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Conference clt::dec_pascal_bugs

Title:DEC Pascal Bug Reports
Notice:New kit announcement in TURRIS::Pascal conference
Moderator:TLE::GARRISON
Created:Wed Sep 09 1992
Last Modified:Fri May 30 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:838
Total number of notes:3659

826.0. "Problem when two externals are actually at the same address" by TLE::GARRISON (Meg) Mon Feb 10 1997 13:32

The following program shows a problem we discovered while looking into note 810.

The side effects package doesn't handle EXTERNALs exactly right in strange cases
like the one below, where two externals actually represent the same variable.
(kind of like pointer aliasing) 

    program bug(output);
    
    var
       myglob : [GLOBAL] integer;
       myvar : [EXTERNAL (myglob)] integer;
       myvar2 : [EXTERNAL (myglob)] integer;
    
    begin
       myvar := 10;
       write(myvar);
    
       myvar2  := 100;
       write(myvar, myvar2);
       write(myvar);
       write(myglob);
    end.

The compiler gets the answer here as 


        10        10       100        10       100
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