rfc: build system

[Richard Henderson <rth at cygnus dot com>]

On Mon, Jan 31, 2000 at 09:08:56PM -0800, Zack Weinberg wrote:
> I had a much more complicated fix which got bogged down in the
> details.  I think this makefile is actually worse than glibc's
> Makerules, which is an achievement.

Speaking of which...  Being irritated with how poorly our build
system works with parallel make on SMP systems, I gave the make
system a half-hearted poke this weekend to see what level of
effort it would be to kill the (bulk of the) recursive makes.

I'm guessing that there are a number of folks that would be rather
pissed at gcc suddenly requiring gnu make.  My question is, what
sort of common denominator does that leave us with functionality-wise? 
And would folks be open to limitations in the make/configure process
to avoid things getting overly complex?

For instance, one can currently run configure with no args and do
"make LANGUAGES='c c++'".  The sanest way I can think to rework some
of the build rules is

    lang.fe: $(foreach lang,$(LANGUAGES),$(lang).fe)
or
    LIB2LANG_OBJS = $(foreach lang,$(LANGUAGES),$($(lang)_LIB2LANG_OBJS))

which clearly doesn't work without some sort of macro facility in make. 

Now, this same sort of thing could instead be expanded at Makefile
creation, at which point we aren't relying on gnu make features.  But
at the same time, we now require "configure --enable-languages='...'"
in order to change what builds.

Thoughts?


r~