libgcc8 build fails due to "Atomic" error on Mojave

[physicsbeany]

Recently upgraded to MacOS Mojave from High Sierra, and followed general Macports instructions for migrating my old ports. Things went fine until libgcc8 (needed to do my py27-scipy installation). Initially, this failed because of Unwind issues. I solved this by following the advice in ticket #57198.

Now, however, the compilation fails because of an "Atomic" error. Specifically, the first instance of the Error in the log file is:

:info:build /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys/ucred.h:94:2: error: '_Atomic' does not name a type
:info:build   _Atomic u_long          cr_ref;  /* reference count */

The full logfile is 64 MB; I've uploaded the last 50K lines of it.

Some Googling indicates that this may be avoided by defining __STDC_NO_ATOMICS__, but I'm not certain this is the right answer (and I don't know how to do this as part of a Macports installation).

[physicsbeany]

last 50K lines of log file (whole thing is 64 MB)

[SerpentChris (Chris Calderon)]

I've got the same error on my brand new iMac running 10.14.4.

[kencu (Ken)]

This is a strange error to see. My first thought is to clean and try again ( I noticed you didn't clean between attempts previously, and this can have unforeseen weird effects).

sudo port clean libgcc8
sudo port -v install libgcc8

I'm also wondering why you didn't have it downloaded from the binary buildbot instead of MacPorts' making you build it. It's right there <​http://packages.macports.org/libgcc8/libgcc8-8.3.0_0.darwin_18.x86_64.tbz2>.

[ryandesign (Ryan Carsten Schmidt)]

Could you attach the entire logfile, compressing it first?