1 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wunused-value %s
2
3 void f() __attribute__((const));
4
5 namespace PR18571 {
6 // Unevaluated contexts should not trigger unused result warnings.
7 template <typename T>
foo(T)8 auto foo(T) -> decltype(f(), bool()) { // Should not warn.
9 return true;
10 }
11
g()12 void g() {
13 foo(1);
14 }
15
h()16 void h() {
17 int i = 0;
18 (void)noexcept(++i); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
19 decltype(i++) j = 0; // expected-warning {{expression with side effects has no effect in an unevaluated context}}
20 }
21
22 struct S {
23 S operator++(int);
24 S(int i);
25 S();
26
27 int& f();
28 S g();
29 };
30
j()31 void j() {
32 S s;
33 int i = 0;
34 (void)noexcept(s++); // Ok
35 (void)noexcept(i++); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
36 (void)noexcept(i = 5); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
37 (void)noexcept(s = 5); // Ok
38
39 (void)sizeof(s.f()); // Ok
40 (void)sizeof(s.f() = 5); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
41 (void)noexcept(s.g() = 5); // Ok
42 }
43
44 }