1 // RUN: %clang_cc1 -std=c++1z -verify %s 2 3 template<typename ...T> constexpr auto sum(T ...t) { return (... + t); } 4 template<typename ...T> constexpr auto product(T ...t) { return (t * ...); } 5 template<typename ...T> constexpr auto all(T ...t) { return (true && ... && t); } 6 template<typename ...T> constexpr auto dumb(T ...t) { return (false && ... && t); } 7 8 static_assert(sum(1, 2, 3, 4, 5) == 15); 9 static_assert(product(1, 2, 3, 4, 5) == 120); 10 static_assert(!all(true, true, false, true, false)); 11 static_assert(all(true, true, true, true, true)); 12 static_assert(!dumb(true, true, true, true, true)); 13 14 struct S { 15 int a, b, c, d, e; 16 }; 17 template<typename ...T> constexpr auto increment_all(T &...t) { 18 (++t, ...); 19 } 20 constexpr bool check() { 21 S s = { 1, 2, 3, 4, 5 }; 22 increment_all(s.a, s.b, s.c, s.d, s.e); 23 return s.a == 2 && s.b == 3 && s.c == 4 && s.d == 5 && s.e == 6; 24 } 25 static_assert(check()); 26 27 template<int ...N> void empty() { 28 static_assert((N + ...) == 0); 29 static_assert((N * ...) == 1); 30 static_assert((N | ...) == 0); 31 static_assert((N & ...) == -1); 32 static_assert((N || ...) == false); 33 static_assert((N && ...) == true); 34 (N, ...); 35 } 36 template void empty<>(); 37 38 // An empty fold-expression isn't a null pointer just because it's an integer 39 // with value 0. 40 template<int ...N> void null_ptr() { 41 void *p = (N + ...); // expected-error {{rvalue of type 'int'}} 42 void *q = (N | ...); // expected-error {{rvalue of type 'int'}} 43 } 44 template void null_ptr<>(); // expected-note {{in instantiation of}} 45 46 template<int ...N> void bad_empty() { 47 (N - ...); // expected-error {{empty expansion for operator '-' with no fallback}} 48 (N / ...); // expected-error {{empty expansion for operator '/' with no fallback}} 49 (N % ...); // expected-error {{empty expansion for operator '%' with no fallback}} 50 (N = ...); // expected-error {{empty expansion for operator '=' with no fallback}} 51 } 52 template void bad_empty<>(); // expected-note {{in instantiation of}} 53 54 template<int ...N> void empty_with_base() { 55 extern int k; 56 (k = ... = N); // expected-warning{{unused}} 57 58 void (k = ... = N); // expected-error {{expected ')'}} expected-note {{to match}} 59 void ((k = ... = N)); 60 (void) (k = ... = N); 61 } 62 template void empty_with_base<>(); // expected-note {{in instantiation of}} 63 template void empty_with_base<1>(); 64 65 struct A { 66 struct B { 67 struct C { 68 struct D { 69 int e; 70 } d; 71 } c; 72 } b; 73 } a; 74 template<typename T, typename ...Ts> constexpr decltype(auto) apply(T &t, Ts ...ts) { 75 return (t.*....*ts); 76 } 77 static_assert(&apply(a, &A::b, &A::B::c, &A::B::C::d, &A::B::C::D::e) == &a.b.c.d.e); 78
