to silence compile warnings on some compilers/platforms

Okay, didn't know about this. Will do.

Took a quick look, for GCC I could see:

https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmissing-field-initializers

-Wmissing-field-initializers

Warn if a structure’s initializer has some fields missing. For example, the following code causes such a warning, because x.h is implicitly zero:

struct s { int f, g, h; };
struct s x = { 3, 4 };

In C this option does not warn about designated initializers, so the following modification does not trigger a warning:

struct s { int f, g, h; };
struct s x = { .f = 3, .g = 4 };

In other words, this warning doesn't apply here. The same goes for Clang. I couldn't find an equivalent option for MSVC at all. I also found a few existing examples in php-src where not all fields are being set, indicating this is probably not an issue.

Thanks for checking, LGTM then!