https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111895
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:6fa7284e2824310bb7204d41b5243c677ecb62d3 commit r14-4902-g6fa7284e2824310bb7204d41b5243c677ecb62d3 Author: Marek Polacek <pola...@redhat.com> Date: Mon Oct 23 17:06:45 2023 -0400 c++: error with bit-fields and scoped enums [PR111895] Here we issue a bogus error: invalid operands of types 'unsigned char:2' and 'int' to binary 'operator!=' when casting a bit-field of scoped enum type to bool. In build_static_cast_1, perform_direct_initialization_if_possible returns NULL_TREE, because the invented declaration T t(e) fails, which is correct. So we go down to ocp_convert, which has code to deal with this case: /* We can't implicitly convert a scoped enum to bool, so convert to the underlying type first. */ if (SCOPED_ENUM_P (intype) && (convtype & CONV_STATIC)) e = build_nop (ENUM_UNDERLYING_TYPE (intype), e); but the SCOPED_ENUM_P is false since intype is <unnamed-unsigned:2>. This could be fixed by using unlowered_expr_type. But then c_common_truthvalue_conversion/CASE_CONVERT has a similar problem, and unlowered_expr_type is a C++-only function. Rather than adding a dummy unlowered_expr_type to C, I think we should follow [expr.static.cast]p3: "the lvalue-to-rvalue conversion is applied to the bit-field and the resulting prvalue is used as the operand of the static_cast." There are no prvalue bit-fields, so the l-to-r conversion performed in decay_conversion will get us an expression whose type is the enum. PR c++/111895 gcc/cp/ChangeLog: * typeck.cc (build_static_cast_1): Call decay_conversion. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/scoped_enum12.C: New test.
