https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66686
Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |msebor at gcc dot gnu.org --- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> --- The code doesn't look valid to me: Y is not a valid template argument for the template template parameter C. Of the compilers I tried GCC, EDG eccp, and IBM XLC++ all reject it (the latter two with a clear error message confirming the above). Clang is the only one that accepts it.