[Issue 20047] call of static nested function ignores purity

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20047

--- Comment #1 from Mike Franklin <slavo5150 at yahoo.com> ---
This behavior was introduced in https://github.com/dlang/dmd/pull/4344 as a fix
to Issue 14039

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