Description:
------------
Accessing a private class constant using constant() triggers an exception (as expected) and a warning.

The function should only use one way to report the inaccessible constant; prefferably the Error/Exception. Removing the warning from the constant() function would result in the same behaviour as accessing the constant directly.

A small test script is attached, a slightly larger version is linked here:

https://3v4l.org/JY1AO


Test script:
---------------
<?php

class Foo {
    private const C1 = "a";
}

try {
    var_dump(constant('Foo::C1'));
} catch(Error $e) {
    echo 'Caught';
}

Expected result:
----------------
Caught

Actual result:
--------------
Warning: constant(): Couldn't find constant Foo::C1 in ??? on line 8
Caught