https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101460
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-07-15
Ever confirmed|0 |1
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I suppose the problem here is that the failed constant evaluation of frob<-1>()
only happens as a result of trying to use it as a template argument (where a
constant expression is required) which doesn't happen until overload resolution
is performed. So we have to at least being doing OR before we get a problem.
But maybe we can remember that it failed once, and so stop trying. If it's not
a valid constant expression, *that* is the error, not the fact that none of the
get<N> overloads can be called with an invalid constant expression.
Even if I change the code to do this it keeps trying overload resolution for
get<n>:
template<int N> void get_n(tuple& t) {
constexpr unsigned n = frob<N>();
get<n>(t);
}
The constexpr initialization of 'n' failed with a static_assert *and* a
non-constant narrowing conversion, so why do we continue and even attempt
overload resolution for 'get'?
