1 // RUN: %clang_cc1 -std=c++1z -Wno-binding-in-condition -verify %s
2
3 struct X {
4 bool flag;
5 int data;
operator boolX6 constexpr explicit operator bool() const {
7 return flag;
8 }
operator intX9 constexpr operator int() const {
10 return data;
11 }
12 };
13
14 namespace CondInIf {
f(X x)15 constexpr int f(X x) {
16 if (auto [ok, d] = x)
17 return d + int(ok);
18 else
19 return d * int(ok);
20 ok = {}; // expected-error {{use of undeclared identifier 'ok'}}
21 d = {}; // expected-error {{use of undeclared identifier 'd'}}
22 }
23
24 static_assert(f({true, 2}) == 3);
25 static_assert(f({false, 2}) == 0);
26
g(char const (& x)[2])27 constexpr char g(char const (&x)[2]) {
28 if (auto &[a, b] = x)
29 return a;
30 else
31 return b;
32
33 if (auto [a, b] = x) // expected-error {{an array type is not allowed here}}
34 ;
35 }
36
37 static_assert(g("x") == 'x');
38 } // namespace CondInIf
39
40 namespace CondInSwitch {
f(int n)41 constexpr int f(int n) {
42 switch (X s = {true, n}; auto [ok, d] = s) {
43 s = {};
44 case 0:
45 return int(ok);
46 case 1:
47 return d * 10;
48 case 2:
49 return d * 40;
50 default:
51 return 0;
52 }
53 ok = {}; // expected-error {{use of undeclared identifier 'ok'}}
54 d = {}; // expected-error {{use of undeclared identifier 'd'}}
55 s = {}; // expected-error {{use of undeclared identifier 's'}}
56 }
57
58 static_assert(f(0) == 1);
59 static_assert(f(1) == 10);
60 static_assert(f(2) == 80);
61 } // namespace CondInSwitch
62
63 namespace CondInWhile {
f(int n)64 constexpr int f(int n) {
65 int m = 1;
66 while (auto [ok, d] = X{n > 1, n}) {
67 m *= d;
68 --n;
69 }
70 return m;
71 return ok; // expected-error {{use of undeclared identifier 'ok'}}
72 }
73
74 static_assert(f(0) == 1);
75 static_assert(f(1) == 1);
76 static_assert(f(4) == 24);
77 } // namespace CondInWhile
78
79 namespace CondInFor {
f(int n)80 constexpr int f(int n) {
81 int a = 1, b = 1;
82 for (X x = {true, n}; auto &[ok, d] = x; --d) {
83 if (d < 2)
84 ok = false;
85 else {
86 int x = b;
87 b += a;
88 a = x;
89 }
90 }
91 return b;
92 return d; // expected-error {{use of undeclared identifier 'd'}}
93 }
94
95 static_assert(f(0) == 1);
96 static_assert(f(1) == 1);
97 static_assert(f(2) == 2);
98 static_assert(f(5) == 8);
99 } // namespace CondInFor
100