-preview=in deprecation warning

[Jack Applegame via Digitalmars-d-learn]

Can anyone help me get rid of this depreciation?

```d
struct Foo {
        string foo;
        string getFoo() const @safe { return foo; }
}
size_t bar(in Foo foo) @safe {
        return foo.getFoo().length;
}

void main() {
        Foo("hello").bar().writeln();
}
```
```sh
$ ldc2 -preview=in --run foo.d
foo.d(9): Deprecation: scope variable `foo` assigned to non-scope 
parameter `this` calling `getFoo`
```
```sh
$ ldc2 --version
LDC - the LLVM D compiler (1.32.1):
  based on DMD v2.102.2 and LLVM 15.0.7
```