Re: enhancement/287: `compatibility - backward compatibilitycompilerdirectives

From: Steven Sharp (sharp@cadence.com)
Date: Fri Jun 18 2004 - 11:10:01 PDT

  • Next message: Stuart Sutherland: "RE: enhancement/287: `compatibility - backward compatibilitycompilerdirectives"

    The following reply was made to PR enhancement/287; it has been noted by GNATS.

    From: Steven Sharp <sharp@cadence.com>
    To: etf-bugs@boyd.com, Shalom.Bresticker@freescale.com
    Cc:
    Subject: Re: enhancement/287: `compatibility - backward compatibilitycompilerdirectives
    Date: Fri, 18 Jun 2004 14:10:18 -0400 (EDT)

    > However, if "1364-2001 compatibility" would require
    > him to disable any and all features added in later versions of the
    > standard, that would be much harder for a vendor to implement,
     
     In fact, if the earlier versions of the standard are not readily
     available, this is a bigger issue than just implementation effort.
     
     I believe that if this directive is added to the standard, that the
     behavior required to be compliant needs to be fully specified in the
     standard also. I don't believe that referring to an earlier obsoleted
     version of the standard is a valid specification.
     
     Trying to specify everything that has changed from all previous versions
     of the standard is impractical. Restricting it to something smaller,
     such as just keywords, or just the things that are not backward-compatible,
     would make both specification and implementation much simpler.
     
     
    > It is true that there are a few things which actually change from one
    > version of the standard to the next, as opposed to added extensions,
    > such as the use of bit 31 of an MCD, but those cases have been quite few
    > and relatively unimportant.
     
     The change in x/z-extension behavior for unsized literals is the only other
     one I can think of.
     
     Steven Sharp
     sharp@cadence.com
     

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