ISAC: IR 2080 analyzed

If we have time, lets discuss/vote on this at today's meeting.

Chuck Swart



VHDL Issue Number:        2080

Language_Version          VHDL-2002
Classification            Language Definition Problem
Summary                   Case expression should include parenthesized expression
Relevant_LRM_Sections     8.8, page 127, para starting "If the expression is the name of an object..."
Related_Issues            
Key_Words_and_Phrases     case statement, locally static subtype
Authors_Name              Peter Ashenden
Authors_Phone_Number      +61 414 709 106
Authors_Fax_Number        
Authors_Email_Address     peter@ashenden.com.au
Authors_Affiliation       Ashenden Designs
Authors_Address1          
Authors_Address2          
Authors_Address3          

Current Status:           Submitted

Superseded By:

------------------------
Date Submitted:           26 December 2005, Revised 13 January 2006
Date Analyzed:            02 February 2006
Author of Analysis:       Chuck Swart
Revision Number:          1
Date Last Revised:        Chuck Swart

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

Clause 8.8, in the bottom paragraph of page 127, specifies that the
expression in a case statement must have a locally static subtype. It
lists forms of expressions that can occur, but omits a parenthesized
expression in which the contained expression has a locally static
subtype. (This omission was earlier pointed out by John Ries, but has
not formally been reported and tracked.)

Moreover, on the top of page 128, the clause lists allowed forms for
an expression of a one-dimensional array type. Similarly, the list
omits a parenthesized expression containing an otherwise allowed form
of expression.

Proposed Resolution
-------------------

In the bottom paragraph of page 127, add the following to the end of
the last sentence: ", or if the expression is an expression described
in this paragraph and enclosed in parentheses".

In the list at the top of page 128, add a further list item:

  -- An expression described in this list and enclosed enclosed in
     parentheses


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

The submitter is correct.

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

Interpret the LRM as if the recommendation for future revisions has
been adopted.

VASG-ISAC Recommendation for Future Revisions
---------------------------------------------

Make the LRM changes proposed by the submitter.


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