-fPIC changes sizeof class

Alan M. Carroll amc@network-geographics.com
Fri Aug 7 17:03:00 GMT 2009

I have chased down a crash in my code to -fPIC changing the size of a class. My overall project uses some static libraries which are compiled without -fPIC and some dynamic libraries that use -fPIC. The effect is that if I use a template class in a static library and a dynamic library that links to the static library, I have to compile the static library with -fPIC as well. According to the documentation[1] this flag shouldn't have any effect at all because I am building for 64 bit Intel.

My question is, is this expected behavior? Or should I try to get a smaller example that demonstrates the problem?

gcc 4.3.3, x86-64, Fedora Core 10. The class and its members both have a lot of inherited zero-size classes.

[1] http://gcc.gnu.org/onlinedocs/gcc-4.3.3/gcc/Code-Gen-Options.html#Code-Gen-Options

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