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Date:      Wed, 14 Oct 2015 22:05:10 -0700
From:      Bryan Drewery <bdrewery@FreeBSD.org>
To:        arch@FreeBSD.org
Subject:   make -n -n
Message-ID:  <561F3406.9050906@FreeBSD.org>

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Does anyone consider 'make -n -n' a thing for top-level builds?

We have this ${_+_} thing in Makefiles that used to expand to '+' if you
gave '-n -n'.  This was so just 1 '-n' would just show what the
top-level Makefile would do:

~/svn/clean2 # make -n includes
cd /root/svn/clean2; PATH=3D/sbin:/bin:/usr/sbin:/usr/bin make -m
/root/svn/clean2/share/mk -f Makefile.inc1 TARGET=3Damd64
TARGET_ARCH=3Damd64 includes

Versus the more expected (at least for bmake) -n behavior of traversing
sub-makes:

~/svn/clean2 # make -n -n includes
=3D=3D=3D> lib (includes)
=3D=3D=3D> lib/csu (includes)
=3D=3D=3D> lib/csu/amd64 (includes)
=3D=3D=3D> lib/libcompiler_rt (includes)
=3D=3D=3D> lib/libc (includes)
=3D=3D=3D> lib/libc/tests (includes)
=3D=3D=3D> lib/libc/tests/tls_dso (includes)
=3D=3D=3D> lib/libc/tests/c063 (includes)
etc...

Note the actual output may be off due to local changes, but the point is
that -n with bmake is documented to run sub-makes with -n as well, so it
calls right down the chain showing all build commands without taking any
real actions.

Bmake added a '-N' flag that essentially does the hack that we've put
into our top-level Makefile - it doesn't run sub-makes.


So having said all of that, the ${_+_} never expands anymore since
r251748 (June 2013). The act of it working in top-level has only been
fixed since r288391 (September 2015).

Given it was broken for this long period I assume no one uses '-n -n' or
even knew about it.

I would like to remove it (-n -n and _+_) and just use the (bmake)
documented -n and -N flags and use '+' everywhere appropriate. Note that
we use .MAKE in some targets that achieves largely the same thing, but
many sub-make calls don't have a .MAKE and lack a proper '+' to recurse
in Makefile.inc1.

--=20
Regards,
Bryan Drewery



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