Allow null variables to be decremented

Hi all, There is currently an odd inconsistency when using the decrement operator on a null variable: $a = null; $a=$a+1; // int(1) $a = null; $a+=1; // int(1) $a = null; ++$a; // int(1) $a = null; $a=$a-1; // int(-1) $a = null; $a-=1; // int(-1) $a = null; --$a; // null I would like to propose changing this behaviour for PHP 8, so that --$a would give int(-1), as I believe it is simply a long-standing bug. This has been raised as a bug at least three times [1][2][3] but closed as documented behaviour / too much of a BC break. It is documented in the manual, but with no explanation of why it should work that way. [4] I would be interested in any explanations of why it might be intended behaviour, or ways in which people might be relying on the current behaviour. A proposal to change the behaviour was included in a wider RFC about standardising increment and decrement behaviour, but it never got beyond draft status. [5] I would prefer not to reopen that wider debate, but focus on this single issue. As far as I can see, the change would be to add a "case IS_NULL" branch to decrement_function in zend_operators.c to match the one in increment_function. [6] I will happily write up an RFC to formalise this, but wanted to gather people's immediate thoughts first. Links: [1] https://bugs.php.net/bug.php?id=20548 [2] https://bugs.php.net/bug.php?id=25674 [3] https://bugs.php.net/bug.php?id=41690 [4] https://www.php.net/manual/en/language.operators.increment.php [5] https://wiki.php.net/rfc/normalize_inc_dec [6] https://php-lxr.adamharvey.name/source/xref/master/Zend/zend_operators.c#2359 Regards, -- Rowan Tommins (né Collins) [IMSoP]