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// P0963R3 - Structured binding declaration as a condition
// { dg-do compile { target c++11 } }
// { dg-options "" }
int a[4];
struct S { int i, j; };
struct T { int i, j, k; explicit operator bool () const noexcept; } t;
enum E { E0, E1 };
struct U { int i, j, k, l; operator E () const noexcept; } u;
int w;
union X { int i; long j; } x;
void
foo (const S &&s)
{
if (auto [ i, j, k, l ] = a) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "array initializer for structured binding declaration in condition" "" { target *-*-* } .-1 }
if (auto & [a, b, c] = "ht") // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "array initializer for structured binding declaration in condition" "" { target *-*-* } .-1 }
if (auto const & [i, j] = s) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "could not convert '<structured bindings>' from 'const S' to 'bool'" "" { target *-*-* } .-1 }
if (auto const & [i, j, k] = t) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
w = i + j + k;
else
w = i - j * k;
if (auto [i, j, k, l] = u) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
;
if (auto [i] = x) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "cannot decompose union type 'X'" "" { target *-*-* } .-1 }
// { dg-error "could not convert '<structured bindings>' from 'X' to 'bool'" "" { target *-*-* } .-2 }
if (auto [i, j, k] = s) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "3 names provided for structured binding" "" { target *-*-* } .-1 }
// { dg-error "could not convert '<structured bindings>' from 'S' to 'bool'" "" { target *-*-* } .-2 }
if (auto [i] = s) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "only 1 name provided for structured binding" "" { target *-*-* } .-1 }
// { dg-error "could not convert '<structured bindings>' from 'S' to 'bool'" "" { target *-*-* } .-2 }
switch (auto [a, b, c] = "ht") // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
{ // { dg-error "array initializer for structured binding declaration in condition" "" { target *-*-* } .-1 }
default: // { dg-error "switch quantity not an integer" "" { target *-*-* } .-2 }
break;
}
switch (auto const & [i, j] = s) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
{ // { dg-error "switch quantity not an integer" "" { target *-*-* } .-1 }
case 1:
default:
break;
}
switch (auto const & [i, j, k] = t) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
{ // { dg-error "switch quantity not an integer" "" { target *-*-* } .-1 }
case 1:
default:
break;
}
switch (auto [i, j, k, l] = u) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
{
case E0:
++i; ++j;
break;
default:
++k; ++l;
break;
}
if (static auto [i, j, k] = t) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "'static' invalid in condition" "" { target *-*-* } .-1 }
// { dg-warning "structured binding declaration can be 'static' only in" "" { target c++17_down } .-2 }
if (constexpr auto [i, j, k] = t) // { dg-warning "structured bindings in conditions only available with" "" { target c++23_down } }
; // { dg-error "structured binding declaration cannot be 'constexpr'" "" { target *-*-* } .-1 }
}
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