Fix unused variable warning

The local mg variable is unused in non-debug builds.
Wrap the variable in ASSERTV() so that it's only present
in the debug build.  Introduced by OpenZFS 7303.

Reviewed-by: Don Brady <don.brady@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #5616

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 7f5de16aa246074250489beb7c5b763ea9a2caa9..f7d3dbb8bba4e5df62e094fcf176ce45ce8592a5 100644 (file)
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -2654,7 +2654,7 @@ zdb_leak_init(spa_t *spa, zdb_cb_t *zcb)
 
                for (c = 0; c < rvd->vdev_children; c++) {
                        vdev_t *vd = rvd->vdev_child[c];
-                       metaslab_group_t *mg = vd->vdev_mg;
+                       ASSERTV(metaslab_group_t *mg = vd->vdev_mg);
                        for (m = 0; m < vd->vdev_ms_count; m++) {
                                metaslab_t *msp = vd->vdev_ms[m];
                                ASSERT3P(msp->ms_group, ==, mg);
@@ -2713,7 +2713,7 @@ zdb_leak_fini(spa_t *spa)
                vdev_t *rvd = spa->spa_root_vdev;
                for (c = 0; c < rvd->vdev_children; c++) {
                        vdev_t *vd = rvd->vdev_child[c];
-                       metaslab_group_t *mg = vd->vdev_mg;
+                       ASSERTV(metaslab_group_t *mg = vd->vdev_mg);
                        for (m = 0; m < vd->vdev_ms_count; m++) {
                                metaslab_t *msp = vd->vdev_ms[m];
                                ASSERT3P(mg, ==, msp->ms_group);