No zero_t constructor for int

[a3moss]

int doesn't satisfy assertions like void ?{} ( T&, zero_t ); and probably should.

The Parametric Polymorphism example on the website doesn't compile as written. The workaround for this in the rational.cfa test is to define the following three user-generated constructors, but this is a hack in place since mid-2017:

void ?{}( int & this ) { this = 0; }
void ?{}( int & this, zero_t ) { this = 0; }
void ?{}( int & this, one_t ) { this = 1; }

[Thierry Delisle]

Int now satisfy the mentioned assertion.