Besidesfunction-call expressions, whereoverload resolution takes place, the name of an overloaded function may appear in the following 7 contexts:

In each context, the name of an overloaded function may be preceded by address-of operator& and may be enclosed in a redundant set of parentheses.

[edit]Selecting functions

When the address of an overloaded function is taken, a setS of functions is selected from the overload set referred to by the name of the overload function:

• If there is no target, all non-template functions named are selected.
• Otherwise, a non-template function with typeF is selected for the function typeFT of the target type ifF (after possibly applying thefunction pointer conversion)(since C++17) is identical toFT.^[1]
• The specialization (if any) generated bytemplate argument deduction for each function template named is also added toS.

If the target is of function pointer type or reference to function type,S can only include non-member functions, explicit object member functions(since C++23) and static member functions. If the target is of pointer-to-member-function type,S can only include implicit object member functions.

1. ↑In other words, the class of which the function is a member is ignored if the target type is a pointer-to-member-function type.

[edit]Eliminating functions

After forming the setS, functions are elimiated in the following order:

• If more than one function inS remains, all function template specializations inS are eliminated ifS also contains a non-template function.

• Any given function template specializationspec is eliminated ifS contains a second function template specialization whose function template ismore specialized than the function template ofspec.

After such eliminations (if any), exactly one selected function should remain inS. Otherwise, the program is ill-formed.

[edit]Example

int f(int){return1;}int f(double){return2;} void g(int(&f1)(int),int(*f2)(double)){ f1(0); f2(0.0);} template<int(*F)(int)>struct Templ{}; struct Foo{int mf(int){return3;}int mf(double){return4;}}; struct Emp{void operator<<(int(*)(double)){}}; int main(){// 1. initializationint(*pf)(double)= f;// selects int f(double)int(&rf)(int)= f;// selects int f(int)int(Foo::*mpf)(int)=&Foo::mf;// selects int mf(int) // 2. assignment    pf= nullptr;    pf=&f;// selects int f(double) // 3. function argument    g(f, f);// selects int f(int) for the 1st argument// and int f(double) for the second // 4. user-defined operator    Emp{}<< f;//selects int f(double) // 5. return valueauto foo=[]()->int(*)(int){return f;// selects int f(int)}; // 6. castauto p=static_cast<int(*)(int)>(f);// selects int f(int) // 7. template argument    Templ<f> t;// selects int f(int) // prevent “unused variable” warnings as if by [[maybe_unused]][](...){}(pf, rf, mpf, foo, p, t);}

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]References

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