compile symbolic file in makefile

I just come across Makefile built in rule to compile symbolic file.

SRCS       =  a.c $(LINKED_SRCS)
endif

# ++ linked source
LINKED_SRCS= b.c

${LINKED_SRCS} links:  linkstamp

cleanlinks:
    @ - rm -f ${LINKED_SRCS} linkstamp

linkstamp:
    @ - rm -f ${LINKED_SRCS}
    ln -sf $(PROJECTDIR)/SRC/UsrLib_src/b.c b.c
    touch linkstamp



- This rule works, based on your linkstamp file, say if linkstamp file present - Makefile consider that symbolic link already presence.

-This rule will be executed before compiling b.c

-since b.c has links attached -- so b.c will not be compiled before link creation

step:1 -- compile a.c
step:2 -- create links
step 3: -- compile b.c

very interesting about links: