VHDL Issue Number:      0190
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                VPI Issue 14 -- Prefixes in USE clauses
Related Issues:         TBD
Relevant LRM Sections:  TBD
Key Words and Phrases:  TBD
Current Status:         Submitted
1076-1993 Disposition:  Superseded (ISAC Issues Outstanding)
Disposition Rationale:  N/A
Superseded By:          1070
-----------------------
Date Submitted:         1991/03/15
Author of Submission:   J. R. Armstrong
Author's Affiliation:   Virginia Polytechnic Institute and State University
Author's Post Address:  Bradley Department of Electrical Engineering
                        Virginia Polytechnic Institute and State University
                        Blacksburg, VA 24061
Author's Phone Number:  (703) 231-4723
Author's Fax Number:    
Author's Net Address:   JRA@VTVM1.CC.VT.EDU
-----------------------
Date Analyzed:          TBD
Author of Analysis:     TBD
Revision Number:        $Revision: 1.10 $
Date Last Revised:      $Date: 1995/05/13 21:53:48 $


Description of Problem
----------------------
  Can  the  same  prefix  be  used  in  multiple
  selected_names  in  a  USE  clause?  For  example,  is  "use
  work.definework.all, work.definework;" allowed?

  Test File: CH10/S04/01010104.vhd

  Comments:       (from      MCC)      The      line      "use
  work.definework.all,work.definework;" is in error since  the
  first  part  of  the clause "use work.definework.all" causes
  the name WORK to become not directly visible. Thus, the sec-
  ond part of this clause  "use  work.definework"  is  invalid
  since  the  name  WORK is now not directly visible. MCC sug-
  gests  changing  the  line  to  read  "use  work.definework,
  definework.all;"


  -- ##A4001114281FFA400121A400231**********************************************
  --+ File: [SUITE.CH10.S04]01010104.VHD
  --
  --+ Copyright (c) 1987, 1988 by CAD Language Systems, Inc.  All rights reserve
  --
  --+ LRM_version: IEEE Std. 1076-1987
  --
  --+ Subsets:
  --
  --+ Description:
  --
  --+ Test_point - (100400_010101) "A use clause achieves direct visibility of
  --  declarations that are visible by selection."
  --
  --+ Test_objective -(4) Test that when a declaration existing outside the scop
  --  of the immediate design region is needed, that a use clause can make that
  --  declaration visible. In addition, the library section of the LRM (section
  --  11.2) states that the use clauses:
  --             library STD, WORK; use STD.STANDARD.all
  --  should be implicit.  This test should succeed.
  --
  --+ References: Secondary LRM Coverage: (100400_010201)
  --                                      (100400_020301)
  --
  --+ Instructions: None
  --
  --+ Keywords: use clause, declaration, library, visibility
  --
  --+ Test_Results: Expect_success. Output_Checked.
  --
  --+ Test_Type: Locally Static Semantic
  --
  --+ History: Created MAT/CLSI 08-30-88
  --           Corrected KSC/VT 12-22-89
  --           Corrected CHC/VT 5-4-90
  --
  --+ Comments: CLSI-FILE: [000000.SCOPE.USECLAUSE]08
  --            MCC claimed that the order of selected names in the
  --            use clause is significant.
  --            This will be sent to VASG for clarification.
  --
  -- ***************************************************************************
  package definework is
   type work is array(0 to 31) of BIT;
  end definework;


  use work.definework.all,work.definework;
  entity E is
      port (P : in  bit);
  end E;

  architecture D3 of E is
      use  work.definework;
  begin
      process (P)
  -- This succeeds because type work is defined in package definework,
  -- there is no conflict with library "work"
       variable doit : definework.work ;  -- No_failure_here
      begin
      end process;
  end D3;


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


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


VASG-ISAC Recommendation for IEEE Std 1076-1987
-----------------------------------------------
TBD


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