how does cross-compilation actually work in meson?

[stsp]

Hi guys.

I've read the meson's cross-compilation doc
very carefully and more than once, and I have
to say it doesn't explain a tiny bit. I'll try to
formulate questions, but I don't have a basic
understanding, so even that is challenging. :)

So I have a cross file with c = 'clang',
whereas the doc has c = 'x86_64-w64-mingw32-gcc'
as an example. While its quite clear what
happens with the documented mingw
example, clang needs passing the
-target option to cross-compile
(-target means host in meson't notation).
And meson doesn't seem to pass this...
Does meson think that whatever I
put into a cross file, can be invoked
as-is, like is the case with mingw?

Speaking of "host", again, the doc
doesn't say how exactly meson evaluates
the host triplet. It just basically suggests
to hard-code some values and access
them from meson.build... Nice, but this
is what I am doing with plain makefiles
w/o any problems. I thought meson can
look up the host triplet for me by analysing
the host description in a toolchain file,
AND by looking up what binutils are
available for suitable cross-prefixes.
For example, I describe host as this:

[host_machine]
system = 'linux'
cpu_family = 'x86'
cpu = 'i386'
endian = 'little'

But there are huge variety of cross-prefixes
that can suit that: i686-linux-gnu, i386-linux-gnu,
x86_64-linux-gnu (in that case as will need --32
and ld will need specific -m for 32bits) and so on.
So I though meson can look up the suitable
binutils, and pass the appropriate -target
to clang (I am using c_ld = 'bfd' which is
why I supposed it would look for binutils),
but it doesn't do anything of that kind and
I don't see anything in the doc saying how
to ask him to do that.

Now, my project uses nasm, but, because
I also use cpp (c preprocessor), I had to
write ['nasm', 'c'] in the project description.
It seems otherwise I can't use preprocessor.
And this seems to be enough for meson to
use C compiler (clang in my case) for linking!
I suppose if the project would mention only
nasm, then meson would use the linker
directly, but since I need preprocessor,
meson uses clang... How can I tell him to
not use C compiler for linking, as my project
only uses cpp? Of course if I find the way
to tell meson to not use clang for linking,
then immediately I'll need to stop him from
using plain ld.bfd and find the suitable
cross-binutils...

Sorry for such a long posting.
Cross-compilation is a difficult subject,
but the existing doc makes it even more
difficult by explaining nothing but discussing
what is build-host-target in a great lengths...
But people know what is build-host-target.
People (me :) don't know how to use meson
for cross-compiling.