[Issue 519] Invariant not called from autogenerated class/struct constructor/destructor

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=519

--- Comment #21 from Bolpat <qs.il.paperinik at gmail.com> ---
Maybe this can be done via a caller-side lowering:

The expression `T(args...)` would become
```d
{
    auto result = T(args...);
    assert(() @trusted { return &result; }());
    return result;
}()
```

The @trusted block is to be able to take the address without dip1000.

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