https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67364
--- Comment #12 from Louis Dionne <ldionne.2 at gmail dot com> ---
The following code still fails to compile on GCC trunk:
template <typename Xn>
struct tuple {
Xn storage_;
constexpr tuple(Xn const& xn)
: storage_(xn)
{ }
template <typename ...dummy>
constexpr tuple(tuple const& other)
: storage_(other.storage_)
{ }
template <typename ...dummy>
constexpr tuple(tuple& other)
: tuple(const_cast<tuple const&>(other))
{ }
};
template <typename T>
struct wrapper { T value; };
template <typename T>
constexpr wrapper<T> wrap(T t) { return {t}; }
constexpr wrapper<tuple<int>> t = wrap(tuple<int>{2});
static_assert(t.value.storage_ == 2, "");
The error is
prog.cc:27:5: error: non-constant condition for static assertion
static_assert(t.value.storage_ == 2, "");
^~~~~~~~~~~~~
prog.cc:27:5: error: accessing uninitialized member 'tuple<int>::storage_'
Note that if the `static_assert` is changed to a runtime assertion, and if `t`
is not made `constexpr`, this code will trigger a runtime error. I'm pretty
sure
the above is triggered by the current bug.
