Incorrect type variables in some SMethodDesc instances

[kettlebell]

Found while expanding scala JIT test suite examples for issue #633.

E.g. consider the Coll.zip method.

In scala the implementation is here: https://github.com/ScorexFoundation/sigmastate-interpreter/blob/0c5c5b515ccb452536e440469b56d763d5ba30ec/sigmastate/src/main/scala/sigmastate/types.scala#L1658

Note the use of the IV and OV type variables.

Now on rust the T type variable is used:

sigma-rust/ergotree-ir/src/types/scoll.rs

Lines 84 to 89 in 7f44ece

	static ref ZIP_METHOD_DESC: SMethodDesc = SMethodDesc {
	method_id: ZIP_METHOD_ID,
	name: "zip",
	tpe: SFunc::new(
	vec![
	SType::SColl(SType::STypeVar(STypeVar::t()).into()),

This breaks my proc-macro test which is directly lifted from Scala:

#[test]
fn test_method_call_zip_0() {
    // { (x: Coll[Box]) => x.zip(x) }
    let _ = ergo_tree!(
        FuncValue(
            Vector((1, SCollectionType(SBox))),
            MethodCall.typed[Value[SCollection[STuple]]](
              ValUse(1, SCollectionType(SBox)),
              SCollection.getMethodByName("zip").withConcreteTypes(
                Map(STypeVar("IV") -> SBox, STypeVar("OV") -> SBox)
              ),
              Vector(ValUse(1, SCollectionType(SBox))),
              Map()
            )
        )
    );
}

This gives test gives the following error:

thread 'test_method_call_zip_0' panicked at 'called `Result::unwrap()` on an `Err` value: InvalidArgumentError("MethodCall: expected types [SColl(STypeVar(\"T\")), SColl(SBox)] do not match provided obj and args types [SColl(SBox), SColl(SBox)]")'

There are others with similar problems like Coll.patch.

[greenhat]

Good catch! I was probably writing them without putting too many thoughts into keeping type var names in sync with Scala.

[kettlebell]

I'll take care of cleaning this up!

[greenhat]

Thank you!