https://issues.dlang.org/show_bug.cgi?id=21145

          Issue ID: 21145
           Summary: No introspection access to a class' invariant
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: andrei@erdani.com

It is offered part of TypeInfo_Class. Should be available as a trait.

This blocks https://github.com/dlang/druntime/pull/3174.

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