https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95593
Bug ID: 95593
Summary: [c++20] decltype() on consteval compiles invalid code
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: bruck.michael at gmail dot com
Target Milestone: ---
https://gcc.godbolt.org/z/24novC
This is from N4835 ([expr.const] after 14.7) and does not fail as required:
struct N {
constexpr N() {}
N(N const&) = delete;
};
template<typename T> constexpr void bad_assert_copyable() { T t; T t2 = t; }
using ineffective = decltype(bad_assert_copyable<N>());
// bad_assert_copyable<N> is not needed for constant evaluation
// (and thus not instantiated)
template<typename T> consteval void assert_copyable() { T t; T t2 = t; }
using check = decltype(assert_copyable<N>());
// error: assert_copyable<N> is instantiated (because it is needed for constant
// evaluation), but the attempt to copy t is ill-formed
