Please try:

    <?php
    final class MyClass { function mymethod() {} };
    var_dump( ( new ReflectionClass( 'MyClass') )->isFinal() );
    uopz_flags(MyClass::class, null, 0);
    var_dump( ( new ReflectionClass( 'MyClass') )->isFinal() );

This should print:

    bool(true)
    bool(false)

Result:

PHP Fatal error:  Uncaught InvalidArgumentException: 
unexpected parameter combination, 
expected (class, function, flags) or (function, flags)
Stack trace: #0: uopz_flags('MyClass', NULL, 0)

Thanks for testing.  However, my test script works for me on
Windows with PHP 5.6 with UOPZ 2.0.7 and PHP 7.1 and 7.2 with UOPZ
5.0.2, which is to be expected from looking at the relevant
code[1].

The InvalidArgumentException would be thrown, though, if an yet
undefined class would be passed as first parameter to
uopz_flags().  Is there perhaps an issue with OPcache?  Note that
UOPZ should be loaded before OPcache.

[1] <https://github.com/krakjoe/uopz/blob/v5.0.2/uopz.c#L530>

No Opcode active. I even disabled WinCache and xdebug extensions and retestet. In addition, I moved the uopz extension to be first one .ini file.

Result remains:
PHP Fatal error:  Uncaught InvalidArgumentException: unexpected parameter combination, expected (class, function, flags) or (function, flags) 
Stack trace:
#0 E:\Hosted Sites\wwwroot\anamera_v2\test\syntax.php(6): uopz_flags('MyClass', NULL, 0)
#1 {main}

To me, the message does NOT indicate that "class" does not exist, it seems to state that the parameter signature doesn't match one of the two permitted variations.

This is further supported by the fact that THIS will work just fine:

var_dump( uopz_flags(MyClass::class, 'mymethod', 0) );

If the problem was an absent MyClass, then the combination MyClass::mymethod would also have failed.

So - as long as a method parameter is not left NULL, the uopz_flags function will work as expected.

In fact, lookin at YOUR code snippet you sent me, it does seem to permit either an object or string for the FIRST parameter (scope), and ONLY a string for the SECOND parameter (prop)? If the second parameter is NOT a string, then the error message will be logged to the php error log:

!scope || !prop || !value ||
(Z_TYPE_P(scope) != IS_OBJECT && Z_TYPE_P(scope) != IS_STRING) ||
Z_TYPE_P(prop) != IS_STRING)

I was assuming "normal" typing, not strict typing.  In the latter
case passing NULL as second argument to uopz_flags() would indeed
trigger an InvalidArgumentException.

Joe, could you please clarify whether retrieving and changing
attributes of a class via uopz_flags() is supposed to work by
passing an empty string as second argument?

Fixed with <http://svn.php.net/viewvc?view=revision&revision=350311>.