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// RUN: %clang_cc1 -std=c++1z -verify %s
void use_from_own_init() {
auto [a] = a; // expected-error {{binding 'a' cannot appear in the initializer of its own decomposition declaration}}
}
// As a Clang extension, _Complex can be decomposed.
float decompose_complex(_Complex float cf) {
static _Complex float scf;
auto &[sre, sim] = scf;
// ok, this is references initialized by constant expressions all the way down
static_assert(&sre == &__real scf);
static_assert(&sim == &__imag scf);
auto [re, im] = cf;
return re*re + im*im;
}
// As a Clang extension, vector types can be decomposed.
typedef float vf3 __attribute__((ext_vector_type(3)));
float decompose_vector(vf3 v) {
auto [x, y, z] = v;
auto *p = &x; // expected-error {{address of vector element requested}}
return x + y + z;
}
struct S { int a, b; };
constexpr int f(S s) {
auto &[a, b] = s;
return a * 10 + b;
}
static_assert(f({1, 2}) == 12);
constexpr bool g(S &&s) {
auto &[a, b] = s;
return &a == &s.a && &b == &s.b && &a != &b;
}
static_assert(g({1, 2}));
void enclosing() {
struct S { int a; };
auto [n] = S(); // expected-note 2{{'n' declared here}}
struct Q { int f() { return n; } }; // expected-error {{reference to local binding 'n' declared in enclosing function}}
// FIXME: This is probably supposed to be valid, but we do not have clear rules on how it's supposed to work.
(void) [&] { return n; }; // expected-error {{reference to local binding 'n' declared in enclosing function}}
(void) [n] {}; // expected-error {{'n' in capture list does not name a variable}}
}
void bitfield() {
struct { int a : 3, : 4, b : 5; } a;
auto &[x, y] = a;
auto &[p, q, r] = a; // expected-error {{decomposes into 2 elements, but 3 names were provided}}
}
// FIXME: by-value array copies
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