Build fails through dependency with clang-7.0 [10.5/PPC]

[xanda-escuyer (xanda)]

We experience build failure because of dependancy lower down the food chain:-

Error: clang-7.0 cannot be installed for the configured build_arch 'ppc' because it only supports the arch(s) 'i386 x86_64'.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port clang-7.0 failed

Yet looking at the official build report it does not seem that this should be a factor:- ​https://build.macports.org/builders/ports-10.5_ppc_legacy-builder/builds/92712

Please would you help us with any insight so we can find a solution. Thanks.

[kencu (Ken)]

That error is (currently) telling you the truth, and there is no defect in the error message. The MacPorts clang-7.0 port cannot be installed for ppc because it only supports i386/x86_64 (at this time).

I have been working on making some useful version of clang available for 32bit Darwin PowerPC for some time, and the (very skilled) GCC Darwin lead has as well, in a much more skilled fashion than I have been, but it is not as yet working. Mainly, this is due to the fact that the Darwin PowerPC ABI was never finished in LLVM, and currently does not output ABI-appropriate structures.

You can play with what does work, however. If you have skills and interest, if you can fix the Darwin PowerPC ABI that would be helpful. See this github repo <​https://github.com/iains/LLVM-7-branch> for the current state of affairs.

If you don't mind, I will close this ticket here on MacPorts, as there is nothing to fix here. If and when clang-7.0 does become available for PowerPC, I will certainly update the clang-7.0 Portfile to support it here on MacPorts.

Glad to have you on board with the fixes, if you can help!

[kencu (Ken)]

Now -- there could be an error in that MacPorts is sending you to a known-failing compiler when you try to install some piece of software. There are lots of holes in MacPorts' compiler selection when it comes to PPC I'm afraid, and this happens fairly often. If you tell me which piece of software led to PPC trying to install clang-7.0, we might be able to get that error fixed.

[xanda-escuyer (xanda)]

If you tell me which piece of software led to PPC trying to install clang-7.0...

This is the part we need some help with.

If it's relevant, this error first arose a while back on a previous transcode release (sorry but so long ago that we're unable to be more specific).

After seeing from the official build log that it ought to work, we tried once again but get stuck on this same hurdle.

Have you any thoughts on how we determine the reason for clang-7.0 being pulled in? Thank you.

[kencu (Ken)]

is it transcode you are hoping to install on PPC? Let me see what happens with that when I try it...

[ryandesign (Ryan Carsten Schmidt)]

Replying to xanda-escuyer:

Yet looking at the official build report it does not seem that this should be a factor:- ​https://build.macports.org/builders/ports-10.5_ppc_legacy-builder/builds/92712

"Official build repots" for 10.5 ppc are unlikely to be of any use at this point, since they are all ancient; the Power Mac that did the 10.5 ppc builds has been offline for a year or more.

[xanda-escuyer (xanda)]

We have managed to succeed in building transcode.

The build came good after running port uninstall leaves which presumably cleared the necessary clang-7.0 issue.