Xref: utzoo comp.lang.pascal:3821 comp.sources.wanted:12556
Path: utzoo!attcan!uunet!bu.edu!xylogics!transfer!crackers!m2c!umvlsi!dime!smectos!eli
From: eli@smectos.gang.umass.edu (Eli Brandt)
Newsgroups: comp.lang.pascal,comp.sources.wanted
Subject: Re: Mouse support for Turbo Pascal 5.5
Message-ID: <17165@dime.cs.umass.edu>
Date: 19 Jul 90 17:04:48 GMT
References: <90197.213141EX0@psuvm.psu.edu> <1990Jul18.055406.17988@uwasa.fi>
Sender: news@dime.cs.umass.edu
Reply-To: eli@smectos.CS.UMASS.EDU (Eli Brandt)
Followup-To: comp.lang.pascal
Organization: University of Massachusetts, Amherst
Lines: 46

program BugTest;
{
Demonstrates a bug in the integrated debugger in TP 5.5

   In the IDE, run the program to the marked line.  Then evaluate v1 or its
components.  Note the absurd results. (I got 1.8E-37, 4E-5, 5E-5 or some such)
This may be a result of the debugger's looking in the old stack context; I
don't know.  Also note that the values print out correctly; the fault is that
of the debugger.  The simplest way to work around this problem is to declare v1
as a var parameter, as indicated.  As the compiler treats the existing declar-
ation as a var parameter anyway, this makes no functional difference to the
program.
   Note: the same results (well, different nonsense) are obtained with
         Turbo Debugger 1.5

System:  IBM PS/2 50
         DOS 3.3
         Turbo Pascal v5.5 (file size 156321; date 5-2-89)
         No autoexec.bat; no config.sys


Eli Brandt 7/10/90
}

type
  vec3 = record
           x, y, z: real;
         end;

procedure ReceiveVec(v1: vec3);            { or "var v1: vec3" to fix       }
begin                                      { <-- run to this line      ***  }
  writeln(v1.x, ' ', v1.y, ' ', v1.z);
end;

procedure passvec;
var
  v: vec3;

begin
  v.x := 1;  v.y := 2;  v.z := 3;
  ReceiveVec(v);
end;

begin
  passvec;
end.