+subdirmk: warning: ./Dir.sd.mk:8: possibly confusing unbracketed single-char $-expansion
+subdirmk: warning: saw both WARN and &WARN
+ saw WARN at ./Dir.sd.mk:6
+ saw WARN at ./Dir.sd.mk:9
+ saw &WARN at ./Dir.sd.mk:7
+ saw &WARN at ./Dir.sd.mk:10
+ saw &WARN at ./Dir.sd.mk:11