https://issues.dlang.org/show_bug.cgi?id=20419

          Issue ID: 20419
           Summary: is(missing == module/package) results in unknown
                    identifier
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: moonlightsentinel@disroot.org

is(stuff == module) and is(stuff == package) raise an error if "stuff" is an
unknown symbol. All other non-type checks (e.g. stuff == class) simply evaluate
to false because the spec only requires "stuff" to be syntactically valid.

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