97 lines · cpp
1// RUN: %clang_cc1 -std=c++1z -verify %s2 3template<typename ...T> constexpr auto sum(T ...t) { return (... + t); }4template<typename ...T> constexpr auto product(T ...t) { return (t * ...); }5template<typename ...T> constexpr auto all(T ...t) { return (true && ... && t); }6template<typename ...T> constexpr auto all2(T ...t) { return (t && ... && true); }7 8int k1 = (1 + ... + 2); // expected-error {{does not contain any unexpanded parameter packs}}9int k2 = (1 + ...); // expected-error {{does not contain any unexpanded parameter packs}}10int k3 = (... + 2); // expected-error {{does not contain any unexpanded parameter packs}}11 12struct A { A(int); friend A operator+(A, A); A operator-(A); A operator()(A); A operator[](A); };13A operator*(A, A);14 15template<int ...N> void bad1() { (N + ... + N); } // expected-error {{unexpanded parameter packs in both operands}}16// FIXME: it would be reasonable to support this as an extension.17template<int ...N> void bad2() { (2 * N + ... + 1); } // expected-error {{expression not permitted as operand}}18template<int ...N> void bad3() { (2 + N * ... * 1); } // expected-error {{expression not permitted as operand}}19template<int ...N, int ...M> void bad4(int (&...x)[N]) { (N + M * ... * 1); } // expected-error {{expression not permitted as operand}}20template<int ...N, int ...M> void fixed4(int (&...x)[N]) { ((N + M) * ... * 1); }21template<typename ...T> void bad4a(T ...t) { (t * 2 + ... + 1); } // expected-error {{expression not permitted as operand}}22template<int ...N> void bad4b() { (A(0) + A(N) + ...); } // expected-error {{expression not permitted as operand}}23template<int ...N> void bad4c() { (A(0) - A(N) + ...); } // expected-error {{expression not permitted as operand}}24template<int ...N> void bad4d() { (A(0)(A(0)) + ... + A(0)[A(N)]); }25 26// Parens are mandatory.27template<int ...N> void bad5() { N + ...; } // expected-error {{expected expression}} expected-error +{{}}28template<int ...N> void bad6() { ... + N; } // expected-error {{expected expression}}29template<int ...N> void bad7() { N + ... + N; } // expected-error {{expected expression}} expected-error +{{}}30 31// Must have a fold-operator in the relevant places.32template<int ...N> int bad8() { return (N + ... * 3); } // expected-error {{operators in fold expression must be the same}}33template<int ...N> int bad9() { return (3 + ... * N); } // expected-error {{operators in fold expression must be the same}}34template<int ...N> int bad10() { return (3 ? ... : N); } // expected-error +{{}} expected-note {{to match}}35template<int ...N> int bad11() { return (N + ... 0); } // expected-error {{expected a foldable binary operator}} expected-error {{expected expression}}36template<int ...N> int bad12() { return (... N); } // expected-error {{expected expression}}37 38template<typename ...T> void as_operand_of_cast(int a, T ...t) {39 return40 (int)(a + ... + undeclared_junk) + // expected-error {{undeclared}}41 (int)(t + ... + undeclared_junk) + // expected-error {{undeclared}}42 (int)(... + undeclared_junk) + // expected-error {{undeclared}}43 (int)(undeclared_junk + ...) + // expected-error {{undeclared}}44 (int)(a + ...) + // expected-error {{does not contain any unexpanded}}45 (int)(a, ...) + // expected-error {{does not contain any unexpanded}}46 (int)(..., a) + // expected-error {{does not contain any unexpanded}}47 (int)(a, ..., undeclared_junk) + // expected-error {{undeclared}}48 (int)(t, ...) +49 (int)(..., t) +50 (int)(t, ..., a);51}52 53// fold-operator can be '>' or '>>'.54template <int... N> constexpr bool greaterThan() { return (N > ...); }55// expected-error@-1 {{comparison in fold expression}}56 57template <int... N> constexpr int rightShift() { return (N >> ...); }58 59static_assert(greaterThan<2, 1>()); // expected-note {{in instantiation}}60static_assert(rightShift<10, 1>() == 5);61 62template <auto V> constexpr auto Identity = V;63 64// Support fold operators within templates.65template <int... N> constexpr int nestedFoldOperator() {66 return Identity<(Identity<0> >> ... >> N)> +67 Identity<(N >> ... >> Identity<0>)>;68}69 70static_assert(nestedFoldOperator<3, 1>() == 1);71 72// A fold-expression is a primary-expression.73template <typename T, typename... Ts>74constexpr auto castSum(Ts... Args) {75 return (T)(Args + ...).Value; // expected-error{{member reference base type 'int' is not a structure or union}}76}77 78template <typename... Ts>79constexpr auto simpleSum(Ts... Args) {80 return (... + Args).Value; // expected-error{{member reference base type 'int' is not a structure or union}}81}82 83void prim() {84 castSum<int>(1, 2);85 // expected-note@-1{{in instantiation of function template specialization}}86 simpleSum(1, 2);87 // expected-note@-1{{in instantiation of function template specialization}}88 89 struct Number {90 int Value;91 constexpr Number operator+(Number Rhs) const { return {Rhs.Value + Value}; }92 };93 94 static_assert(castSum<long>(Number{1}, Number{2}) == 3);95 static_assert(simpleSum(Number{1}, Number{2}) == 3);96}97