> Something starting with “error:”, I guess.
>
>
The only thing with in an error in that part of the message is the one that
says collect2: error: ld returned with exit status 1,the really generic gcc
linker error.


> The actual directory name depends on your --localstatedir or --prefix
> option passed to ‘configure’.  Can you check the value of
> ‘localstatedir’ in the config.log file?
>

It was hiding in /usr/local/var/nix, but unfortunately there's also no
substitute-binaries dir in there either!