https://issues.dlang.org/show_bug.cgi?id=21941

          Issue ID: 21941
           Summary: dtoh:Warning about keyword identifiers should include
                    C extensions
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: trivial
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: ibuclaw@gdcproject.org

See link for list of current keywords:

https://github.com/dlang/dmd/blob/abc23d1126605957f663b5f43a719394e32985a0/src/dmd/dtoh.d#L439

I didn't anticipate anyone would add a enum member named __attribute__.

https://github.com/dlang/dmd/blob/abc23d1126605957f663b5f43a719394e32985a0/src/dmd/tokens.d#L294

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