What is this undefined reference with -betterC about?

[Dennis]

On Wednesday, 16 June 2021 at 14:38:10 UTC, jfondren wrote:
> What do I change to
> 1. a script like this that uses hostname
> 2. the hostname module
>
> so that both can be built with -betterC when and only when
> the script is using -betterC?

That's currently the situation: you can only build when both are 
betterC or else you get a linker error. It has to be a linker 
error, dmd cannot know at the time of compiling project A how 
project B is going to be compiled and vice versa.

It noticed your code looks like this:
```D
version(D_BetterC) {
     char* hostnamez;
} else {
     immutable char* hostnamez;
}
```

The different types result in different mangles, causing the 
linking errors. Why not simply give them the same type?