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// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11
// Implicitly-defined default constructors are constexpr if the implicit
// definition would be.
struct NonConstexpr1 { // expected-note {{here}}
int a;
};
struct NonConstexpr2 { // expected-note {{here}}
NonConstexpr1 nl;
};
struct NonConstexpr2a : NonConstexpr1 { };
constexpr NonConstexpr1 nc1 = NonConstexpr1(); // ok, does not call constructor
constexpr NonConstexpr2 nc2 = NonConstexpr2(); // ok, does not call constructor
constexpr NonConstexpr2a nc2a = NonConstexpr2a(); // ok, does not call constructor
constexpr int nc2_a = NonConstexpr2().nl.a; // ok
constexpr int nc2a_a = NonConstexpr2a().a; // ok
struct Helper {
friend constexpr NonConstexpr1::NonConstexpr1(); // expected-error {{follows non-constexpr declaration}}
friend constexpr NonConstexpr2::NonConstexpr2(); // expected-error {{follows non-constexpr declaration}}
};
struct Constexpr1 {};
constexpr Constexpr1 c1 = Constexpr1(); // ok
struct NonConstexpr3 : virtual Constexpr1 {}; // expected-note {{struct with virtual base}} expected-note {{declared here}}
constexpr NonConstexpr3 nc3 = NonConstexpr3(); // expected-error {{non-literal type 'const NonConstexpr3'}}
struct Constexpr2 {
int a = 0;
};
constexpr Constexpr2 c2 = Constexpr2(); // ok
int n;
struct Member {
Member() : a(n) {}
constexpr Member(int&a) : a(a) {}
int &a;
};
struct NonConstexpr4 { // expected-note {{here}}
Member m;
};
constexpr NonConstexpr4 nc4 = NonConstexpr4(); // expected-error {{constant expression}} expected-note {{non-constexpr constructor 'NonConstexpr4'}}
struct Constexpr3 {
constexpr Constexpr3() : m(n) {}
Member m;
};
constexpr Constexpr3 c3 = Constexpr3(); // ok
struct Constexpr4 {
Constexpr3 m;
};
constexpr Constexpr4 c4 = Constexpr4(); // ok
// This rule breaks some legal C++98 programs!
struct A {}; // expected-note {{here}}
struct B {
friend A::A(); // expected-error {{non-constexpr declaration of 'A' follows constexpr declaration}}
};
namespace UnionCtors {
union A { // expected-note {{here}}
int a;
int b;
};
union B {
int a;
int b = 5;
};
union C {
int a = 5;
int b;
};
struct D {
union {
int a = 5;
int b;
};
union {
int c;
int d = 5;
};
};
struct E { // expected-note {{here}}
union {
int a;
int b;
};
};
struct Test {
friend constexpr A::A() noexcept; // expected-error {{follows non-constexpr declaration}}
friend constexpr B::B() noexcept;
friend constexpr C::C() noexcept;
friend constexpr D::D() noexcept;
friend constexpr E::E() noexcept; // expected-error {{follows non-constexpr declaration}}
};
}
namespace PR48763 {
// FIXME: We implement a speculative wording fix here: if a class inherits a
// default constructor and doesn't declare one itself, we declare an default
// constructor implicitly. This allows us to meanignfully reason about
// whether that default constructor is constexpr, trivial, and so on.
struct A { constexpr A() {} };
struct B : A {
using A::A;
constexpr B(int) {}
};
struct C { B b; };
constexpr C c;
struct D { int n; };
struct E : D { using D::D; E(int); };
static_assert(E().n == 0, "");
static_assert(E{}.n == 0, "");
struct F { E e; };
static_assert(F().e.n == 0, "");
static_assert(F{}.e.n == 0, "");
union U { E e; };
U u; // OK, trivial default constructor
struct G { G(); };
struct H : D { using D::D; H(int); G g; };
union V { H h; }; // expected-note {{field 'h' has a non-trivial default constructor}}
V v; // expected-error {{deleted}}
}
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