https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91947
--- Comment #13 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > It's done the same way as we've always created the > ${host_builddir}/c++config.h target, so I'm not sure why one is racy and the > other isn't. I didn't mean that the first one was not racy though ;-) But it has got only 3 >> while the new one has got 13 of them, so this can make a difference in practice. The issue happened on a Windows host for the 9 branch so you never know, but we never had such a thing before you had backported the change onto that branch.