VHDL Issue Number:      0046 
Classification:         Language Definition Problem 
Language Version:       VHDL-87
Summary:                When are checks on resolution functions performed? 
Related Issues:          
Relevant LRM Sections:  2.4, 4.2 
Key Words and Phrases:  Resolution function, error check, Subtype indication 
Current Status:         ISAC-Approved 
1076-1993 Disposition:  Closed (All Issues Completely Addressed)
Disposition Rationale:  Section 2.4 line 383 was revised, Section 10.4.
Superseded By:          N/A
--------------------- 
Date Submitted:         1989/02/10 
Author of Submission:   Doug Dunlop 
Author's Affiliation:   Intermetrics, Inc. 
Author's Post Address:  4733 Bethesda Ave #415 
                        Bethesda, MD  20814 
Author's Phone Number:  (301) 657-3775 
Author's Fax Number:    
Author's Net Address:   dunlop@inmet.inmet.com 
----------------------- 
Date Analyzed:          1990/10/04
Author of Analysis:     Oz Levia 
Revision Number:        $Revision: 1.9 $
Date Last Revised:      $Date: 1995/08/03 00:26:32 $
 
 
Description of Problem 
---------------------- 
There is a question about when the checks in the second 
paragraph of LRM 2.4 get performed.  LRM sections 2.4 and 4.2 suggest they take 
place when a resolved signal is declared.  It is probably the intent and it 
makes more sense to perform these checks at the point of the subtype indication. 
E.g., if no signal is declared to be resolved with a particular resolution 
function but the resolution function does not meet the parameter and result 
type requirements of LRM 2.4, the VHDL is still an error. 
 
 
Proposed Resolution 
------------------- 
These checks will be performed at the point of the subtype 
indication. 
 
 
VASG-ISAC Analysis & Rationale 
------------------------------ 
The above proposed resolution is correct. 
 
 
 
VASG-ISAC Recommendation for IEEE Std 1076-1987 
----------------------------------------------- 
The following additions should be assumed to Sections 2.4 and 4.2: 
 
In Section 2.4 (page 2-7), add to the end of the  second paragraph so that it 
reads: 
 
" ... must also be that of the signal. The above rules are checked for 
at the point of subtype indication which contains the resolution 
function's name (see Section 4.2)." 
 
In section 4.2 (page 4-3), add to the end of the third full paragraph 
so that it reads: 
 
" ... , aliases, attributes, or other subtypes. It is an error if the 
function named does not meet the requirements of a resolution function 
(see Section 2.4)." 
 
 
VASG-ISAC Recommendation for Future Revisions 
--------------------------------------------- 
Change the LRM to reflect the above changes.