[Issue 18757] static invariant{} should either work or not be valid syntax

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18757

--- Comment #6 from FeepingCreature <default_357-line at yahoo.de> ---
In my opinion, static this sets the precedent that static + class-level feature
= module-level feature.

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