[Issue 23810] New: types from core.stdc can't be used in extern(C++) due to aliases being shared

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23810

          Issue ID: 23810
           Summary: types from core.stdc can't be used in extern(C++) due
                    to aliases being shared
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: druntime
          Assignee: nobody at puremagic.com
          Reporter: ryuukk.dev at gmail.com

ndf from IRC:

> Hello. I wonder is the following code supposed to compile or not? https://paste.ee/p/RHdiz


```
import core.stdc.stdio;

extern(C++) class Base
{
  public:
    void* LoadFromFilePointer(FILE* fp, int* err);
}

void main() {}
```

```
onlineapp.d(6): Error: function `onlineapp.Base.LoadFromFilePointer` cannot
have parameter of type `shared(_IO_FILE)*` because its linkage is `extern(C++)`
```


``FILE`` is aliased: ``alias shared(_iobuf) FILE;``

I personally suggest removing shared from the alias, and developer to let
choose what is ``shared``

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