https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65733
--- Comment #3 from Jack Howarth <howarth.at.gcc at gmail dot com> --- As Iain pointed out to me, the gcc configure output under the more recent clang compilers isn't setting BUILD_CONFIG. Oddly gcc trunk also doesn't set BUILD_CONFIG in the configure output under the more recent clang compilers but the bootstrap comparison failure isn't seen. For gcc 4.9 and gcc-4_9-branch, --with-build-config=bootstrap-debug has to be explicitly passed to configure to suppress the bootstrap comparison failures under the more recent clang compilers.
