+subdirmk: warning (broken-var-ref): ./Dir.sd.mk:19: broken $&... expansion; you probably meant &$
+subdirmk: warning (local+global): saw both NOWARN1 and &NOWARN1
+ saw NOWARN1 at ./sub/dir/Dir.sd.mk:24
+ saw &NOWARN1 at ./Dir.sd.mk:14
+ expectedly saw NOWARN1 at ./Dir.sd.mk:14