I just pulled down sources at about 10:00 am BST. Here is the follow error:
# create libstdc++-v3/cow-fs_dir.d
...
In file included from usr/src/external/gpl3/gcc/dist/libstdc++-v3/src/c++17/cow-fs_dir.cc:26: /libstdc++-v3/src/c++17/fs_dir.cc:29:10: fatal error: bits/largefile-config.h: No such file or directory
29 | #include <bits/largefile-config.h>
| ^~~~~~~~~~~~~~~~~
compilation terminated.
nbmakedep: compile failed.