function-definition: attribute-specifier-seq decl-specifier-seq declarator virt-specifier-seq function-body
function-body: ctor-initializer compound-statement function-try-block = default ; = delete ;Any informal reference to the body of a function should be interpreted as a reference to the non-terminal function-body.
static const char __func__[] = "function-name";
had been provided, where function-name is an implementation-defined string.struct S { S() : s(__func__) { } // OK const char* s; }; void f(const char* s = __func__); // error: __func__ is undeclared
attribute-specifier-seq decl-specifier-seq declarator virt-specifier-seq = default ;is called an explicitly-defaulted definition.
struct S { constexpr S() = default; // ill-formed: implicit S() is not constexpr S(int a = 0) = default; // ill-formed: default argument void operator=(const S&) = default; // ill-formed: non-matching return type ~S() noexcept(false) = default; // deleted: exception specification does not match private: int i; S(S&); // OK: private copy constructor }; S::S(S&) = default; // OK: defines copy constructor
struct trivial {
trivial() = default;
trivial(const trivial&) = default;
trivial(trivial&&) = default;
trivial& operator=(const trivial&) = default;
trivial& operator=(trivial&&) = default;
~trivial() = default;
};
struct nontrivial1 {
nontrivial1();
};
nontrivial1::nontrivial1() = default; // not first declaration
attribute-specifier-seq decl-specifier-seq declarator virt-specifier-seq = delete ;is called a deleted definition.
struct onlydouble {
onlydouble() = delete; // OK, but redundant
onlydouble(std::intmax_t) = delete;
onlydouble(double);
};
struct sometype { void* operator new(std::size_t) = delete; void* operator new[](std::size_t) = delete; }; sometype* p = new sometype; // error, deleted class operator new sometype* q = new sometype[3]; // error, deleted class operator new[]
struct moveonly {
moveonly() = default;
moveonly(const moveonly&) = delete;
moveonly(moveonly&&) = default;
moveonly& operator=(const moveonly&) = delete;
moveonly& operator=(moveonly&&) = default;
~moveonly() = default;
};
moveonly* p;
moveonly q(*p); // error, deleted copy constructor
struct sometype {
sometype();
};
sometype::sometype() = delete; // ill-formed; not first declaration