[PHP-INTERNALS] Add E_STRICT when defining a required function parameter after an optional parameter

Given the semantics of PHP arguments, there is "nothing wrong" with
defining a required argument after an optional one, and in some cases
it is required. Consider:

function foo(Plop $a, $b) {}

if you want to allow 'null' for $a as well, you have to write:

function foo(Plop $a = null, $b) {}

Best,

Hi!
I think there's something wrong with it, primarily - the fact that it
doesn't really make any sense. The object/null thing is a kludge.
Unfortunately, I don't see a proper way to handle this without named
arguments.

Ok, I re-wrote the patch and test:
http://bugs.php.net/patch-display.php?bug_id=53399&patch=strict-required-opt2.patch&revision=latest

Now, the test happens in zend_do_end_function_declaration(). It loops through each of the function's parameters and emits the E_STRICT if it detects a required parameter after an optional parameter. The tests are loosened so that Class $param = null will not by itself trigger the warning. So it's not a 100% solution since we have to allow for the object/null kludge, but it's still an improvement from not having anything at all.

To make this work, I added a field to zend_arg_info, 'optional', which is populated in zend_do_receive_arg(). Also, we might want to modify php_reflection.c:_parameter_string() to use zend_arg_info.optional, which would allow indicating whether the parameter was declared optional vs. whether it actually is being treated as optional.

I think I can move the implementation back into zend_do_receive_arg(), but before I go ahead and do that, I'd like to make sure everyone's happier with this solution than my first. It might also be possible to get rid of zend_arg_info.optional, but I'd need to know how/if it's possible to access the relevant oplines for the rest of the function's parameters.

-John

Sure, it's hackish as hell, but that's PHP's fault, not the user using
it.

My point is that we shouldn't add new E_STRICTs for something with no
possible alternatives.