[Bug libstdc++/94811] Please make make_tuple noexcept when possible

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94811

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Rafael Avila de Espindola from comment #0)
> So it should be possible to make the std::tuple constructor and

Isn't that already done?

> std::make_tuple noexcept when the arguments have noexcept copy or move
> constructors.

make_tuple should depend on the tuple being constructed, not on the individual
elements, because make_tuple is constructing a tuple, not constructing the
elements.

But I think this is slightly complicated by guaranteed copy elision in C++17.
For C++14 the make_tuple function depends on whether constructing the tuple can
throw *and* whether copying the return value can throw, for C++17 it only
depends on the former.