1*67e74705SXin Li // RUN: %clang_cc1 -std=c++1z -verify %s
2*67e74705SXin Li
sum(T...t)3*67e74705SXin Li template<typename ...T> constexpr auto sum(T ...t) { return (... + t); }
product(T...t)4*67e74705SXin Li template<typename ...T> constexpr auto product(T ...t) { return (t * ...); }
all(T...t)5*67e74705SXin Li template<typename ...T> constexpr auto all(T ...t) { return (true && ... && t); }
all2(T...t)6*67e74705SXin Li template<typename ...T> constexpr auto all2(T ...t) { return (t && ... && true); }
7*67e74705SXin Li
8*67e74705SXin Li int k1 = (1 + ... + 2); // expected-error {{does not contain any unexpanded parameter packs}}
9*67e74705SXin Li int k2 = (1 + ...); // expected-error {{does not contain any unexpanded parameter packs}}
10*67e74705SXin Li int k3 = (... + 2); // expected-error {{does not contain any unexpanded parameter packs}}
11*67e74705SXin Li
bad1()12*67e74705SXin Li template<int ...N> void bad1() { (N + ... + N); } // expected-error {{unexpanded parameter packs in both operands}}
13*67e74705SXin Li // FIXME: it would be reasonable to support this as an extension.
bad2()14*67e74705SXin Li template<int ...N> void bad2() { (2 * N + ... + 1); } // expected-error {{expression not permitted as operand}}
bad3()15*67e74705SXin Li template<int ...N> void bad3() { (2 + N * ... * 1); } // expected-error {{expression not permitted as operand}}
bad4(int (&...x)[N])16*67e74705SXin Li template<int ...N, int ...M> void bad4(int (&...x)[N]) { (N + M * ... * 1); } // expected-error {{expression not permitted as operand}}
fixed4(int (&...x)[N])17*67e74705SXin Li template<int ...N, int ...M> void fixed4(int (&...x)[N]) { ((N + M) * ... * 1); }
18*67e74705SXin Li
19*67e74705SXin Li // Parens are mandatory.
bad5()20*67e74705SXin Li template<int ...N> void bad5() { N + ...; } // expected-error {{expected expression}} expected-error +{{}}
bad6()21*67e74705SXin Li template<int ...N> void bad6() { ... + N; } // expected-error {{expected expression}}
bad7()22*67e74705SXin Li template<int ...N> void bad7() { N + ... + N; } // expected-error {{expected expression}} expected-error +{{}}
23*67e74705SXin Li
24*67e74705SXin Li // Must have a fold-operator in the relevant places.
bad8()25*67e74705SXin Li template<int ...N> int bad8() { return (N + ... * 3); } // expected-error {{operators in fold expression must be the same}}
bad9()26*67e74705SXin Li template<int ...N> int bad9() { return (3 + ... * N); } // expected-error {{operators in fold expression must be the same}}
bad10()27*67e74705SXin Li template<int ...N> int bad10() { return (3 ? ... : N); } // expected-error +{{}} expected-note {{to match}}
bad11()28*67e74705SXin Li template<int ...N> int bad11() { return (N + ... 0); } // expected-error {{expected a foldable binary operator}} expected-error {{expected expression}}
bad12()29*67e74705SXin Li template<int ...N> int bad12() { return (... N); } // expected-error {{expected expression}}
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