Type error in type assertions

[HSMF]

The following snippet fails in the type checker.

package main

type T interface {
        Foo()
}

func compute(e T) int {
        v, ok := e.(interface {
                F() int
        })

        if ok {
                return v.F()
        } else {
                return 0
        }
}

The error seems to be that in order to type check x.(T), where x is of type S the type checker first checks that T implements S.

Since in the above snippet, v is only used if ok, it makes sense to allow the type assertion to fail.

12:27:40.434 [thread-4] ERROR viper.gobra.reporting.FileWriterReporter - Error at: <main.go:8:11> main.go:8:11:error: type error: type interface{ F } does not implement the interface T