Re: how well does multi-arch build handle recursive building?

[Greg Chicares]

On 2006-5-11 18:23 UTC, Robert P. J. Day wrote:
>   at the moment, i'm using paul's multi-architecture build described
> here:
> 
> http://make.paulandlesley.org/multi-arch.html
> 
> successfully for simple builds for which all of the source files are
> in a single directory.  (i'm not actually doing multi-architecture
> builds, i'm just using that technique to build the results in a remote
> directory.  same difference, obviously.)

I use that technique in day-to-day production, for multiple
compilers, placing object and other binary files in compiler-
specific directories. Source files are scattered here and
there, but vpath means I don't need to worry about that.

> so how well does that technique extend to recursive builds?

It applies a single makefile recursively over directories.

>  does it
> *naturally* handle a recursive set of makefiles, or do i have to add
> that extra makefile wrapper at every level of the recursive build
> directory hierarchy?

What sort of problem are your existing recursive makefiles
designed to solve? What problem do they not solve that adding
this technique would solve? The 'multi-arch" paper's technique
already recursively invokes make; why mix it in with another
presumably different sort of recursion?

> i realize i could probably figure that out just from examining the
> code but i'm already being pushed intellectually just to keep a handle
> on the simpler case.

The implementation details may look daunting at first, but once
you understand them, the essential concept is really simple:
$(MAKE) -C in a distinct build directory, letting vpath figure
out where to find the source files. I found it easier to learn,
personally, by copying the "macro" files into a main makefile
instead of including them.