https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117342
--- Comment #3 from David Binderman <dcb314 at hotmail dot com> --- No mention of base64 in the config.log: working.2 $ grep base64 config.log working.2 $ What's a combined build ? My usual configure line is: CC="clang" CXX="clang++" \ ../trunk/configure --prefix=$HOME/gcc/results.$DATE.asan.ubsan \ --disable-multilib \ --disable-bootstrap \ --with-build-config="bootstrap-asan bootstrap-ubsan" \ --with-pkgversion=$HASH \ --enable-checking=df,extra,fold,rtl,yes \ --disable-doc \ --enable-languages=c,c++,fortran Also: trunk $ pwd /home/dcb40b/gcc/trunk trunk $ grep base64 configure trunk $ git diff configure trunk $ So it doesn't look like any testing of .base64 in the configure I run and the configure is up to date.