https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95009
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:e3fab19a79e3dc3cdf3e54ca20107e1dc15a3927 commit r11-9363-ge3fab19a79e3dc3cdf3e54ca20107e1dc15a3927 Author: Marek Polacek <pola...@redhat.com> Date: Sat Dec 4 12:07:41 2021 -0500 c++: Fix for decltype and bit-fields [PR95009] Here, decltype deduces the wrong type for certain expressions involving bit-fields. Unlike in C, in C++ bit-field width is explicitly not part of the type, so I think decltype should never deduce to 'int:N'. The problem isn't that we're not calling unlowered_expr_type--we are--it's that is_bitfield_expr_with_lowered_type only handles certain codes, but not others. For example, += works fine but ++ does not. This also fixes decltype-bitfield2.C where we were crashing (!), but unfortunately it does not fix 84516 or 70733 where the problem is likely a missing call to unlowered_expr_type. It occurs to me now that typeof likely has had the same issue, but this patch should fix that too. PR c++/95009 gcc/cp/ChangeLog: * typeck.c (is_bitfield_expr_with_lowered_type) <case MODIFY_EXPR>: Handle UNARY_PLUS_EXPR, NEGATE_EXPR, NON_LVALUE_EXPR, BIT_NOT_EXPR, P*CREMENT_EXPR too. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/decltype-bitfield1.C: New test. * g++.dg/cpp0x/decltype-bitfield2.C: New test. (cherry picked from commit 3a2257e6b3fa288d6c50831987949b9ff7dfb865)
