70 lines · c
1// RUN: %clang_cc1 -std=c2x -fsyntax-only -verify -Wno-unused %s2// RUN: %clang_cc1 -fsyntax-only -verify=expected,cpp -Wno-unused -x c++ -std=c++17 %s3 4// Test various parsing situations for the Clang extension to _Generic which5// accepts a type name instead of an expression as the first operand.6 7int foo();8 9void test() {10 // We can parse a simple type name.11 _Generic(int, int : 0);12 13 // We can also parse tag types.14 struct S { int i; };15 enum E { A };16 union U { int i; };17 _Generic(struct S, default : 0);18 _Generic(enum E, default : 0);19 _Generic(union U, default : 0);20 21 // We can also parse array types.22 _Generic(int[12], default : 0);23 24 // And pointer to array types, too.25 _Generic(int(*)[12], default : 0);26 27 // We do not accept a parenthesized type name.28 _Generic((int), int : 0); // expected-error {{expected expression}}29 30 // We can parse more complex types as well. Note, this is a valid spelling of31 // a function pointer type in C but is not a valid spelling of a function32 // pointer type in C++. Surprise!33 _Generic(__typeof__(foo())(*)(__typeof__(&foo)), int (*)(int (*)()) : 0); // cpp-error {{expected expression}} \34 cpp-error {{expected '(' for function-style cast or type construction}}35 36 // C being the magical language that it is, lets you define a type anywhere37 // you can spell a type.38 _Generic(struct T { int a; }, default : 0); // cpp-error {{'T' cannot be defined in a type specifier}}39}40 41#ifdef __cplusplus42template <typename Ty>43struct S {44 template <template <typename> typename Uy>45 struct T {46 typedef typename Uy<Ty>::type foo;47 };48};49 50template <typename Ty>51struct inst {52 typedef Ty type;53};54 55void cpp_test() {56 // Ensure we can parse more complex C++ typenames as well.57 _Generic(S<int>::T<inst>::foo, int : 1);58 59 // And that the type name doesn't confuse us when given an initialization60 // expression.61 _Generic(S<int>::T<inst>::foo{}, int : 1);62}63 64template <typename Ty, int N = _Generic(Ty, int : 0, default : 1)>65constexpr Ty bar() { return N; }66 67static_assert(bar<int>() == 0);68static_assert(bar<float>() == 1);69#endif // __cplusplus70