[Issue 16673] improve cyclic module imports checker

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16673

--- Comment #5 from Martin Nowak <code at dawg.eu> ---
And obviously nested functions within the ctor.
This would turn all ctors in Higgs to standalone ctors. Data initialization is
the biggest use-case for ctors, so this would likely solve many cyclic module
issues.

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