https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65175
--- Comment #2 from Ben Pope <ben at pope dot name> --- Using built-in specs. COLLECT_GCC=/usr/lib/gcc-snapshot/bin/g++ COLLECT_LTO_WRAPPER=/usr/lib/gcc-snapshot/libexec/gcc/x86_64-linux-gnu/5.0.0/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 20150211-0ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-snapshot/README.Bugs --enable-languages=c,ada,c++,java,go,fortran,objc,obj-c++ --prefix=/usr/lib/gcc-snapshot --enable-shared --enable-linker-build-id --disable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=c++98 --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5.0-snap-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5.0-snap-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5.0-snap-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64 --enable-multilib --with-tune=generic --enable-checking=yes --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 5.0.0 20150211 (experimental) [trunk revision 220605] (Ubuntu 20150211-0ubuntu1) b This one produces: /home/ben/development/test/ben_rxcpp/Rx/v2/src/rxcpp/rx-util.hpp:50:64: internal compiler error: tree check: expected var_decl or function_decl, have type_decl in duplicate_decls, at cp/decl.c:2135 using source_operator_type_t = typename T::source_operator_type;