+# Add intermediate targets:
+# When building objects with specific suffix patterns, add intermediate
+# targets that the final targets are derived from.
+intermediate_targets = $(foreach sfx, $(2), \
+ $(patsubst %$(strip $(1)),%$(sfx), \
+ $(filter %$(strip $(1)), $(targets))))
+# %.lex.o <- %.lex.c <- %.l
+# %.tab.o <- %.tab.[ch] <- %.y
+targets += $(call intermediate_targets, .lex.o, .lex.c) \
+ $(call intermediate_targets, .tab.o, .tab.c .tab.h)
+