Strange behavior in debugging of bug #5245, looking for comments

[Robert Shearman]

Alex Villací­s Lasso wrote:

> Last weekend, I was trying to trace down bug #5245 (Run-Time error '6' 
> overflow in terragen). With current CVS, the bug manifests itself with 
> an "Overflow" dialog when starting up Terragen. However, this bug does 
> *not* go away with a native oleaut32.dll (taken from win98), so this 
> does not seem like an OLE bug. When running the program with the 
> debugger, the underlying exception trapped before displaying the 
> dialog reads "inexact float result", with a backtrace that comes out 
> of the bowels of msvbvm60.dll (weird - NOT inside Terragen.exe, and 
> NOT inside Terragen.dll). However, if the user types "pass" at the 
> debugger prompt, the dialog box does not appear, and the program 
> continues "normally". The exception occurs again whenever a File Open 
> dialog is dismissed, and again, typing "pass" lets the program run 
> normally.
>
> Several questions:
> - Can programs that execute floating-point instructions get the 
> "inexact float result" exception without any explicit setup, or do 
> they have to call some API in order to enable this notification? If 
> so, is it described in MSDN?


I believe it is an exception code raised by VB itself, not the result of 
a floating point operation. I've seen it before and it usually means 
that something unexpected happened under the covers in the VB runtime. 
However, I would have expected it to be a bug inside oleaut32, but that 
appears not to be the case here. Have you tried running with native 
ole32 and rpcrt4 as well to see if the bug disappears?

> - Is the described behavior normal for the "pass" command? I was 
> expecting the command to make the app show the Overflow dialog and 
> then exit.


I don't think so. It should have the same behaviour as when running.

-- 
Rob Shearman