https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107343
Bug ID: 107343
Summary: GCC accepts ill-formed out of class definition program
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jlame646 at gmail dot com
Target Milestone: ---
The following ill-formed program is accepted by gcc and msvc. Demo:
https://godbolt.org/z/9PhnbYhb3
```
class complex {
public:
complex (double r, double i);
complex ();
complex(const complex &c);
complex add(complex &c);
void norm1();
private:
double re, im;
double norm;
};
//this is ill-formed as it turned it into default ctor
complex::complex(double r=0.0, double i=0.0){
re = r; im = i;
norm1();
};
complex::complex(){
re=im=0;
}
complex::complex(const complex &c){
re=c.re;
im=c.im;
}
void complex::norm1(){
norm = sqrt(re*re + im*im);
};
complex complex::add(complex &c){
return complex( re + c.re, im + c.im);
};
int main(){
complex c1(3,4), c2(1,2);
return 0;
}
```
According to https://en.cppreference.com/w/cpp/language/default_arguments
> For a member function of a non-template class, the default arguments are
> allowed on the out-of-class definition, and are combined with the default
> arguments provided by the declaration inside the class body. If these
> out-of-class defaults would turn a member function into a default constructor
> or copy/move (since C++11) constructor/assignment operator, the program is
> ill-formed.
