ext/standard: make debug_zval_dump() output whether the array is packed

[MaxSem]

Packed arrays can make a lot of difference, however lots of developers simply don't
know about them or when an array can be packed. Thus I propose to make this
information available to userspace, but as a debug tool, not something like array_is_list().

[staabm]

Is there documentation somewhere when arrays are packed/not packed and when/which/how much impact it has?

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edit: after some research I found

• https://blog.blackfire.io/php-7-performance-improvements-packed-arrays.html
• https://wiki.php.net/rfc/is_list

is this still accurate?

[MaxSem]

exposing the internal term

It's literally the purpose of this function. Quoting the manual:

Dumps a string representation of an internal zval (Zend value) structure to output. This is mostly useful for understanding or debugging implementation details of the Zend Engine or PHP extensions.

[MaxSem]

Changed "packed array" to "array packed" to be consistent with other attributes.

[staabm]

Just as an idea which could be also used in regular var_dump()

Suggested change

	array(7) packed refcount(2){
	list(7) refcount(2){

[MaxSem]

I had thought about something like this, but decided that it would be confusing because the type remains IS_ARRAY at all times.

[jorgsowa]

It's literally the purpose of this function. Quoting the manual

Sorry. Confused it with var_dump(). Then, it's completely fine.

[Girgias]

Makes sense to me, can you add an entry to UPGRADING/NEWS ?

[MaxSem]

Makes sense to me, can you add an entry to UPGRADING/NEWS ?

Done.

[Girgias]

Thank you!