c++ - Inheriting constructors w / wo their default arguments? -

c++ primer (5th edition) on page 629 states:

• if base class constructor has default arguments, arguments not inherited.

i tried myself , me seems derived constructor generated compiler has same default arguments base constructor.

here's little test:

#include <iostream>  struct base {     base() = default;      base(int x_, int y_ = 88, int z_ = 99)         : x(x_), y(y_), z(z_) {}      virtual void debug() const      { std::cout << "\nx - " << x << ", y - " << y << ", z - " << z << '\n'; }   private:     int x, y, z; };  struct derived : base {     using base::base; };  int main() {     base b(1);     b.debug();         // x - 1, y - 88, z - 99     derived d(5);     d.debug();         // x - 5, y - 88, z - 99      return 0; } 

( can run here - http://coliru.stacked-crooked.com/a/26cbb85757c1f021 )

so inheriting default arguments inherited constructor or not?
if not, how come i'm not getting junk last 2 members same exact values default argumuments constructor inherited base?
searched on internet clear response found none.

from [class.inhctor]:

the candidate set of inherited constructors class x named in using-declaration consists of actual constructors , notional constructors result transformation of defaulted parameters , ellipsis parameter specifications follows:
— [...]
— each non-template constructor of x has @ least 1 parameter default argument, set of constructors results omitting ellipsis parameter specification , successively omitting parameters default argument end of parameter-type-list, and
— [...]

we have 2 non-template constructors of base. default constructor of base introduces candidate:

derived() : base() { } 

and other constructor of base introduces 1 candidate each successively omitted parameter. namely:

derived(int x, int y, int z) : base(x, y, z) { } derived(int x, int y)        : base(x, y) { } derived(int x)               : base(x) { } 

the default arguments not inherited - different constructor each number of arguments. derived(5) calls base(5), not base(5, 88, 99).

the end result same - how there bit different.