Fix configure tests to play nice with GCC 4.6

As of GCC 4.6, specific kernel 2.6.32 header files do not compile
cleanly without warnings. One specific example of this is the
arch/x86/include/asm/percpu.h file. Thus, a few of the configure tests
were getting hung up on this and the '-Wno-unsued-but-set-variables'
compile option had to be introduced.

Signed-off-by: Prakash Surya <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #459

12 files changed, 99 insertions, 0 deletions

diff --git a/config/kernel-bdev-block-device-operations.m4 b/config/kernel-bdev-block-device-operations.m4
index daf14f0f9..2805237aa 100644
--- a/config/kernel-bdev-block-device-operations.m4
+++ b/config/kernel-bdev-block-device-operations.m4
@@ -3,6 +3,8 @@ dnl # 2.6.x API change
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS], [
 	AC_MSG_CHECKING([block device operation prototypes])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -30,4 +32,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS], [
 	],[
 		AC_MSG_RESULT(struct inode)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-bdev-logical-size.m4 b/config/kernel-bdev-logical-size.m4
index 1e199663b..d066c863f 100644
--- a/config/kernel-bdev-logical-size.m4
+++ b/config/kernel-bdev-logical-size.m4
@@ -7,6 +7,8 @@ dnl # it explicit.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BDEV_LOGICAL_BLOCK_SIZE], [
 	AC_MSG_CHECKING([whether bdev_logical_block_size() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -19,4 +21,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BDEV_LOGICAL_BLOCK_SIZE], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-blk-end-request.m4 b/config/kernel-blk-end-request.m4
index 20ad1a926..0228fb0f9 100644
--- a/config/kernel-blk-end-request.m4
+++ b/config/kernel-blk-end-request.m4
@@ -5,6 +5,8 @@ dnl # changed in 2.6.31 so it may be used by non-GPL modules.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BLK_END_REQUEST], [
 	AC_MSG_CHECKING([whether blk_end_request() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -34,4 +36,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_END_REQUEST], [
 		AC_DEFINE(HAVE_BLK_END_REQUEST_GPL_ONLY, 1,
 		          [blk_end_request() is GPL-only])
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-blk-fetch-request.m4 b/config/kernel-blk-fetch-request.m4
index 34a5d2fa8..c277f52c0 100644
--- a/config/kernel-blk-fetch-request.m4
+++ b/config/kernel-blk-fetch-request.m4
@@ -7,6 +7,8 @@ dnl # next available request and removed it from the request queue.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BLK_FETCH_REQUEST], [
 	AC_MSG_CHECKING([whether blk_fetch_request() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -19,4 +21,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_FETCH_REQUEST], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-blk-requeue-request.m4 b/config/kernel-blk-requeue-request.m4
index f676f85cb..d8e7439e0 100644
--- a/config/kernel-blk-requeue-request.m4
+++ b/config/kernel-blk-requeue-request.m4
@@ -6,6 +6,8 @@ dnl # blk_requeue_request() function.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BLK_REQUEUE_REQUEST], [
 	AC_MSG_CHECKING([whether blk_requeue_request() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -19,4 +21,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_REQUEUE_REQUEST], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-blk-rq-bytes.m4 b/config/kernel-blk-rq-bytes.m4
index da83405cb..6430dfe50 100644
--- a/config/kernel-blk-rq-bytes.m4
+++ b/config/kernel-blk-rq-bytes.m4
@@ -6,6 +6,8 @@ dnl blk_rq_bytes() helper was changed to a static inline which we can use.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BLK_RQ_BYTES], [
 	AC_MSG_CHECKING([whether blk_rq_bytes() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -35,4 +37,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_RQ_BYTES], [
 		AC_DEFINE(HAVE_BLK_RQ_BYTES_GPL_ONLY, 1,
 		          [blk_rq_bytes() is GPL-only])
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-blk-rq-pos.m4 b/config/kernel-blk-rq-pos.m4
index aaa464665..fd8a92657 100644
--- a/config/kernel-blk-rq-pos.m4
+++ b/config/kernel-blk-rq-pos.m4
@@ -3,6 +3,8 @@ dnl # 2.6.31 API change
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BLK_RQ_POS], [
 	AC_MSG_CHECKING([whether blk_rq_pos() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -15,4 +17,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_RQ_POS], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-blk-rq-sectors.m4 b/config/kernel-blk-rq-sectors.m4
index db8c43938..fbcd11320 100644
--- a/config/kernel-blk-rq-sectors.m4
+++ b/config/kernel-blk-rq-sectors.m4
@@ -3,6 +3,8 @@ dnl # 2.6.31 API change
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BLK_RQ_SECTORS], [
 	AC_MSG_CHECKING([whether blk_rq_sectors() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -15,4 +17,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_RQ_SECTORS], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-get-disk-ro.m4 b/config/kernel-get-disk-ro.m4
index 365afdbc6..aac69b7a1 100644
--- a/config/kernel-get-disk-ro.m4
+++ b/config/kernel-get-disk-ro.m4
@@ -3,6 +3,8 @@ dnl # 2.6.x API change
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_GET_DISK_RO], [
 	AC_MSG_CHECKING([whether get_disk_ro() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -15,4 +17,5 @@ AC_DEFUN([ZFS_AC_KERNEL_GET_DISK_RO], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-rq-for-each_segment.m4 b/config/kernel-rq-for-each_segment.m4
index 15f030f35..182147817 100644
--- a/config/kernel-rq-for-each_segment.m4
+++ b/config/kernel-rq-for-each_segment.m4
@@ -3,6 +3,8 @@ dnl # 2.6.x API change
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_RQ_FOR_EACH_SEGMENT], [
 	AC_MSG_CHECKING([whether rq_for_each_segment() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -17,4 +19,5 @@ AC_DEFUN([ZFS_AC_KERNEL_RQ_FOR_EACH_SEGMENT], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/config/kernel-rq-is_sync.m4 b/config/kernel-rq-is_sync.m4
index 40d0de80c..507bf683e 100644
--- a/config/kernel-rq-is_sync.m4
+++ b/config/kernel-rq-is_sync.m4
@@ -3,6 +3,8 @@ dnl # 2.6.x API change
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_RQ_IS_SYNC], [
 	AC_MSG_CHECKING([whether rq_is_sync() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
 	],[
@@ -15,4 +17,5 @@ AC_DEFUN([ZFS_AC_KERNEL_RQ_IS_SYNC], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
diff --git a/configure b/configure
index 89596d98e..885d5eb09 100755
--- a/configure
+++ b/configure
@@ -12486,6 +12486,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking block device operation prototypes" >&5
 $as_echo_n "checking block device operation prototypes... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -12563,6 +12565,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 	{ $as_echo "$as_me:$LINENO: checking whether kernel defines fmode_t" >&5
 $as_echo_n "checking whether kernel defines fmode_t... " >&6; }
@@ -12869,6 +12872,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking whether bdev_logical_block_size() is available" >&5
 $as_echo_n "checking whether bdev_logical_block_size() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -12931,6 +12936,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether bio_empty_barrier() is defined" >&5
@@ -13471,6 +13477,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_end_request() is available" >&5
 $as_echo_n "checking whether blk_end_request() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -13601,10 +13609,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_fetch_request() is available" >&5
 $as_echo_n "checking whether blk_fetch_request() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -13667,10 +13678,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_requeue_request() is available" >&5
 $as_echo_n "checking whether blk_requeue_request() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -13734,10 +13748,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_rq_bytes() is available" >&5
 $as_echo_n "checking whether blk_rq_bytes() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -13868,10 +13885,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_rq_pos() is available" >&5
 $as_echo_n "checking whether blk_rq_pos() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -13934,10 +13954,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_rq_sectors() is available" >&5
 $as_echo_n "checking whether blk_rq_sectors() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -14000,10 +14023,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether get_disk_ro() is available" >&5
 $as_echo_n "checking whether get_disk_ro() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -14066,10 +14092,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether rq_is_sync() is available" >&5
 $as_echo_n "checking whether rq_is_sync() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -14132,10 +14161,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether rq_for_each_segment() is available" >&5
 $as_echo_n "checking whether rq_for_each_segment() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -14200,6 +14232,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 	{ $as_echo "$as_me:$LINENO: checking whether super_block uses const struct xattr_hander" >&5
 $as_echo_n "checking whether super_block uses const struct xattr_hander... " >&6; }
@@ -17223,6 +17256,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking block device operation prototypes" >&5
 $as_echo_n "checking block device operation prototypes... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -17300,6 +17335,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 	{ $as_echo "$as_me:$LINENO: checking whether kernel defines fmode_t" >&5
 $as_echo_n "checking whether kernel defines fmode_t... " >&6; }
@@ -17606,6 +17642,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking whether bdev_logical_block_size() is available" >&5
 $as_echo_n "checking whether bdev_logical_block_size() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -17668,6 +17706,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether bio_empty_barrier() is defined" >&5
@@ -18208,6 +18247,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_end_request() is available" >&5
 $as_echo_n "checking whether blk_end_request() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18338,10 +18379,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_fetch_request() is available" >&5
 $as_echo_n "checking whether blk_fetch_request() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18404,10 +18448,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_requeue_request() is available" >&5
 $as_echo_n "checking whether blk_requeue_request() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18471,10 +18518,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_rq_bytes() is available" >&5
 $as_echo_n "checking whether blk_rq_bytes() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18605,10 +18655,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_rq_pos() is available" >&5
 $as_echo_n "checking whether blk_rq_pos() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18671,10 +18724,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether blk_rq_sectors() is available" >&5
 $as_echo_n "checking whether blk_rq_sectors() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18737,10 +18793,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether get_disk_ro() is available" >&5
 $as_echo_n "checking whether get_disk_ro() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18803,10 +18862,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether rq_is_sync() is available" >&5
 $as_echo_n "checking whether rq_is_sync() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18869,10 +18931,13 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether rq_for_each_segment() is available" >&5
 $as_echo_n "checking whether rq_for_each_segment() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -18937,6 +19002,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 	{ $as_echo "$as_me:$LINENO: checking whether super_block uses const struct xattr_hander" >&5
 $as_echo_n "checking whether super_block uses const struct xattr_hander... " >&6; }