Currently astutil.PathEnclosingInterval doesn't handle enclosing node for comments correctly. Examples:

1. Pos on <> returns whole *ast.File as enclosing node, but should return *ast.CommentGroup.

// main is main <>
func main() {
}

2. Pos on <> returns main function's *ast.BlockStmt with all statements (*ast.CommentGroup is not included in this node), but should return *ast.CommentGroup.

func main() {
     fmt.Print("hi") // Print prints hi <>
     fmt.Print("bye")
}

By looking at unit tests I can see that this was intentional behaviour https://github.com/golang/tools/blob/master/go/ast/astutil/enclosing_test.go#L156.

@alandonovan What do you think we can do here? Is it fixable? Was it some requirements for other tools to work this way? Thanks a lot.

Background:
x/tools/internal/lsp uses PathEnclosingInterval for autocompletion and I was working on preventing autocompletion inside comment blocks. I made a fix for 1 case which is still kind of hacky because it traverse *ast.File and checks if node on given pos is actually *ast.Comment , but for 2 case there is no easy way to fix it and the best way would be to fix PathEnclosingInterval.

/cc @stamblerre