RE: [sv-sc] RE: [sv-champions] Mantis 1728 - let

Shalom,

 

(a+b) is already a primary, and its parentheses are no guard against
context-dependent effects.

 

Primary vs. Expression is a syntactic distinction, not a semantic one.

 

n  Brad

 

From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com] 
Sent: Thursday, July 24, 2008 7:38 PM
To: Brad Pierce; sv-champions@eda.org
Cc: sv-sc@eda.org
Subject: RE: [sv-sc] RE: [sv-champions] Mantis 1728 - let

 

Hmm,

	 

	--- 6 ---

	There are two module declarations that begin

	 

	    module m(input bit clock);

	 

	But there are, unfortunately, still no 2-state wires in
SystemVerilog, so these should be

	 

	    module m(input var bit clock);

	 

	[SB] or 'input logic clock' or simply 'input clock', since there
does notseem to be any need in the examples for clock to be 2-state.

	 

	Also, example (f) has

	 

	module m(logic clock);

	 

	While not incorrect, this declares clock as inout, which was
probably not the intent.

	 

	More seriously, both examples (e) and (f) refer to both "clock"
and "clk". It needs to be consistent.

	 

	--- 7 ---

	"let_expression" should be added to "primary" in A.8.4, not
"expression" in A.8.3. 

	 

	[SB] I question that. Let expands to a macro-like substitution
and with parentheses. And that substitution semantics is an essential
part of let. As in the example in the Motivation introduction, let c = a
+ b,when c is instantiated, a and b are size-extended to the size of the
context. Conversely, if a or b is bigger than the size of the other nets
and variables in the context of the let instance, then those other nets
and variables are size-extended to the size of a or b, whichever is
bigger. That is not consistent with regarding a let_expression as a
primary.

	 

	Regards,

	Shalom

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