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
118
119
120
121
122
|
// RUN: %check_clang_tidy %s cppcoreguidelines-slicing %t
class Base {
int i;
void f() {}
virtual void g() {}
};
class DerivedWithMemberVariables : public Base {
void f();
int j;
};
class TwiceDerivedWithNoMemberVariables : public DerivedWithMemberVariables {
void f();
};
class DerivedWithOverride : public Base {
void f();
void g() override {}
};
class TwiceDerivedWithNoOverride : public DerivedWithOverride {
void f();
};
void TakesBaseByValue(Base base);
DerivedWithMemberVariables ReturnsDerived();
void positivesWithMemberVariables() {
DerivedWithMemberVariables b;
Base a{b};
// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state [cppcoreguidelines-slicing]
a = b;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
TakesBaseByValue(b);
// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
TwiceDerivedWithNoMemberVariables c;
a = c;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'TwiceDerivedWithNoMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
a = ReturnsDerived();
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
}
void positivesWithOverride() {
DerivedWithOverride b;
Base a{b};
// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: slicing object from type 'DerivedWithOverride' to 'Base' discards override 'g'
a = b;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithOverride' to 'Base' discards override 'g'
TakesBaseByValue(b);
// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: slicing object from type 'DerivedWithOverride' to 'Base' discards override 'g'
TwiceDerivedWithNoOverride c;
a = c;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithOverride' to 'Base' discards override 'g'
}
void TakesBaseByReference(Base &base);
class DerivedThatAddsVirtualH : public Base {
virtual void h();
};
class DerivedThatOverridesH : public DerivedThatAddsVirtualH {
void h() override;
};
void negatives() {
// OK, simple copying from the same type.
Base a;
TakesBaseByValue(a);
DerivedWithMemberVariables b;
DerivedWithMemberVariables c{b};
b = c;
// OK, derived type does not have extra state.
TwiceDerivedWithNoMemberVariables d;
DerivedWithMemberVariables e{d};
e = d;
// OK, derived does not override any method.
TwiceDerivedWithNoOverride f;
DerivedWithOverride g{f};
g = f;
// OK, no copying.
TakesBaseByReference(d);
TakesBaseByReference(f);
// Derived type overrides methods, but these methods are not in the base type,
// so cannot be called accidentally. Right now this triggers, but we might
// want to allow it.
DerivedThatOverridesH h;
a = h;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedThatOverridesH' to 'Base' discards override 'h'
}
namespace PR31187 {
// Don't warn when calling constructor of base virtual class, from
// initialization list of derived class constructor.
struct BaseA {
virtual ~BaseA() {}
virtual void foo() {}
int i;
};
struct BaseB : virtual BaseA {
virtual void foo() {}
};
struct ClassWithVirtualBases : BaseB {
ClassWithVirtualBases(const BaseB& other) : BaseA(other), BaseB(other) {}
ClassWithVirtualBases(const ClassWithVirtualBases& other) : BaseA(other), BaseB(other) {}
};
}
|
