Use a target-specific variable to add to CPPFLAGS instead of writing a
custom .c -> .o rule. This will ensure that dependency tracking is
used when enabled.
# dependencies ensure that path changes propagate
pg_regress.o: pg_regress.c $(top_builddir)/src/port/pg_config_paths.h
- $(CC) $(CFLAGS) $(CPPFLAGS) -I$(top_builddir)/src/port $(EXTRADEFS) -c -o $@ $<
+pg_regress.o: override CPPFLAGS += -I$(top_builddir)/src/port $(EXTRADEFS)
$(top_builddir)/src/port/pg_config_paths.h: $(top_builddir)/src/Makefile.global
$(MAKE) -C $(top_builddir)/src/port pg_config_paths.h