I'm in the process of developing a Portfile for my application and I'm running into problems during the destroot phase. According to the MacPorts guide, the destroot phase executes the following command:

make install DESTDIR=${destroot}

I think I may be misunderstanding how this is supposed to work in the Makefile. My application is very simple and the install rule only needs to copy a couple of directories to the DESTDIR so it is specified as follows:

install:
    cp -R bin $(DESTDIR)/bin
    cp -R lib $(DESTDIR)/lib
    cp -R cfg $(DESTDIR)/cfg

However, when I try to do a MacPort installation of my application, I get the following warnings:

--->  Staging test into destroot
Warning: violation by /bin
Warning: violation by /lib
Warning: violation by /cfg
Warning: test violates the layout of the ports-filesystems!

How do I fix this? Am I misunderstanding how the DESTDIR variable is used in the install rule or missing something altogether?