https://issues.dlang.org/show_bug.cgi?id=17159

          Issue ID: 17159
           Summary: Behavior of unions at compile time is not documented
           Product: D
           Version: D2
          Hardware: All
               URL: https://dlang.org/spec/function.html#interpretation
                OS: All
            Status: NEW
          Keywords: CTFE, spec
          Severity: normal
          Priority: P1
         Component: dlang.org
          Assignee: nobody@puremagic.com
          Reporter: dfj1esp02@sneakemail.com

E.g. access to overlapped fields is not allowed.

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