Extension method can be extension_foo

[bishabosha]

Minimized code

extension (x: Any) def extension_foo: String = "foo"

Output

compiles ok

Expectation

any other definition can not start with extension_, so I would expect this not to work.

the desugared method is extension_extension_foo, should there be an extra check in Desugar for the unexpanded extension method name beginning like that?

[odersky]

the desugared method is extension_extension_foo, should there be an extra check in Desugar for the unexpanded extension method name beginning like that?

I think so, yes.