[Issue 22128] opApply delegate can escape scope without duly invoking GC allocation

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22128

--- Comment #1 from Walter Bright <bugzilla at digitalmars.com> ---
If `scope` is added just before `int delegate`, the `_dlg = dlg;` will be
diagnosed as an error.

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