Zend: fix gcc12 -Warray-bounds warning

[crrodriguez]

gcc12 complains:

zend_API.c:2782:49: warning: array subscript ‘zend_function {aka union _zend_function}[0]’ is partly outside array bounds of ‘unsigned char[120]’ [-Warray-bounds]
zend_API.c:2772:32: note: object of size 120 allocated by ‘malloc’
reg_function = malloc(sizeof(zend_internal_function));

The warning is correct, reg_function allocation size is too small for its type,
allocate sizeof(zend_function) instead.

[cmb69]

Ah yeah, this looks right, thank you! Shouldn't this be fixed for PHP-8.0+, though?

[cmb69]

That calloc() appears unnecessary, since we're overwriting the memory in the next statement anyway.

[bwoebi]

@cmb69 the allocation has the right size, but technically the proper target is &reg_function->internal_function to assign to instead of reg_function. (we're allocating an internal function, not an op_array)
(i.e. it's "just" a compiler warning, which does not have a deep view into that union and does not know that reg_function->op_array is not allowed)

[cmb69]

Holy hack, Batman! I see that this is not a bug in php-src.

But if we always treat reg_function as internal function, why not declare and use it as such?

[bwoebi]

I suppose to avoid a couple explicit casts back to zend_function * when passing reg_function around to some calls?

[cmb69]

According to the discussion so far, this doesn't look like the proper fix. Either there is a simple way to avoid the compiler warning, or maybe we should see how changing reg_function to be of type zend_internal_function may work out.

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