https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120777
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Created attachment 61695 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61695&action=edit gcc16-pr120777-wip.patch Some further progress, the testcase now passes. Except uncommenting the last two lines still results in errors. I think there are 2 problems. One is that at the end of the complete constructor for E we get something like {.D.3067={._vptr.C=&_ZTV1E + 24, .c=47}, .D.3068={._vptr.D=&_ZTV1E + 72, .d=48, .D.2967={.D.2757={._vptr.A=&_ZTV1E + 128}}}, .e=49, .D.3073={.D.2757={._vptr.A=&_ZTV1B + 16, .a=45}, .b=46}} The problem is the D.2967= initialization there, I bet we need it during the construction, but maybe at the end of the complete ctor for a class with virtual bases we should remove all initializers in the CONSTRUCTOR which are beyond DECL_SIZE of the containing FIELD_DECL for bases. And the other are the abcu.C:183:13: error: ‘E{C{((& E::_ZTV1E) + 24), 45}, D{((& E::_ZTV1E) + 72), 45}, B{A{((& E::_ZTV1E) + 128), 43}, 42}}’ is not a constant expression 183 | constexpr E a; | ^ abcu.C:183:13: error: ‘((E*)(& a))->E::E()’ is not a constant expression because it refers to an incompletely initialized variable abcu.C:184:34: error: ‘E{C{((& E::_ZTV1E) + 24), 47}, D{((& E::_ZTV1E) + 72), 48}, 49, B{A{((& E::_ZTV1E) + 128), 45}, 46}}’ is not a constant expression 184 | constexpr E b (45, 46, 47, 48, 49); | ^ abcu.C:184:34: error: ‘((E*)(& b))->E::E(45, 46, 47, 48, 49)’ is not a constant expression because it refers to an incompletely initialized variable errors, perhaps on the other side we want to verify the bits beyond DECL_SIZE of FIELD_DECLs aren't initialized rather than flagging them as incompletely initialized.
