Description:
------------
---
From manual page: http://www.php.net/function.gmmktime
---
The documentation of mktime() says for the return value "mktime() returns the Unix timestamp of the arguments given. If the arguments are invalid, the function returns FALSE (before PHP 5.1 it returned -1)."

However, gmmktime() only ever returns an integer as of documentation.

I checked the PHP source code.

https://github.com/php/php-src/blob/c2ef8a9acc7977d07a9a92b07352cdefa7c4b9a5/ext/date/php_date.c#L1572

mktime() and gmmktime() both use the same internal function php_mktime().

https://github.com/php/php-src/blob/c2ef8a9acc7977d07a9a92b07352cdefa7c4b9a5/ext/date/php_date.c#L1491

This one in all cases returns false on invalid parameters.

The only way for gmmktime()/php_mktime() to fail is in timelib_date_to_int():

https://github.com/php/php-src/blob/f179852f838c1d88cb39097b9557b7d2ba8e5755/ext/date/lib/timelib.c#L186

However, I do not properly understand the difference between timelib_long and timelib_sll:

https://github.com/php/php-src/blob/f179852f838c1d88cb39097b9557b7d2ba8e5755/ext/date/lib/timelib_structs.h#L144

So, when actually can gmmktime() fail in case the arguments are correct or, does it return any errors?

Test script:
---------------
http://3v4l.org/2esJM

<?php
var_dump(PHP_INT_MAX);
var_dump(gmmktime(0,0,0,1,1,PHP_INT_MAX));
?>

Expected result:
----------------
I wish:

- The function should return an error in case of integer overflows or underflows (proleptic Gregorian calender is assumed).

Issues, depending on classification of documentation bug or implementation bug:

- mktime() and gmmktime() should return the same "kind of data". So only integer, or integer or false.
- Documentation of return value of mktime() and gmmktime() should be the same.
- Documentation should mention that errors are/are not detected, so either the returned timestamp is "random" (single or multiple overflows) or an error is indicated.

Actual result:
--------------
Output for 5.2.6 - 5.6.9, php7@20140507 - 20150501
    int(9223372036854775807)
    int(-62198793216) 

Output for 5.1.3 - 5.2.5
    int(9223372036854775807)
    bool(false) 

Output for 5.1.0 - 5.1.2
    int(9223372036854775807)
    Process exited with code 137.

Output for 4.4.0 - 4.4.9, 5.0.5
    int(9223372036854775807)
    int(-62198755200)