Subject: RE: [sv-bc] Question on void-returning functions
From: Warmke, Doug (doug_warmke@mentorg.com)
Date: Thu Aug 28 2003 - 16:20:00 PDT
Thanks for the speedy responses, Brad and Dave.
Regards,
Doug
> -----Original Message-----
> From: Dave Rich [mailto:David.Rich@synopsys.COM]
> Sent: Thursday, August 28, 2003 3:02 PM
> To: Warmke, Doug
> Cc: 'sv-bc@server.eda.org'
> Subject: Re: [sv-bc] Question on void-returning functions
>
>
> Hi Doug,
>
> I believe you have found a mistake in the the BNF.
>
> | { attribute_instance } void'(function_call)
>
> should have been added to statement_item and function_statement_item,
> instead of primary. Then it will agree with the LRM
>
> I propose that we
>
> A) remove from primary production in A.8.4
>
> | void'(function_call)
>
>
> B) Add to both the statement_item and
> function_statement_itemproductions
> in A.6.4
>
> | { attribute_instance } void'(function_call)
>
> I just typed this up and see that Brad already filed BC-65 for this
> issue. Now it has a proposal
>
> Dave
>
> Warmke, Doug wrote:
>
> >Hi SV-BC,
> >
> >We are wondering about the LRM treatment of discarding fn
> results via a
> >cast to void:
> >
> >a. "Function calls are expressions unless of type void, which are
> >statments."
> > LRM 10.3.1. This certainly seems reasonable.
> >
> >b. Then we can effectively turn a non-void fn call into a
> void fn call
> > via casting (LRM 10.3.2):
> > "...using the void data type to discard a function's
> return value,
> > which is done by casting the function to the void type:
> > void'(some_function());
> >
> >c. Note that the example above shows a the void cast-fn as
> essentially a
> > stand-alone stmt, not part of an expression. This makes
> perfect sense,
> > since we are effectively turing the fn into a void fn,
> which 10.3.1 says
> > are statements.
> >
> >d. However, in the grammar, we have a void-cast-fn not as a
> statement,
> > but as a 'primary' under A.8.4:
> > primary ::= number
> > | ...
> > | function_call
> > | void'(function_call)
> > |...
> >
> >e. Is this just an oversight, or are we missing out on
> something here?
> > In a syntactic sense, one would expect to see a void cast
> as a statement
> >--
> > just like the LRM example. Otherwise, as a primary, it
> supposedly can
> >appear
> > in range expressions, with binary operators, etc.
> (A.8.3), which makes no
> > semantic sense for void.
> >
> >f. The reason for caring is to see if one can handle void-fn-calls
> > and cast-to-void-fn-calls in as similar way as possible.
> >
> >Thanks and regards,
> >Doug Warmke
> >
> >
> >
> >
>
> --
> --
> David.Rich@Synopsys.com
> Technical Marketing Consultant
> http://www.SystemVerilog.org
> tele: 650-584-4026
> cell: 510-589-2625
>
>
>
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