[Bug target/81797] gcc 7.1.0 fails to build on macOS 10.13 (High Sierra):

[misty at brew dot sh]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797

--- Comment #9 from Misty De Meo <misty at brew dot sh> ---
My VM has two cores, and repros this problem.

I reported this to Apple, who assigned the bug ID rdar://33924943. It was
reported to me that Apple engineers believed it was fixed in the latest beta,
but it is still reproducing.