"Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option" [What's the meaning of this output line?]

[Ryan Schmidt]

On Aug 12, 2015, at 8:09 PM, Kurt Pfeifle wrote:

> When trying to install some ports on a newly upgraded Yosemite system, I get these lines:
> 
> Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
> 
> For example, it happens for the sam2p port. Here this line is repeated about two dozen times even:
> 
> --->  Configuring sam2p
> Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option

This means that the sam2p port declares that it is not compatible with some compilers: in fact, it declares that it is not compatible with every compiler that is compatible with your operating system. Therefore, no compilers remain that can compile this port, so you cannot compile this port on your operating system.

That is what the message means, but in fact it is not entirely true in this case.

Specifically, the sam2p port declares that it is incompatible with all version of the clang compiler, and the clang compiler is the only compiler that comes with Xcode 5 and later.

Older compilers exist in MacPorts, with which sam2p would be compatible: llvm-gcc42 and apple-gcc42. However, at the time that MacPorts 2.3.3 was released, llvm-gcc42 and apple-gcc42 could not be built on Yosemite, so MacPorts does not include those compilers in the list of fallback compilers.

The problems with llvm-gcc42 and apple-gcc42 have since been fixed. They now build and work on Yosemite. MacPorts has been updated (in r136965) to now use those as fallbacks again on Yosemite. However, a new version of MacPorts has not been released since then.

Until a new version of MacPorts is released containing this fix, you should be able to force MacPorts to use llvm-gcc42 for sam2p as follows:

sudo port clean sam2p
sudo port install sam2p configure.compiler=macports-llvm-gcc-4.2

Another option is to upgrade your MacPorts installation to the latest development code from our svn repository, which contains the fix.