1 // RUN: %clang_cc1 -std=c++1z -verify %s
2
use_from_own_init()3 void use_from_own_init() {
4 auto [a] = a; // expected-error {{binding 'a' cannot appear in the initializer of its own decomposition declaration}}
5 }
6
7 // As a Clang extension, _Complex can be decomposed.
decompose_complex(_Complex float cf)8 float decompose_complex(_Complex float cf) {
9 static _Complex float scf;
10 auto &[sre, sim] = scf;
11 // ok, this is references initialized by constant expressions all the way down
12 static_assert(&sre == &__real scf);
13 static_assert(&sim == &__imag scf);
14
15 auto [re, im] = cf;
16 return re*re + im*im;
17 }
18
19 // As a Clang extension, vector types can be decomposed.
20 typedef float vf3 __attribute__((ext_vector_type(3)));
decompose_vector(vf3 v)21 float decompose_vector(vf3 v) {
22 auto [x, y, z] = v;
23 auto *p = &x; // expected-error {{address of vector element requested}}
24 return x + y + z;
25 }
26
27 struct S { int a, b; };
f(S s)28 constexpr int f(S s) {
29 auto &[a, b] = s;
30 return a * 10 + b;
31 }
32 static_assert(f({1, 2}) == 12);
33
g(S && s)34 constexpr bool g(S &&s) {
35 auto &[a, b] = s;
36 return &a == &s.a && &b == &s.b && &a != &b;
37 }
38 static_assert(g({1, 2}));
39
enclosing()40 void enclosing() {
41 struct S { int a; };
42 auto [n] = S(); // expected-note 2{{'n' declared here}}
43
44 struct Q { int f() { return n; } }; // expected-error {{reference to local binding 'n' declared in enclosing function}}
45 // FIXME: This is probably supposed to be valid, but we do not have clear rules on how it's supposed to work.
46 (void) [&] { return n; }; // expected-error {{reference to local binding 'n' declared in enclosing function}}
47 (void) [n] {}; // expected-error {{'n' in capture list does not name a variable}}
48 }
49
bitfield()50 void bitfield() {
51 struct { int a : 3, : 4, b : 5; } a;
52 auto &[x, y] = a;
53 auto &[p, q, r] = a; // expected-error {{decomposes into 2 elements, but 3 names were provided}}
54 }
55
for_range()56 void for_range() {
57 int x = 1;
58 for (auto[a, b] : x) { // expected-error {{invalid range expression of type 'int'; no viable 'begin' function available}}
59 a++;
60 }
61
62 int y[5];
63 for (auto[c] : y) { // expected-error {{cannot decompose non-class, non-array type 'int'}}
64 c++;
65 }
66 }
67
error_recovery()68 int error_recovery() {
69 auto [foobar]; // expected-error {{requires an initializer}}
70 return foobar_; // expected-error {{undeclared identifier 'foobar_'}}
71 }
72
73 // PR32172
dependent_foreach(T t)74 template <class T> void dependent_foreach(T t) {
75 for (auto [a,b,c] : t)
76 a,b,c;
77 }
78
79 struct PR37352 {
80 int n;
fPR3735281 void f() { static auto [a] = *this; } // expected-error {{cannot be declared 'static'}}
82 };
83
84 namespace instantiate_template {
85
86 template <typename T1, typename T2>
87 struct pair {
88 T1 a;
89 T2 b;
90 };
91
92 const pair<int, int> &f1();
93
f2()94 int f2() {
95 const auto &[a, b] = f1();
96 return a + b;
97 }
98
99 } // namespace instantiate_template
100
101 // FIXME: by-value array copies
102