Case 1
```
<?php
interface AI {
    const FOO = 'a';
}

class A implements AI {
    const FOO = 'Class A';
}

function test(AI $obj)
{
    echo $obj::FOO;
}

$obj = new A();
test($b);
```

Result:
`Fatal error: Cannot inherit previously-inherited or override constant FOO from interface AI in [...][...] on line 6`

Case 2
```
<?php
interface AI {
    const FOO = 'Interface';
}
class A implements AI {}
class B extends A {
    const FOO = 'Class B';
}

function test(AI $var)
{
    echo $var::FOO;
}

$obj = new B();
test($obj);
```
Result:
`Class B`