Protected module members -- regression?

[Mike Parker]

I've long had it in my mind to do a sort of "D for C++/Java/C#" 
programmers sort of series on the blog. Inspired by the recent 
conversation about private-to-the-module, I started one on that 
topic. Then I encountered this:

```
module a;

protected int wrong;
```

```
module b;
import std.stdio;
import a;

int main() { writeln(wrong); }
```

I've always understood that protected module members are illegal. 
The docs explicitly say so. Yet the declaration of `wrong` 
compiles. Instead, trying to use it results in the deprecation 
message about symbol visibility that was added a couple years 
back when access modifiers were incorporated into symbol lookup.

I assume this is a regression and filed it as such [1], but I'm 
curious if the compiler has ever actually complained about 
protected module members.

[1] https://issues.dlang.org/show_bug.cgi?id=19340