Free Pascal IDE, Runtime error 4216927?!
lazarus / 62-General

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Rick314 · 2015-02-27 02:27

See the 2 attached images and test code below.  Between the two images
is a "Step Over" (F8 in the IDE).  Prod64 : QWord (64-bit unsigned)
has value 3618239625 = $00000000d7a9f489.  I want to put the 32 LS
bits into TempDivIntoIt : Longint (32-bit signed).  Executing the test
code below produces the desired output "3618239625 -676727671", but
the single-step in the IDE produces Run Time Error 4216927, Error
Address $00000000, loss of Watch Window values, and what appears to be
a messed up call stack.

How do I to interpret these results?

What should my path forward be?  (Bug report?  Workarounds?  Debugging
suggestions? ...)


program bugtest;
var
   TempDivIntoIt :Longint;
   Prod64 :QWord;
begin
   Prod64 := 3618239625;
   TempDivIntoIt := Longword(Prod64);
   writeln(Prod64, ' ', TempDivIntoIt);
end.

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engkin · 2015-02-27 03:26

Quote from: Rick314 on February 27, 2015, 03:27:45 amHow do I to
interpret these results?

I don't use this IDE, but based on the call stack in the second image,
it is a range check error (fpc_rangeerror). The error message is
vague. The error happened because of the typecast Longword(Prod64). A
proposed solution is to bypass the check at this point:
Code: [Select]   {$Push}
   {$RangeChecks Off}
   TempDivIntoIt := Longword(Prod64);
   {$Pop}

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Rick314 · 2015-02-27 04:55

Thank you engkin.  Your suggestion allowed me to go forward and
continue what I was doing.