| // RUN: %clang_cc1 -fsyntax-only -std=c2x -verify %s |
| |
| struct [[nodiscard]] S1 { // ok |
| int i; |
| }; |
| struct [[nodiscard nodiscard]] S2 { // expected-error {{attribute 'nodiscard' cannot appear multiple times in an attribute specifier}} |
| int i; |
| }; |
| struct [[nodiscard("Wrong")]] S3 { // FIXME: may need an extension warning. |
| int i; |
| }; |
| |
| struct S3 get_s3(void); |
| |
| [[nodiscard]] int f1(void); |
| enum [[nodiscard]] E1 { One }; |
| |
| [[nodiscard]] int i; // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}} |
| |
| struct [[nodiscard]] S4 { |
| int i; |
| }; |
| struct S4 get_s(void); |
| |
| enum [[nodiscard]] E2 { Two }; |
| enum E2 get_e(void); |
| |
| [[nodiscard]] int get_i(); |
| |
| void f2(void) { |
| get_s(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
| get_s3(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute: Wrong}} |
| get_i(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
| get_e(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
| |
| // Okay, warnings are not encouraged |
| (void)get_s(); |
| (void)get_s3(); |
| (void)get_i(); |
| (void)get_e(); |
| } |
| |
| struct [[nodiscard]] error_info{ |
| int i; |
| }; |
| |
| struct error_info enable_missile_safety_mode(void); |
| void launch_missiles(void); |
| void test_missiles(void) { |
| enable_missile_safety_mode(); // expected-warning {{ignoring return value of function declared with 'nodiscard'}} |
| launch_missiles(); |
| } |
| |