https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91692
--- Comment #2 from Ian Lance Taylor <ian at airs dot com> --- Thanks for the bug report. The normal case when configuring GCC is to create a new empty directory and run SRCDIR/configure in that directory, as documented at https://gcc.gnu.org/install/configure.html. Your suggested patch will break that normal case. The case of running ./configure should also work, but is rarely tested. Clearly there is something wrong in that case that will need to be fixed.
