On 11/11/19 7:54 PM, Marek Polacek wrote:
Part of P1327R1 is to allow typeid with an operand of polymorphic type in constexpr. I found that we pretty much support it already, the only tweak was to allow TYPEID_EXPR (only created in a template) in constexpr in C++20.I also noticed this in build_typeid: /* FIXME when integrating with c_fully_fold, mark resolves_to_fixed_type_p case as a non-constant expression. */ if (TYPE_POLYMORPHIC_P (TREE_TYPE (exp)) && ! resolves_to_fixed_type_p (exp, &nonnull) && ! nonnull) but I'm not quite sure what to do with it.
Remove it, I think.
Bootstrapped/regtested on x86_64-linux, ok for trunk? 2019-11-11 Marek Polacek <pola...@redhat.com> PR c++/88337 - P1327R1: Allow polymorphic typeid in constexpr. * constexpr.c (potential_constant_expression_1): Allow a typeid expression whose operand is of polymorphic type in constexpr in C++20. * g++.dg/cpp2a/constexpr-typeid1.C: New test. * g++.dg/cpp2a/constexpr-typeid2.C: New test. * g++.dg/cpp2a/constexpr-typeid3.C: New test. * g++.dg/cpp2a/constexpr-typeid4.C: New test. diff --git gcc/cp/constexpr.c gcc/cp/constexpr.c index 20fddc57825..430c65694b7 100644 --- gcc/cp/constexpr.c +++ gcc/cp/constexpr.c @@ -7018,11 +7018,13 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, return false;case TYPEID_EXPR:- /* -- a typeid expression whose operand is of polymorphic - class type; */ + /* In C++20, a typeid expression whose operand is of polymorphic + class type can be constexpr. */ { tree e = TREE_OPERAND (t, 0); - if (!TYPE_P (e) && !type_dependent_expression_p (e) + if (cxx_dialect < cxx2a
Do we want to allow this before C++20 if !strict? OK either way. Jason
