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
|
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -fcxx-exceptions %s
// RUN: %clang_cc1 -fsyntax-only -std=c++11 -fcxx-exceptions -Wno-invalid-constexpr %s
namespace StdExample {
constexpr int f(void *) { return 0; }
constexpr int f(...) { return 1; }
constexpr int g1() { return f(0); }
constexpr int g2(int n) { return f(n); }
constexpr int g3(int n) { return f(n*0); }
namespace N {
constexpr int c = 5;
constexpr int h() { return c; }
}
constexpr int c = 0;
constexpr int g4() { return N::h(); }
static_assert(f(0) == 0, "");
static_assert(f('0') == 1, "");
static_assert(g1() == 0, "");
static_assert(g2(0) == 1, "");
static_assert(g2(1) == 1, "");
static_assert(g3(0) == 1, "");
static_assert(g3(1) == 1, "");
static_assert(N::h() == 5, "");
static_assert(g4() == 5, "");
constexpr int f(bool b)
{ return b ? throw 0 : 0; } // ok
constexpr int f() { return throw 0, 0; } // expected-error {{constexpr function never produces a constant expression}} expected-note {{subexpression}}
struct B {
constexpr B(int x) : i(0) { }
int i;
};
int global; // expected-note {{declared here}}
struct D : B {
constexpr D() : B(global) { } // expected-error {{constexpr constructor never produces a constant expression}} expected-note {{read of non-const}}
};
}
namespace PotentialConstant {
constexpr int Comma(int n) { return // expected-error {{constexpr function never produces a constant expression}}
(void)(n * 2),
throw 0, // expected-note {{subexpression}}
0;
}
int ng; // expected-note 6{{here}}
constexpr int BinaryOp1(int n) { return n + ng; } // expected-error {{never produces}} expected-note {{read}}
constexpr int BinaryOp2(int n) { return ng + n; } // expected-error {{never produces}} expected-note {{read}}
double dg; // expected-note 2{{here}}
constexpr double BinaryOp1(double d) { return d + dg; } // expected-error {{never produces}} expected-note {{read}}
constexpr double BinaryOp2(double d) { return dg + d; } // expected-error {{never produces}} expected-note {{read}}
constexpr int Add(int a, int b, int c) { return a + b + c; }
constexpr int FunctionArgs(int a) { return Add(a, ng, a); } // expected-error {{never produces}} expected-note {{read}}
struct S { int a; int b; int c[2]; };
constexpr S InitList(int a) { return { a, ng }; }; // expected-error {{never produces}} expected-note {{read}}
constexpr S InitList1a(int a) { return S{ a, ng }; }; // expected-error {{never produces}} expected-note {{read}}
constexpr S InitList2(int a) { return { a, a, { ng } }; }; // expected-error {{never produces}} expected-note {{read}}
constexpr S InitList3(int a) { return a ? S{ a, a } : S{ a, ng }; }; // ok
constexpr int LogicalAnd1(int n) { return n && (throw, 0); } // ok
constexpr int LogicalAnd2(int n) { return 1 && (throw, 0); } // expected-error {{never produces}} expected-note {{subexpression}}
constexpr int LogicalOr1(int n) { return n || (throw, 0); } // ok
constexpr int LogicalOr2(int n) { return 0 || (throw, 0); } // expected-error {{never produces}} expected-note {{subexpression}}
constexpr int Conditional1(bool b, int n) { return b ? n : ng; } // ok
constexpr int Conditional2(bool b, int n) { return b ? n * ng : n + ng; } // expected-error {{never produces}} expected-note {{both arms of conditional operator are unable to produce a constant expression}}
// __builtin_constant_p ? : is magical, and is always a potential constant.
constexpr bool BcpCall(int n) {
return __builtin_constant_p((int*)n != &n) ? (int*)n != &n : (int*)n != &n;
}
static_assert(BcpCall(0), "");
// DR1311: A function template which can produce a constant expression, but
// for which a particular specialization cannot, is ok.
template<typename T> constexpr T cmin(T a, T b) {
return a < b ? a : b;
}
int n = cmin(3, 5); // ok
struct X {
constexpr X() {}
bool operator<(X); // not constexpr
};
X x = cmin(X(), X()); // ok, not constexpr
// Same with other temploids.
template<typename T>
struct Y {
constexpr Y() {}
constexpr int get() { return T(); }
};
struct Z { operator int(); };
int y1 = Y<int>().get(); // ok
int y2 = Y<Z>().get(); // ok
}
|
