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Subject: RE: Intermittent 'make' segfaults in Cygwin
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From: Stephen Bennett <sbennett AT accelrys DOT com>
Date: Wed, 21 Nov 2007 10:21:13 +0000
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>   Try using %CYGWIN%=error_start to get either gdb or dumper.exe 
attached at
> the exact moment of failure.  Check the user guide
> http://cygwin.com/cygwin-ug-net/using-cygwinenv.html
> for full usage information.

Thanks for the tip. That was enough to get a stack trace with no symbol 
information -- not too helpful on its own. When I rebuilt make with debug 
information from the Cygwin source package, I was completely unable to 
reproduce the segfaults -- four complete builds have now succeeded in a 
row, compared with previously when each build would show between 1 and 
about 7 segfaults.

I'd say this is beginning to look like a weird compiler and/or 
optimisation bug, given that it happens frequently with the Cygwin package 
and not at all with an almost un-optimised build (CFLAGS="-O1 
-fno-inline-functions -ggdb3"). Unfortunately I don't have any sort of 
reduced test case demonstrating it, but if I get a chance I'll try to 
narrow down what specifically is triggering it. Is there an easy way to 
find which compiler and optimisation settings were used to build the 
current Cygwin make package?


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