Is it possible to generate docs + json file without succesful compilation?

[Bradley Chatha]

I want the compiler to generate both documentation (`-D`) as well 
as the AST Json file (`-X`) without having to worry about being 
able to actually compile the provided D files.

e.g.

```bash
ldc2 -o- -c -X -D --oq file.d
```

However the above command can produce errors such as:

```
Error: cannot find input file `yadayada.d`
```

Is there a way to do such a thing currently, since I'd rather not 
have to deal with having compilation errors when I just want the 
ast + comments?