Re: make -V

[Alan Barrett <apb%cequrux.com@localhost>]

On Wed, 22 Aug 2012, Simon J. Gerraty wrote:
> On Sun, 12 Aug 2012 05:14:36 +1000, matthew green writes:
> > > No problem.  It would seem the consensus is leave things as is.
> > > It would have been useful to not have to re-work all the freebsd ports
> > > collection - which relies on make -V PKGNAME doing full expansion.
>
> What if this behavior were controlled by a knob
> such that the default behavior is unchanged?
>
> This would allow a setting in sys.mk for FreeBSD to maintain
> compatability for them.

How about attacking the problem from a different direction?

The basic issue, I think, is that we want a way, from the command 
line, to print both the recursively-expanded value of a named 
variable, and the expanded-only-once value of a named variable. 
Which of the two behaviours is invoked by "make -V" is less 
important than the availability of both behaviours.

At present, in NetBSD, we can use:

        make -V VARNAME         # expanded only once
        make -V '${VARNAME}'    # expanded recursively

and in FreeBSD they have:

        make -V VARNAME         # expanded recursively
        # is there a way to expand only once?

My suggestion is to add a :modifier, such as :1, :e1, :x1, or even 
:texpandonce, to request that a variable be expanded only once.

Then we would be able to use:

        make -V '${VARNAME:e1}' # expanded only once
        make -V '${VARNAME}'    # expanded recursively
        make -V VARNAME         # to be decided

Now, moving on to which behaviour should be invoked by "make -V":

I couldn't find anything in the NetBSD src or pkgsrc tree 
that relies on "make -V VARNAME" expanding only once.  In 
fact, the uses of "make -V" that I found all seem to want the 
recursively-expanded value, and they probably work only by chance 
because the values don't happen to require expansion more than 
once.  We have also heard that FreeBSD's ports tree assumes that 
"make -V" expands recursively.  So, I suggest that we should 
change "make -V" to expand recursively.

--apb (Alan Barrett)