| #include <cstdio> |
| #include <string> |
| #include <vector> |
| |
| // If we have libc++ 4.0 or greater we should have <variant> |
| // According to libc++ C++1z status page https://libcxx.llvm.org/cxx1z_status.html |
| #if _LIBCPP_VERSION >= 4000 |
| #include <variant> |
| #define HAVE_VARIANT 1 |
| #else |
| #define HAVE_VARIANT 0 |
| #endif |
| |
| struct S { |
| operator int() { throw 42; } |
| } ; |
| |
| |
| int main() |
| { |
| bool has_variant = HAVE_VARIANT ; |
| |
| printf( "%d\n", has_variant ) ; // break here |
| |
| #if HAVE_VARIANT == 1 |
| std::variant<int, double, char> v1; |
| std::variant<int, double, char> &v1_ref = v1; |
| std::variant<int, double, char> v2; |
| std::variant<int, double, char> v3; |
| std::variant<std::variant<int,double,char>> v_v1 ; |
| std::variant<int, double, char> v_no_value; |
| |
| v1 = 12; // v contains int |
| v_v1 = v1 ; |
| int i = std::get<int>(v1); |
| printf( "%d\n", i ); // break here |
| |
| v2 = 2.0 ; |
| double d = std::get<double>(v2) ; |
| printf( "%f\n", d ); |
| |
| v3 = 'A' ; |
| char c = std::get<char>(v3) ; |
| printf( "%d\n", c ); |
| |
| // Checking v1 above and here to make sure we done maintain the incorrect |
| // state when we change its value. |
| v1 = 2.0; |
| d = std::get<double>(v1) ; |
| printf( "%f\n", d ); // break here |
| |
| try { |
| v_no_value.emplace<0>(S()); |
| } catch( ... ) {} |
| |
| printf( "%zu\n", v_no_value.index() ) ; |
| #endif |
| |
| return 0; // break here |
| } |