Warning: All compilers are either blacklisted or unavailable

Ryan Schmidt ryandesign at macports.org
Thu Dec 31 18:47:52 UTC 2020

On Dec 31, 2020, at 03:12, Michael Newman wrote:

> Some months ago I upgraded the OS on a remote 2010 MacBook (the white one) to High Sierra (10.13.16). After the upgrade I did the recommended MacPorts migration without problems.
> I don’t visit this machine very regularly, so only recently remembered to run port clean all after doing a selfupdate/upgrade. Both of the latter ran without error, but the clean produced many like the following:
> --->  Cleaning wxsvg
> Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
> I’m not sure how to deal with this. There’s no indication that any ports failed to build, but the presence of the warning bothers me. I don’t see any recent list mentions of this issue.
> Is there anything that I should do?
> (Sorry for the New Year’s Eve interruption.)

If you see this warning when doing actions other than configuring/building/installing (such as when cleaning) ignore it. Maybe we shouldn't even display the warning in those cases, though I'm not sure if there's a good way for us to do that.

If you see it while configuring/building/installing, then here's an explanation of why the warning appears and what to do about it.

MacPorts has a list of possible compilers that ports could use to compile, which varies based on various criteria including Xcode version.

Individual ports can blacklist compilers from that list if they are known not to work for that port. MacPorts then picks the next best compiler from its list.

Ports can also add additional compilers to the list of possible compilers if needed.

If a port blacklists all of the compilers in the list, that means no compilers remain that can compile this software. MacPorts prints the warning you saw in this case. It is expected that trying to build the port in this situation will fail. If the build does not fail, that means the port's blacklist is incorrect (it claims a compiler won't work but it actually did) and should be fixed. File a bug report and provide as much information as possible about your OS version, Xcode version, and which compiler got used.

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