_ICONV,1, [Define if you have this function])
@@ -2967,9 +2986,9 @@ if test $found_iconv = no ; then
   # BSDs install this lib as libgiconv.
   old_LIBS="$LIBS"
   LIBS="-lgiconv $LIBS"
-  AC_RUN_IFELSE([[#include <giconv.h>
+  AC_RUN_IFELSE([AC_LANG_SOURCE([#include <giconv.h>
   int main(int argc,char **argv)
-  { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }]]
+  { return iconv_open("UTF-8//TRANSLIT","ASCII") == -1 ? 1 : 0; }])]
   ,
     AC_DEFINE(HAVE_ICONV,1, [Define if you have this function])
     AC_DEFINE(HAVE_GICONV,1, [Define if you have this function])
@@ -2991,9 +3010,9 @@ AC_ARG_ENABLE(stricticonv,
   enable_stricticonv=no)
 if test $enable_stricticonv = yes; then
 AC_MSG_CHECKING(non-lossy iconv support)
-AC_RUN_IFELSE([[#include <iconv.h>
+AC_RUN_IFELSE([AC_LANG_SOURCE([#include <iconv.h>
 int main(int argc,char **argv)
-{ return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }]]
+{ return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }])]
 ,
   # libc has a working iconv.
   AC_DEFINE(HAVE_ICONV,1, [Define if you have this function])
@@ -3016,9 +3035,9 @@ if test $found_iconv = no ; then
 
   old_LIBS="$LIBS"
   LIBS="-liconv $LIBS"
-  AC_RUN_IFELSE([[#include <iconv.h>
+  AC_RUN_IFELSE([AC_LANG_SOURCE([#include <iconv.h>
   int main(int argc,char **argv)
-  { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }]]
+  { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }])]
   ,
     # -liconv works.
     AC_DEFINE(HAVE_ICONV,1, [Define if you have this function])
@@ -3035,9 +3054,9 @@ if test $found_iconv = no ; then
   # BSDs install this lib as libgiconv.
   old_LIBS="$LIBS"
   LIBS="-lgiconv $LIBS"
-  AC_RUN_IFELSE([[#include <giconv.h>
+  AC_RUN_IFELSE([AC_LANG_SOURCE([#include <giconv.h>
   int main(int argc,char **argv)
-  { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }]]
+  { return iconv_open("UTF-8","ASCII") == -1 ? 1 : 0; }])]
   ,
     AC_DEFINE(HAVE_ICONV,1, [Define if you have this function])
     AC_DEFINE(HAVE_GICONV,1, [Define if you have this function])