Existence of mains in a class with a parameterful constructor leads to cbt fail

[buzden]

Consider I have (accidentially or not) some class X which has def main(args: Array[String]): Unit. CBT considers this as one of the variants of possible entry points during cbt run unless the class is abstract.

This behaviour is not fatal but a little bit annoying when you accidentially have written class instead of object and everything works fine with cbt but does not work with other tools (e.g. running with pure scala runner). In the code it's written that it's done because of dottydoc.

The really strange behaviour of cbt is when you have a _{^{really strange}} class having both constructor parameters and def main, something like this:

class X(whatever: Int) {
  def main(args: Array[String]): Unit = ???
}

Having this leads to (guess what):

Exception in thread "main" java.lang.InstantiationException: X
        at java.lang.Class.newInstance(Class.java:427)
        at cbt.reflect.Module$class.typeStaticMethod(reflect.scala:168)
        ...
Caused by: java.lang.NoSuchMethodException: X.<init>()
        ...

So, generally, cbt's reflection sublibrary assumes that it works with classes having a constructor with empty parameters list when talking about static methods (typeStaticMethod(Method) function).

[cvogt]

fix in #587, let's keep this open to still add a test as described there. Probably by copying cbt/test/simple, adding the suggested classes and calling something like .mainMethods on the build and check it doesn't throw