Strange compile error when combining class and [] in where block

Originally reported on Google Code with ID 191

Not sure whether this is a groovy compiler issue or spock issue. 

I get a compile error saying: "where-blocks may only contain certain parameterizations".
It happens when combining a class and empty list in a parameterized where block; e.g.
like this:

        where:
        theClass        | expectedResult
        Integer         | ["a"]  // works
        Integer.class   | ["a"]  // works
        Float           | []  // fails
        Float.class     | []  // fails
        Float           | new ArrayList() // works - i.e. a work-around

A complete spec reproducing compilation error is attached.

I am using Spock 0.6 snapshot with groovy 1.8

Reported by steinar.haugen on 2011-07-27 14:12:39

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- _Attachment: [PossibleEmptyListBugSpecification.groovy](https://storage.googleapis.com/google-code-attachments/spock/issue-191/comment-0/PossibleEmptyListBugSpecification.groovy)_

Start with the attached PossibleEmptyListBugSpecification.groovy and reproduce the where-block compilation error using Spock 0.6 snapshot with Groovy 1.8. Inspect validation of parameterizations involving Float or Float.class and an empty list; done means those examples compile without the reported error and have regression coverage.