[Issue 22040] New: dip1000: foreach ref can escape scope array

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22040

          Issue ID: 22040
           Summary: dip1000: foreach ref can escape scope array
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Keywords: safe, Vision
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: dkorpel at live.nl

This is correctly rejected:
```
ref int f(ref scope int[] arr) {
    foreach(ref e; arr) 
        return e; // Error: scope variable `__r2` may not be returned
    assert(0);
}
```

This isn't: (`scope` => `return scope`)
```
ref int f(ref return scope int[] arr) {
    foreach(ref e; arr) 
        return e; 
    assert(0);
}
```

The `return` applies to the `ref arr`, not the `int[]`. This is another case of
the compiler conflating `return ref` and `return scope` like in issue 21868.

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