Implement GH-11934: Allow to pass CData into struct and/or union fields

[nielsdos]

Implementation based on a discussion with KapitanOczywisty.

[KapitanOczywisty]

This function changed quite a few things, so more tests could be added. I don't know what is the windows equivalent for the last one, and likely it is not the best test either.

I've tested all of them in 8.2 (fail) and 8.3 (success).

Tests

<?php

echo "--- Callback return type --- \n";

$ffi = FFI::cdef('
typedef uint32_t (*test_callback)();
typedef struct {
	test_callback call_me;
} my_struct;
');

$struct = $ffi->new('my_struct');
$struct->call_me = function () use ($ffi) {
	$int = $ffi->new('uint32_t');
	$int->cdata = 42;
	return $int;
};

var_dump(($struct->call_me)());

echo "--- Other FFI\CData assignment ---\n";

$ffi = FFI::cdef('');

$source = $ffi->new('uint32_t');
$source->cdata = 123;
$target = $ffi->new('uint32_t');
$target->cdata = $source;

var_dump($target->cdata);

echo "--- Array element ---\n";

$ffi = FFI::cdef('');

$source = $ffi->new('uint32_t');
$source->cdata = 123;
$target = $ffi->new('uint32_t[1]');
$target[0] = $source;

var_dump($target[0]);

echo "--- Existing C variables --- \n";

$ffi = FFI::cdef(
	"int errno;",
	"libc.so.6"
);
$ffi->errno = 0;
var_dump($ffi->errno);
$source = $ffi->new('int');
$source->cdata = 31;
$ffi->errno = $source;
var_dump($ffi->errno);

[bukka]

Seem like small sefl contained change so if you manage to get approval from @dstogov (maintainer) before the first RC, I would be fine with this going to 8.3.

[nielsdos]

@KapitanOczywisty Good call, in particular the subtle difference of the callback is clearly a candidate for testing. I've added all your tests in an additional commit, with your co-authored-by tag to credit you.

[KapitanOczywisty]

@nielsdos I found in other ffi tests how to do C variable test properly: KapitanOczywisty@f3d6246

And callback test is duplicated on purpose?

[nielsdos]

@nielsdos I found in other ffi tests how to do C variable test properly: KapitanOczywisty@f3d6246

Neat, I've added your commit, thanks.

And callback test is duplicated on purpose?

No, sorry for the mess. I was experimenting with creating a variation earlier and didn't fully undo my changes.

[dstogov]

Merge this into PHP-8.3.