double-colon AND phony rules

[Adam Kellas]

Is there anything particularly wrong with making rules double-colon as
long as they're phony also? The manual doesn't address this exact
combination though it's quite frowny about double-colon rules overall
(the general tone is "don't use them unless you really know what
you're doing, and if you really knew what you were doing you wouldn't
use them"). I can see the general arguments against them but not when
they're phony as well.

Background: I'm cleaning up an old build system and have a  makefile
which should be usable either directly (by typing "make" in its
directory, for backward compatibility) or as an include file (new
style). It's a tiny little thing, basically:

.PHONY: all clean

all:
       [create a couple of files]

clean:
       [remove target files]

But in this form "all" and "clean" will break when included. Any
reason not to use "all::" and "clean::" throughout the build system?

Thanks,
AK