ZDoom

That's correct.

Made [url=https://github.com/coelckers/gzdoom/pull/705]this PR[/url] to be sure I got it right. As expected with this change generated code remains the same.

The problem is that the Resolve function does not properly promote the type if the operand is bool.

class UnaryMinusBool : Actor
{
	states
	{
	spawn:
		TNT1 A 1
		{
			bool a = false;
			int i = -a;
			
			bool b = true;
			int j = -b;
			
			console.printf("%i %i", i, j);
		}
	}
}

Loading the following ZScript will trigger an assertion failure [url=https://github.com/coelckers/gzdoom/blob/cf967b36ffe0abb3da6da99a408a76c4d2d88373/src/scripting/backend/codegen.cpp#L1903]here[/url]: [b]ValueType[/b] is "Int" while [b]Operand->ValueType[/b] is "Bool".

[code]class UnaryMinusBool : Actor
{
states
{
spawn:
TNT1 A 1
{
bool a = false;
int i = -a;

bool b = true;
int j = -b;

console.printf("%i %i", i, j);
}
}
}[/code]
Generated code seems to be correct. The sample outputs expected values, 0 and -1.
I suspect the assertion's condition is too strict and doesn't take bool-to-int type propagation into account.