https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81911
TC <rs2740 at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |rs2740 at gmail dot com --- Comment #1 from TC <rs2740 at gmail dot com> --- The full-expression of the initialization of c0 includes the lvalue-to-rvalue conversion on someVar[0], which is not allowed in a core constant expression; see [expr.const]/2.7. Note that [expr.const]/2.7.1 only applies to complete objects, which someVar[0] is not (it's a subobject).