if (lookupStdTypeTraitMember(S, R, Loc, "tuple_size", Args, /*DiagID*/0))
return IsTupleLike::NotTupleLike;
- // FIXME: According to the standard, we're not supposed to diagnose if any
- // of the steps below fail (or if lookup for ::value is ambiguous or otherwise
- // results in an error), but this is subject to a pending CWG issue / NB
- // comment, which says we do diagnose if tuple_size<T> is complete but
- // tuple_size<T>::value is not an ICE.
+ // If we get this far, we've committed to the tuple interpretation, but
+ // we can still fail if there actually isn't a usable ::value.
struct ICEDiagnoser : Sema::VerifyICEDiagnoser {
LookupResult &R;
namespace std { template<typename T> struct tuple_size; }
void no_tuple_size_2() { auto [x, y] = A(); } // ok, decompose elementwise
-struct Bad1 {};
+struct Bad1 { int a, b; };
template<> struct std::tuple_size<Bad1> {};
void no_tuple_size_3() { auto [x, y] = Bad1(); } // expected-error {{cannot decompose this type; 'std::tuple_size<Bad1>::value' is not a valid integral constant expression}}