[Issue 12578] Allow local function overloading

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=12578

--- Comment #1 from monarchdodra at gmail.com ---
Also relevant: The declaration of nested structs/classes:
https://github.com/D-Programming-Language/phobos/pull/2074/files

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