Per-translation-unit variable indexing

[ForNeVeR]

Originally posted by @ForNeVeR in #617 (comment)

Currently, we have a global static counter, CurrentIndex in the Cesium.CodeGen.Contexts.VariableInfo record.

Cesium/Cesium.CodeGen/Contexts/VariableInfo.cs

Lines 7 to 11 in f1b5204

	internal record VariableInfo(StorageClass StorageClass, IType Type, IExpression? Constant)
	{
	static int CurrentIndex = 0;
	public int Index { get; } = checked(CurrentIndex++);
	}

I'd like to have some sort of indexing that's tied to the translation unit.

Such a counter is too error-prone: it will easily overflow on 2 billion variables constructed in a single compilation session. Moreover, this construct makes it impossible to copy a VariableInfo.

[kant2002]

I think if put CurrentIndex into FunctionScope that would work.

[ForNeVeR]

Yep, most likely it will.