The experimental translation tool accepts a range of syntaxes. It does not strictly enforce the rules required by the design draft.

@ianlancetaylor But where to find a document for all possibilities without knowing the implementation details? How can one classify bugs apart from expected behaviors?

go2go is an experimental tool, and the main purpose of the tool is to see if the generics design draft provides the semantics that people need and want. The syntax is not the point of the tool. Report bugs where the behavior is not what you expect, or where you can't do what you want. Bugs about syntactic details are less interesting, because the syntax is much easier to change than the semantics.

That said, we will soon be updating the dev.go2go branch to default to only permitting the syntax described in the design draft.

Thanks.