[Issue 17423] pointer assignment to `this` in member function is not accounted for

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17423

--- Comment #6 from Walter Bright <bugzilla at digitalmars.com> ---
The opApply is actually working correctly. The bug is that the dlg parameter
was incorrectly inferred as `scope`.

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