http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56641
Jason Merrill <jason at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jason at gcc dot gnu.org --- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> 2013-03-17 19:24:45 UTC --- The compiler is working as intended; the warning is there because if E and A are included in multiple translation units, the A type changes between translation units, creating an ODR violation. Without the #1 line, the compiler doesn't warn because the types are being defined in the main input file rather than an #included file.