[Issue 20362] dmd fails to infer scope parameter for delegate

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20362

--- Comment #1 from Atila Neves <atila.neves at gmail.com> ---
Note: the code was taken out of context, but the reason it's *really* important
is that it occurs in Throwable.toString

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