[Xapian-tickets] [Xapian] #817: Add PHP 8 support

[Xapian]

#817: Add PHP 8 support
-----------------------------------+---------------------------
 Reporter:  Ryan Schmidt           |             Owner:  (none)
     Type:  enhancement            |            Status:  new
 Priority:  normal                 |         Milestone:
Component:  Xapian-bindings (PHP)  |           Version:  1.4.19
 Severity:  normal                 |        Resolution:
 Keywords:                         |        Blocked By:
 Blocking:                         |  Operating System:  All
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Comment (by Olly Betts):

 That error was new in 1.4.19, but in 1.4.18 you'd have got an obscure
 compile error with PHP8 instead:

 ```
 error: cannot initialize a parameter of type 'zend_object *' (aka
 '_zend_object *') with an lvalue of type 'zval *' (aka '_zval_struct *')
 ```

 This is because PHP's C API has changed a bit in PHP8.  We need SWIG to
 add support PHP8 - the current status is SWIG git master supports PHP8 but
 this is not in a stable SWIG release yet.

 However there have been major changes in how SWIG-generated PHP wrappers
 work - instead of the generated .php script with class definitions,
 classes are created from C/C++ code using PHP's C API.  These changes are
 definitely for the better as they fix a lot of problems with the old
 approach and the new generated bindings should also be faster.  However it
 does mean updating our bindings is going to require more work than just
 using a new SWIG version since currently we post-process the generated
 wrapper script to add type declarations to function parameters and keep
 references to set objects.

 When https://github.com/swig/swig/issues/2027 is merged that will
 automatically add type declarations for PHP8.  I'm not sure what to do for
 PHP7 though - the type declaration API is very different there (it had to
 be reworked to allow PHP8 to support things like `int|object`).  Perhaps
 we just leave the PHP7 bindings as-is (and drop them in the next release
 series - PHP7.4's EOL is only ~10 months away now).  The awkward part is
 that probably means we would need two different SWIG versions to generate
 bindings for PHP7 and PHP8.  Maybe we can post-process the generated C++
 wrapper code to add them.  Or perhaps just drop PHP7 support in the 1.4.x
 release that adds PHP8 support and tell people who still want PHP7 support
 to use the last 1.4.x xapian-bindings which had support.

 I'm hoping we can deal with keeping references to set objects using custom
 typemaps or maybe `%extend` but I've not tried yet.

 Also https://github.com/swig/swig/issues/2125 really needs fixing.

 So PHP8 support is coming, but it may be a while away yet I'm afraid.
-- 
Ticket URL: <https://trac.xapian.org/ticket/817#comment:1>
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