[CoM/LeGo] support for reinterpret_cast in scripts

[Try]

Here some code example to illustrate:

func void FADEOUTFINISH() {
	var OCNPC HER;  <---- OCNPC!
	if (FF_ACTIVE(FADESCREENTOBLACKLOOP)) {
		FF_REMOVE(FADESCREENTOBLACKLOOP);
	};
	FADESCREENSTATE = 0;
	SCREENFADED = TRUE;
	if (FADESCREENWORLDCHANGE) {
		HER = HLP_GETNPC(HERO); <----- implicit cast!
		HER.BITFIELD[0] = HER.BITFIELD[0] & ~OCNPC_BITFIELD0_MOVLOCK;
		....
		FADESCREENCHANGEWORLD();
	};
};

or

func void TELEPORTHEROTOPOS(var int X, var int Y, var int Z) {
	var OCNPC HER;
	HER = HLP_GETNPC(HERO);
	HER._ZCVOB_TRAFOOBJTOWORLD[3] = X;
	HER._ZCVOB_TRAFOOBJTOWORLD[7] = Y;
	HER._ZCVOB_TRAFOOBJTOWORLD[11] = Z;
};

Keeping discussion open for now; however my current idea is to:

• implement type-check for 'default' VM mode - it should throw exception, if C_Npc is assigned to OCNPC or any other non-compatible type.
• have 'special' mode, when instead of exception callback is called. It's reproducibility of callback to handle conversion. In those examples fro npc to zenkit::DaedalusTransientInstance and vise-versa.

[lmichaelis]

Hm, you say this is an implicit cast, but what kind of cast is it? Assuming it's a reinterpret_cast<oNpc*> then it might be nicer to provide a set of casting rules instead (if that's all you need).

I'm envisioning a sort of vm.register_cast<A, B>(), HOWEVER if I remember correctly, the original Daedalus compiler does not always store the type of the instance (e.g. when passed as function parameters iirc), so neither solution would work properly. In that case, replacing the default instance implementations provided by ZenKit with custom transient ones would be required (any maybe even faster?)

[Try]

Assuming it's a reinterpret_cast<oNpc*> then it might be nicer to provide a set of casting rules instead (if that's all you need).

I'll do some prototyping first; however rules are unlikely help much. In example above C_Npc is "normal" class with no defined memory layout. We also can't really define any reasonable layout because of strings: std::string wont match across builds and x64 wont match with x86.

I'm envisioning a sort of vm.register_cast<A, B>(), HOWEVER if I remember correctly, the original Daedalus compiler..

My idea was similar, but without templates, with ret-codes rather. We may have null type-id in VM for zenkit::DaedalusTransientInstance - those are fine, they are handled by x86 emulation layer in OpenGothic and byte-compatible in a way that Ikarus/CoM expects.