Description:
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Calling the "time()" function with a parameter works fine in PHP <= 7.2.x and returns an int. In PHP 7.3, it returns NULL and produces a "Warning: time() expects exactly 0 parameters, 1 given" message instead.

https://3v4l.org/OT21N
https://github.com/php/php-src/blob/php-7.3.0/ext/date/php_date.c#L1775

I know that passing a parameter to time() is wrong, but I think it could produce a warning and return the value in PHP 7.3 (and 7.4 maybe), since it works fine in 7.2 and is common in C to call it that way. 
I did not find anything related to deprecation pages, so it may be useful to document this behavior as deprecated in case you decide to keep it as is.

Test script:
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<?php
var_dump(time(null));

Expected result:
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The current Unix timestamp.

Actual result:
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NULL