This example in the manual is talking about writing a custom
Makefile, *without* using Automake, that you want to recurse
into using Automake's SUBDIRS feature.
Aha! Thanks for pointing this out. I think the manual is misleading in another place, because I got to this section via this cross-reference:
To make ‘dvi’ into a do-nothing target, see the example for
‘EMPTY_AUTOMAKE_TARGETS’ in *note Third-Party Makefiles::.
This is in the section "dvi and distcheck", which AFAICT is about Makefile.am, not third-party Makefiles.
> If I instead have:
> then it is not.
This is right way to override the dvi target that would
otherwise be generated by Automake.
So it seems that this is what the section "dvi and distcheck" should advise.