| 1 | // RUN: %clang_cc1 -std=c++1z -verify %s |
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| 2 | |
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| 3 | void use_from_own_init() { |
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| 4 | auto [a] = a; // expected-error {{binding 'a' cannot appear in the initializer of its own decomposition declaration}} |
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| 5 | } |
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| 6 | |
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| 7 | // As a Clang extension, _Complex can be decomposed. |
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| 8 | float decompose_complex(_Complex float cf) { |
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| 9 | static _Complex float scf; |
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| 10 | auto &[sre, sim] = scf; |
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| 11 | // ok, this is references initialized by constant expressions all the way down |
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| 12 | static_assert(&sre == &__real scf); |
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| 13 | static_assert(&sim == &__imag scf); |
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| 14 | |
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| 15 | auto [re, im] = cf; |
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| 16 | return re*re + im*im; |
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| 17 | } |
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| 18 | |
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| 19 | // As a Clang extension, vector types can be decomposed. |
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| 20 | typedef float vf3 __attribute__((ext_vector_type(3))); |
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| 21 | float decompose_vector(vf3 v) { |
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| 22 | auto [x, y, z] = v; |
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| 23 | auto *p = &x; // expected-error {{address of vector element requested}} |
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| 24 | return x + y + z; |
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| 25 | } |
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| 26 | |
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| 27 | struct S { int a, b; }; |
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| 28 | constexpr int f(S s) { |
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| 29 | auto &[a, b] = s; |
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| 30 | return a * 10 + b; |
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| 31 | } |
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| 32 | static_assert(f({1, 2}) == 12); |
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| 33 | |
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| 34 | constexpr bool g(S &&s) { |
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| 35 | auto &[a, b] = s; |
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| 36 | return &a == &s.a && &b == &s.b && &a != &b; |
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| 37 | } |
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| 38 | static_assert(g({1, 2})); |
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| 39 | |
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| 40 | void enclosing() { |
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| 41 | struct S { int a; }; |
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| 42 | auto [n] = S(); // expected-note 2{{'n' declared here}} |
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| 43 | |
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| 44 | struct Q { int f() { return n; } }; // expected-error {{reference to local binding 'n' declared in enclosing function}} |
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| 45 | // FIXME: This is probably supposed to be valid, but we do not have clear rules on how it's supposed to work. |
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| 46 | (void) [&] { return n; }; // expected-error {{reference to local binding 'n' declared in enclosing function}} |
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| 47 | (void) [n] {}; // expected-error {{'n' in capture list does not name a variable}} |
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| 48 | } |
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| 49 | |
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| 50 | void bitfield() { |
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| 51 | struct { int a : 3, : 4, b : 5; } a; |
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| 52 | auto &[x, y] = a; |
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| 53 | auto &[p, q, r] = a; // expected-error {{decomposes into 2 elements, but 3 names were provided}} |
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| 54 | } |
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| 55 | |
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| 56 | void for_range() { |
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| 57 | int x = 1; |
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| 58 | for (auto[a, b] : x) { // expected-error {{invalid range expression of type 'int'; no viable 'begin' function available}} |
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| 59 | a++; |
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| 60 | } |
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| 61 | |
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| 62 | int y[5]; |
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| 63 | for (auto[c] : y) { // expected-error {{cannot decompose non-class, non-array type 'int'}} |
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| 64 | c++; |
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| 65 | } |
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| 66 | } |
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| 67 | |
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| 68 | int error_recovery() { |
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| 69 | auto [foobar]; // expected-error {{requires an initializer}} |
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| 70 | return foobar_; // expected-error {{undeclared identifier 'foobar_'}} |
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| 71 | } |
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| 72 | |
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| 73 | // PR32172 |
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| 74 | template <class T> void dependent_foreach(T t) { |
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| 75 | for (auto [a,b,c] : t) |
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| 76 | a,b,c; |
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| 77 | } |
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| 78 | |
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| 79 | struct PR37352 { |
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| 80 | int n; |
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| 81 | void f() { static auto [a] = *this; } // expected-error {{cannot be declared 'static'}} |
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| 82 | }; |
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| 83 | |
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| 84 | namespace instantiate_template { |
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| 85 | |
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| 86 | template <typename T1, typename T2> |
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| 87 | struct pair { |
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| 88 | T1 a; |
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| 89 | T2 b; |
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| 90 | }; |
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| 91 | |
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| 92 | const pair<int, int> &f1(); |
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| 93 | |
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| 94 | int f2() { |
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| 95 | const auto &[a, b] = f1(); |
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| 96 | return a + b; |
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| 97 | } |
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| 98 | |
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| 99 | } // namespace instantiate_template |
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| 100 | |
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| 101 | // FIXME: by-value array copies |
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| 102 | |
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