From 71144e676e710b37966f447ccd8d944813dfa6d1 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 11 Feb 2019 13:30:52 -0700
Subject: [PATCH] configure: enable -Wimplicit-fallthrough if we have it

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 configure | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/configure b/configure
index c4fffd99..6e549cdc 100755
--- a/configure
+++ b/configure
@@ -2312,6 +2312,20 @@ if compile_prog "" "" "__kernel_rwf_t"; then
 fi
 print_config "__kernel_rwf_t" "$__kernel_rwf_t"
 
+##########################################
+# check if gcc has -Wimplicit-fallthrough
+fallthrough="no"
+cat > $TMPC << EOF
+int main(int argc, char **argv)
+{
+  return 0;
+}
+EOF
+if compile_prog "-Wimplicit-fallthrough" "" "-Wimplicit-fallthrough"; then
+  fallthrough="yes"
+fi
+print_config "-Wimplicit-fallthrough" "$fallthrough"
+
 #############################################################################
 
 if test "$wordsize" = "64" ; then
@@ -2583,6 +2597,9 @@ fi
 if test "$__kernel_rwf_t" = "yes"; then
   output_sym "CONFIG_HAVE_KERNEL_RWF_T"
 fi
+if test "$fallthrough" = "yes"; then
+  CFLAGS="$CFLAGS -Wimplicit-fallthrough"
+fi
 
 echo "LIBS+=$LIBS" >> $config_host_mak
 echo "GFIO_LIBS+=$GFIO_LIBS" >> $config_host_mak
-- 
2.25.1