RE: [sv-bc] FW: Can a keyword be used as identifier if context is clear?

Just to be fair, note that the vendor that Ben Cohen said allows the
"instance" keyword is not the one employing Steven Sharp.

Shalom

> -----Original Message-----
> From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org]
On
> Behalf Of Steven Sharp
> Sent: Saturday, May 13, 2006 1:58 AM
> To: sv-bc@server.eda.org
> Subject: RE: [sv-bc] FW: Can a keyword be used as identifier if
context
> is clear?
> 
> As the person who requested the "1364-2001-noconfig", let me provide a
> few more details of the situation.  We deliberately chose to use what
> became the "1364-2001-noconfig" keyword set, for two reasons.
> 
> 1. All the keyword conflicts in our collection of legacy Verilog-1995
>    customer designs were with keywords from configs.  Without those
>    keywords, our users had nearly 100% backward compatibility with
>    Verilog-1995.  With those keywords, they only had 85% backward
>    compatibility.  This is presumably representative of all legacy
>    designs of all Verilog users.
> 
> 2. There were reasons it was undesirable to allow configs in Verilog
>    source files.  At that point in time, there seemed to be support
> within
>    the 1364 BTF for disallowing them there.  And as it turned out, a
>    mistake in the 1364-2001 BNF disallowed configs in Verilog source
> files.
>    If they were not allowed in Verilog source files, there was no
reason
> to
>    reserve their keywords there.
> 
> Ultimately, the 1364 committee decided to allow configs in Verilog
> source
> files after all.  The mistake in the 1364-2001 BNF was fixed in 1364-
> 2005.
> As part of the compromise for this, I requested the addition of the
> "1364-2001-noconfig" version specifier.  We could have used this as a
> nonstandard specifier, but preferred to have it standardized.  This
also
> makes it available to any other users who want to be able to compile
> both
> 100% of Verilog-2001 code and 99% of legacy Verilog-1995 code with a
> single
> dialect.  It is a very useful dialect in practice.
> 
> It may also be reasonable to have a "1364-2005-noconfig" version
> specifier.
> Since configs are definitely allowed in Verilog-2005 source files, it
> could
> not handle source files containing configs.  However, in practice
those
> are
> probably rare.  And since "uwire" is the only new keyword in
1364-2005,
> this
> dialect would still handle nearly 100% of Verilog-1995 designs.  This
> may be
> another useful dialect in practice.
> 
> The similar argument for  "1800-2005-noconfig" is weaker.  With all
the
> new 1800 keywords, less than half of legacy Verilog designs will
compile
> under "1800-2005", with or without "-noconfig".  So it doesn't really
> help
> much.  However, I do like the suggestion that "-noconfig" be allowed
as
> a
> qualifier to each of these version specifiers.
> 
> Note that in the future the version specifiers may need to deal with
> Verilog-AMS keywords.  Having independent qualifiers to allow
inclusion
> of the AMS keywords with each of the existing 1364 and 1800 versions
> is cleaner and more flexible than having to provide a specific version
> specifier with a keyword list for each combination.
> 
> Steven Sharp
> sharp@cadence.com