Check for -Wno-unused-but-set-variable gcc support

Gcc versions 4.3.2 and earlier do not support the compiler flag
-Wno-unused-but-set-variable.  This can lead to build failures
on older Linux platforms such as Debian Lenny.  Since this is
an optional build argument this changes add a new autoconf check
for the option.  If it is supported by the installed version of
gcc then it is used otherwise it is omited.

See commit's 12c1acde76683108441827ae9affba1872f3afe5 and
79713039a2b6e0ed223d141b4a8a8455f282d2f2 for the reason the
-Wno-unused-but-set-variable options was originally added.

20 files changed, 49 insertions, 9 deletions

diff --git a/lib/Makefile.in b/lib/Makefile.in
index 9b8072571..2524789fe 100644
--- a/lib/Makefile.in
+++ b/lib/Makefile.in
@@ -70,6 +70,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -201,6 +202,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libavl/Makefile.in b/lib/libavl/Makefile.in
index eef898b38..25c258837 100644
--- a/lib/libavl/Makefile.in
+++ b/lib/libavl/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -213,6 +214,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -312,7 +314,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \
diff --git a/lib/libefi/Makefile.in b/lib/libefi/Makefile.in
index 3f712bc62..d5635d6a6 100644
--- a/lib/libefi/Makefile.in
+++ b/lib/libefi/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -213,6 +214,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -312,7 +314,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \
diff --git a/lib/libnvpair/Makefile.in b/lib/libnvpair/Makefile.in
index 51fafc98b..277225c88 100644
--- a/lib/libnvpair/Makefile.in
+++ b/lib/libnvpair/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -214,6 +215,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -313,7 +315,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \
diff --git a/lib/libspl/Makefile.in b/lib/libspl/Makefile.in
index 631638962..4c9767d0b 100644
--- a/lib/libspl/Makefile.in
+++ b/lib/libspl/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -264,6 +265,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -363,7 +365,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \
diff --git a/lib/libspl/asm-generic/Makefile.in b/lib/libspl/asm-generic/Makefile.in
index 60f5f4b48..1de95138a 100644
--- a/lib/libspl/asm-generic/Makefile.in
+++ b/lib/libspl/asm-generic/Makefile.in
@@ -71,6 +71,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -162,6 +163,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -261,7 +263,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\"
diff --git a/lib/libspl/asm-i386/Makefile.in b/lib/libspl/asm-i386/Makefile.in
index c063f0910..60f83d44a 100644
--- a/lib/libspl/asm-i386/Makefile.in
+++ b/lib/libspl/asm-i386/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -166,6 +167,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/asm-x86_64/Makefile.in b/lib/libspl/asm-x86_64/Makefile.in
index e6cb98290..223bbd791 100644
--- a/lib/libspl/asm-x86_64/Makefile.in
+++ b/lib/libspl/asm-x86_64/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -166,6 +167,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/Makefile.in b/lib/libspl/include/Makefile.in
index 1f3c99b91..04892246c 100644
--- a/lib/libspl/include/Makefile.in
+++ b/lib/libspl/include/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -226,6 +227,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/ia32/Makefile.in b/lib/libspl/include/ia32/Makefile.in
index c46466150..08b86be00 100644
--- a/lib/libspl/include/ia32/Makefile.in
+++ b/lib/libspl/include/ia32/Makefile.in
@@ -70,6 +70,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -201,6 +202,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/ia32/sys/Makefile.in b/lib/libspl/include/ia32/sys/Makefile.in
index c8ec864f8..58a7d89d3 100644
--- a/lib/libspl/include/ia32/sys/Makefile.in
+++ b/lib/libspl/include/ia32/sys/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -188,6 +189,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/rpc/Makefile.in b/lib/libspl/include/rpc/Makefile.in
index 9ceb73f50..437898264 100644
--- a/lib/libspl/include/rpc/Makefile.in
+++ b/lib/libspl/include/rpc/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -188,6 +189,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/sys/Makefile.in b/lib/libspl/include/sys/Makefile.in
index a65b9374e..eff3720c8 100644
--- a/lib/libspl/include/sys/Makefile.in
+++ b/lib/libspl/include/sys/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -226,6 +227,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/sys/dktp/Makefile.in b/lib/libspl/include/sys/dktp/Makefile.in
index c90dbff5b..ceab063ab 100644
--- a/lib/libspl/include/sys/dktp/Makefile.in
+++ b/lib/libspl/include/sys/dktp/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -188,6 +189,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/sys/sysevent/Makefile.in b/lib/libspl/include/sys/sysevent/Makefile.in
index e176934ad..10e7c1fbb 100644
--- a/lib/libspl/include/sys/sysevent/Makefile.in
+++ b/lib/libspl/include/sys/sysevent/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -188,6 +189,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libspl/include/util/Makefile.in b/lib/libspl/include/util/Makefile.in
index 16db23b47..274d90c80 100644
--- a/lib/libspl/include/util/Makefile.in
+++ b/lib/libspl/include/util/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -188,6 +189,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
diff --git a/lib/libunicode/Makefile.in b/lib/libunicode/Makefile.in
index a8c054da1..95606731e 100644
--- a/lib/libunicode/Makefile.in
+++ b/lib/libunicode/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -213,6 +214,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -312,7 +314,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \
diff --git a/lib/libuutil/Makefile.in b/lib/libuutil/Makefile.in
index 0fbfdff95..304a2685b 100644
--- a/lib/libuutil/Makefile.in
+++ b/lib/libuutil/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -215,6 +216,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -314,7 +316,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \
diff --git a/lib/libzfs/Makefile.in b/lib/libzfs/Makefile.in
index 245a77eb7..aad4c8cd7 100644
--- a/lib/libzfs/Makefile.in
+++ b/lib/libzfs/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -223,6 +224,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -322,7 +324,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\"
diff --git a/lib/libzpool/Makefile.in b/lib/libzpool/Makefile.in
index be18e0b17..7c2b37235 100644
--- a/lib/libzpool/Makefile.in
+++ b/lib/libzpool/Makefile.in
@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/user-ioctl.m4 \
 	$(top_srcdir)/config/user-libblkid.m4 \
 	$(top_srcdir)/config/user-libuuid.m4 \
+	$(top_srcdir)/config/user-no-unused-but-set-variable.m4 \
 	$(top_srcdir)/config/user-nptl_guard_within_stack.m4 \
 	$(top_srcdir)/config/user-selinux.m4 \
 	$(top_srcdir)/config/user-zlib.m4 $(top_srcdir)/config/user.m4 \
@@ -234,6 +235,7 @@ MAKEINFO = @MAKEINFO@
 MKDIR_P = @MKDIR_P@
 NM = @NM@
 NMEDIT = @NMEDIT@
+NO_UNUSED_BUT_SET_VARIABLE = @NO_UNUSED_BUT_SET_VARIABLE@
 OBJDUMP = @OBJDUMP@
 OBJEXT = @OBJEXT@
 OTOOL = @OTOOL@
@@ -333,7 +335,7 @@ DEFAULT_INCLUDES = -include ${top_builddir}/zfs_config.h \
 	-I$(top_srcdir)/include -I$(top_srcdir)/lib/libspl/include
 AM_LIBTOOLFLAGS = --silent
 AM_CFLAGS = -Wall -Wstrict-prototypes -fno-strict-aliasing \
-	-Wno-unused-but-set-variable ${DEBUG_CFLAGS} -D_GNU_SOURCE \
+	${NO_UNUSED_BUT_SET_VARIABLE} ${DEBUG_CFLAGS} -D_GNU_SOURCE \
 	-D__EXTENSIONS__ -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS \
 	-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE \
 	-DTEXT_DOMAIN=\"zfs-linux-user\" $(DEBUG_STACKFLAGS) \