Why is one compiler on 10.6 able to generate PPC binaries and not the other?

[Mojca Miklavec]

Hi,

While following
    https://trac.macports.org/wiki/LibcxxOnOlderSystems#Leopardppc
on 10.6/x86_64 I tried to install clang 3.7 (thinking that version 3.7
might have an even better support for PPC than 3.6).

The problem is that clang-mp-3.7 doesn't want to produce ppc binaries,
so I wasn't able to install libcxx. I get:

> clang++-mp-3.7 a.cc -arch ppc
ld: unknown/unsupported architecture name for: -arch ppc
clang: error: linker command failed with exit code 1 (use -v to see invocation)

At the same time clang++-mp-3.4 works fine even though both clang 3.4
and 3.7 are x86_64 only.

I'm now trying to rebuild everything as +universal (with ppc included
in the list of universal architectures) and hope that it will work
afterwards. But I would be grateful for ideas about why clang 3.4
would be able to create ppc binaries and clang 3.7 not.

Thank you,
   Mojca

PS: I'm not actually using the PPC, I'm doing this all for fun and as
a challenge. But I don't have any VM with 10.5, so I wanted to do the
cross-compiling step on VM with 10.6.