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// RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify -Wc++17-extensions %s
// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify -DEXT -Wc++17-extensions %s
struct [[nodiscard]] S {};
S get_s();
S& get_s_ref();
enum [[nodiscard]] E {};
E get_e();
[[nodiscard]] int get_i();
[[nodiscard]] volatile int &get_vi();
void f() {
get_s(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
get_i(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
get_vi(); // 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
get_s_ref();
(void)get_s();
(void)get_i();
(void)get_vi();
(void)get_e();
}
[[nodiscard]] volatile char &(*fp)();
void g() {
fp(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
// OK, warning suppressed.
(void)fp();
}
namespace PR31526 {
typedef E (*fp1)();
typedef S (*fp2)();
typedef S S_alias;
typedef S_alias (*fp3)();
typedef fp2 fp2_alias;
void f() {
fp1 one;
fp2 two;
fp3 three;
fp2_alias four;
one(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
two(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
three(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
four(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
// These are all okay because of the explicit cast to void.
(void)one();
(void)two();
(void)three();
(void)four();
}
} // namespace PR31526
#ifdef EXT
// expected-warning@4 {{use of the 'nodiscard' attribute is a C++17 extension}}
// expected-warning@8 {{use of the 'nodiscard' attribute is a C++17 extension}}
// expected-warning@11 {{use of the 'nodiscard' attribute is a C++17 extension}}
// expected-warning@12 {{use of the 'nodiscard' attribute is a C++17 extension}}
// expected-warning@28 {{use of the 'nodiscard' attribute is a C++17 extension}}
#endif
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