[Dwarf-Discuss] constants updates, minor DWARF standard upgrade?

Michael Eager eager@eagerm.com
Fri Jul 20 19:53:55 GMT 2012

On 07/20/2012 11:46 AM, Cary Coutant wrote:
> For things like new tags, attributes, language codes, etc., we have
> occasionally given out assurances that the assigned numbers were safe
> to use once discussion was complete and the issue was accepted. In
> most cases, it's then OK to use these without bumping the DWARF
> version number, since clients are supposed to be able to tolerate
> unknown values (although binutils is a notable exception). For
> DW_LANG_Go, we did in fact issue such an assurance.

The DWARF Committee does give any assurances that any proposal will be
accepted, or that any proposal will be accepted without modification.
As Ron pointed out, only a released DWARF specification can be
considered authoritative.  No assurance was given with regard to any
proposal for adoption in DWARF Version 5, nor has any ever been given
prior to previous versions of the DWARF standard being released.

As Ian mentioned, when I indicated "Should be OK", that is not an
assurance that the assignment of a value for DW_LANG_Go would be
accepted as proposed, only that I thought that it was likely.  As Ian
said, reliance on this opinion is taken at GCC's risk.

DWARF contains facilities for user extensions and we encourage
compiler developers to use this methodology.  If developers decide,
for whatever reason, to not use the extension facilities built
into DWARF, there is a risk that they will have reverse or modify
this decision at some future date.  That said, we are cognizant of
these changes and will try to accommodate them, but we make no
guarantee or assurances that this will happen.

I hope this clarifies this question.

Michael Eager	 eager at eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077

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