warn-unused-result.cpp revision 51ceb7bab599ea7d39d290ff5e88e4a1f0f5bc5c 
1// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
2
3int f() __attribute__((warn_unused_result));
4
5struct S {
6  void t() const;
7};
8S g1() __attribute__((warn_unused_result));
9S *g2() __attribute__((warn_unused_result));
10S &g3() __attribute__((warn_unused_result));
11
12void test() {
13  f(); // expected-warning {{ignoring return value}}
14  g1(); // expected-warning {{ignoring return value}}
15  g2(); // expected-warning {{ignoring return value}}
16  g3(); // expected-warning {{ignoring return value}}
17
18  (void)f();
19  (void)g1();
20  (void)g2();
21  (void)g3();
22
23  if (f() == 0) return;
24
25  g1().t();
26  g2()->t();
27  g3().t();
28
29  int i = f();
30  S s1 = g1();
31  S *s2 = g2();
32  S &s3 = g3();
33  const S &s4 = g1();
34}
35
36struct X {
37 int foo() __attribute__((warn_unused_result));
38};
39
40void bah() {
41  X x, *x2;
42  x.foo(); // expected-warning {{ignoring return value}}
43  x2->foo(); // expected-warning {{ignoring return value}}
44}
45
46namespace warn_unused_CXX11 {
47struct [[warn_unused_result]] Status {
48  bool ok() const;
49};
50Status DoSomething();
51Status& DoSomethingElse();
52Status* DoAnotherThing();
53Status** DoYetAnotherThing();
54void lazy() {
55  Status s = DoSomething();
56  if (!s.ok()) return;
57  Status &rs = DoSomethingElse();
58  if (!rs.ok()) return;
59  Status *ps = DoAnotherThing();
60  if (!ps->ok()) return;
61  Status **pps = DoYetAnotherThing();
62  if (!(*pps)->ok()) return;
63
64  (void)DoSomething();
65  (void)DoSomethingElse();
66  (void)DoAnotherThing();
67  (void)DoYetAnotherThing();
68
69  DoSomething(); // expected-warning {{ignoring return value}}
70  DoSomethingElse(); // expected-warning {{ignoring return value}}
71  DoAnotherThing(); // expected-warning {{ignoring return value}}
72  DoYetAnotherThing();
73}
74}
75