CODEWITHSUNDEEP
c++c++11
user1095108
user1095108

Reputation: 14603

can defaulted default constructors throw?

Defaulted default constructors are generated by the C++ compiler, the user has no control over them. Can they throw? Is it ok to specify noexcept when declaring one?

The following code compiles fine with gcc.

struct A
{
  A() = default;
};

struct B
{
  B() noexcept = default;
};

int main()
{
  A a;
  B b;

  return 0;
}

Upvotes: 6

Views: 479

Answers (2)

pmr
pmr

Reputation: 59831

It is allowed to add a noexcept specifier to a defaulted special member function (default constructor, copy-constructor, assignment-operator etc.).

A default declared special member function will have a noexcept specifier depending on the noexcept specifiers of the involved functions (its implicit noexcept specifier). If you explicitly specify noexcept compilation should fail if this conflicts with the implicit noexcept specifier.

Upvotes: 8

juanchopanza
juanchopanza

Reputation: 227468

can default constructors throw?

Yes, they can. For example, if the class has data member(s) whose default constructor throws.

struct Foo
{
  Foo() { /* throws */} 
};

struct Bar
{
  Bar() = default;
  Foo f;
}

Upvotes: 5

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