-include is not completely silent?

[Mohun Biswas]

I'd hesitate to call this a bug, as it's not actually inconsistent with the 
documentation, but it was a little surprising to me and I'm curious whether 
it's deliberate and/or well-known. The -include directive is documented as 
"acts like include in every way except that there is no error (not even a 
warning) if any of the filenames do not exist". But if the list of 
filenames is actually empty you still get a warning. This is a subtlety 
that wouldn't occur too often, because by standard shell behavior even if 
you say

-include *.P

and no files match the pattern, a literal "*.P" would be returned 
(presumably) and make would still be silent. But I just tried the following 
to pick up a few dependencies from a subdirectory:

-include $(shell find . -name \*.P -print)

and get the warning:

Makefile:282: no file name for `-include'

in the case where no .P files exist yet. IMHO, silent should mean silent 
but there may be history I don't know about here.

I remember some Unix variant used to behave like this with "rm -f" so you'd 
have to say something like "rm -f $(FILES) /dev/null" to make sure rm saw 
at least one file and didn't complain. I believe that was eventually "fixed".

Thanks,
MB