ISAC: new IR

Here is a new IR2055: Prohibition on assignment of protected types not
normative
Let's discuss this at our meeting.

Chuck Swart

VHDL Issue Number: 2055

Language_Version VHDL-2002
Classification Language Definition Problem
Summary Prohibition on assignment of protected types not normative
Relevant_LRM_Sections 3, 4.3, 8.4, 8.5
Related_Issues
Key_Words_and_Phrases protected types, assignment
Authors_Name Peter Ashenden
Authors_Phone_Number +61 (8) 8339 7532
Authors_Fax_Number +61 (8) 8339 2616
Authors_Email_Address peter@ashenden.com.au
Authors_Affiliation Ashenden Designs
Authors_Address1 PO Box 640
Authors_Address2 Stirling, SA 5152
Authors_Address3 Australia

Current Status: Submitted

Superseded By:

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Date Submitted: 19 January 2005
Date Analyzed:
Author of Analysis:
Revision Number: 0
Date Last Revised:

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

Clause 3 defines a basic operation and includes assignment (in assignment statements and initializations).
    
    Clause 4.3 prohibits initialization of objects of protected types:
    
    - in 4.3.1.1, by virtue of a constant not being of a protected type;
    
    - in 4.3.1.2, by virtue of a signal not being of a protected type;
    
    - in 4.3.1.3, by virtue of a variable of a protected type not
      being allowed to have an initial value expression in its
      declaration;
    
    - in 4.3.2, by virtue of a default expression being illegal if the
      subtype indication of the interface declaration denotes a
      protected type.
    
    The informative notes in clause 8.4 specify that the target of a
    signal assignment statement must not be of a protected type. This
    is a ramification of the requirement that signals not be of
    protected types.
    
    Similarly, the informative notes in 8.5 specify that the target of
    a variable assignment statement must not be of a protected type.
    However, this does not follow as a ramification of any normative
    specification.

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

The text of notes 2 and 3 in 8.5 should be moved to the normative text of 8.5.

VASG-ISAC Analysis & Rationale
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TBD

VASG-ISAC Recommendation for IEEE Std 1076-2002
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TBD

VASG-ISAC Recommendation for Future Revisions
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TBD

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Received on Thu Jan 20 12:27:01 2005