VHDL Issue Number:     2000

Language_Version:      VHDL-2000
Classification:        Language Definition Problem
Summary:               Where may/must deferred constant declaration appear
Relevant_LRM_Sections: P1076 2000/D1 4.3.1.1
Related_Issues:
Key_Words_and_Phrases:
Authors_Name:          Paul Graham
Authors_Phone_Number:  734-994-3223
Authors_Fax_Number:
Authors_Email_Address: pgraham@cadence.com
Authors_Affiliation:   Cadence
Authors_Address1:
Authors_Address2:
Authors_Address3:

Current Status:        VASG-Approved

Superseded By:

------------------------
Date Submitted:        2 March 2000
Date Analyzed:         28 October 2002
Author of Analysis:    Chuck Swart
Revision Number:       2
Date Last Revised:     09 May 2005

Description of Problem
----------------------

In the old days, section 4.3.1.1 said, referring to a deferred constant
declaration: such a constant declaration may only appear in a
package declaration.     

In 2000/D1, this section says: such a constant declaration must appear
in a package declaration.

     I think the first form was more accurate.  Consider the
difference between employees may only smoke outside the building and
employees must smoke outside the building

The revised LRM wording makes it seem that every package declaration
must contain a deferred constant declaration.


Proposed Resolution
-------------------
TBD

VASG-ISAC Analysis & Rationale
------------------------------

The wording used in VHDL-2000 is at least confusing, and, strictly speaking,
incorrect.

VASG-ISAC Recommendation for IEEE Std 1076-2002
-----------------------------------------------

Interpret the LRM as it was intended: the only legal declarative
region in which a deferred constant may occur is in a package header.

VASG-ISAC Recommendation for Future Revisions
---------------------------------------------
Replace the sentence in 4.3.1.1 which reads:

"Such a constant declaration must appear in a package declaration."

by something like:

"It is an error if a deferred constant declaration appears anywhere other than
in a package declaration."


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