1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
| // RUN: %clang_cc1 -fsyntax-only -Wself-assign-field -verify %s
struct C {
int a;
int b;
void f() {
a = a; // expected-warning {{assigning field to itself}}
b = b; // expected-warning {{assigning field to itself}}
a = b;
this->a = a; // expected-warning {{assigning field to itself}}
this->b = b; // expected-warning {{assigning field to itself}}
a = this->a; // expected-warning {{assigning field to itself}}
b = this->b; // expected-warning {{assigning field to itself}}
this->a = this->a; // expected-warning {{assigning field to itself}}
this->b = this->b; // expected-warning {{assigning field to itself}}
a = b;
a = this->b;
this->a = b;
this->a = this->b;
a *= a;
a /= a;
a %= a;
a += a;
a -= a;
a <<= a;
a >>= a;
a &= a;
a |= a;
a ^= a;
}
void false_positives() {
#define OP =
#define LHS a
#define RHS a
// These shouldn't warn due to the use of the preprocessor.
a OP a;
LHS = a;
a = RHS;
LHS OP RHS;
#undef OP
#undef LHS
#undef RHS
// A way to silence the warning.
a = (int &)a;
}
// Do not diagnose self-assigment in an unevaluated context
void false_positives_unevaluated_ctx() noexcept(noexcept(a = a)) // expected-warning {{expression with side effects has no effect in an unevaluated context}}
{
decltype(a = a) b = a; // expected-warning {{expression with side effects has no effect in an unevaluated context}}
static_assert(noexcept(a = a), ""); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
static_assert(sizeof(a = a), ""); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
}
volatile int vol_a;
void vol_test() {
// Volatile stores aren't side-effect free.
vol_a = vol_a;
volatile int &vol_a_ref = vol_a;
vol_a_ref = vol_a_ref;
}
};
// Dummy type.
struct Dummy {};
template <typename T>
struct TemplateClass {
T var;
void f() {
var = var; // expected-warning {{assigning field to itself}}
}
};
void instantiate() {
{
TemplateClass<int> c;
c.f();
}
{
TemplateClass<Dummy> c;
c.f();
}
}
// It may make sense not to warn on the rest of the tests.
// It may be a valid use-case to self-assign to tell the compiler that
// it is ok to vectorize the store.
void f0(C *s, C *t) {
s->a = s->a;
t->a = s->a;
}
void f1(C &s, C &t) {
s.a = s.a;
t.a = s.a;
}
struct T {
C *s;
};
void f2(T *t, T *t2) {
t->s->a = t->s->a;
t2->s->a = t->s->a;
}
void f3(T &t, T &t2) {
t.s->a = t.s->a;
t2.s->a = t.s->a;
}
|