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[Mingw-users] bizarre problem, need help from a mingw developer




Hi,

What started out as a bug in the windows version of Inkscape

   https://bugs.launchpad.net/inkscape/+bug/1538361

has been tracked into some very peculiar behavior associated with the 
poppler library in devlibs.  With a tiny test program the bug is 
triggered by merely linking in that library, none of its functions are 
called (at least not explicitly)!  What happens is that a code snippet 
like this:

    double val=1.0;
    printf("%lf\n",val);

emits 0.0 instead of 1.0. (Within inkscape the bug is much worse, it 
looks like it is formatting random locations in memory, and extremely 
long strings of random digits can be returned.) Skip linking in poppler 
and it works as it should.  There is some sort of memory access issue 
flagged by Dr. Memory in the case where it fails, but not with enough 
information to indicate which part of poppler is responsible.  Or at 
least, not enough information for _me_ to figure it out.  However when 
the program is linked without poppler Dr. Memory sees no issues, and of 
course the program runs as it should.

Discussion on the Poppler mail list about this has revolved around the 
hypothesis that some sort of confusion by the linker results concerning 
which version of the printf() functions end up being used.

A test program, a debug version of the poppler library, and other 
information are here:

   https://bugs.launchpad.net/inkscape-devlibs/+bug/1552913

If one of the mingw developers can please look at this it would be a 
huge help.  Pretty sure you are going to need a debug version of the C 
libraries to sort this out.  It looks like stepping into the printf() 
functions is the way to go, but I cannot do that in the mingw 
development environment I use.

Thank you,

David Mathog
mathog@xxxxxxxxxxx
Manager, Sequence Analysis Facility, Biology Division, Caltech

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