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PODebugging a crash that does not happen inside a debugger
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copied!<p>I split a monolithic piece of code into dynamically loaded library and <code>main()</code> that calls it. I use no other library than stdc++, nor are there any classes, just a templated struct that has no member functions. I am not allocating any memory explicitly nor deleting or freeing anything in the code. I do use erase objects from a <code>list<T></code>.</p> <p>After the switch to library + main I am getting intermittent crashes.</p> <p><code>*** glibc detected *** : free(): invalid pointer:</code></p> <p>From the backtrace it seems a list itertor is involved, but the name mangled symbols make it hard to be sure.</p> <p>However it does not crash inside gdb, nor does valgrind detect any memory corruption or leaks.</p> <p>I have not build shared libraries before. This is what I am using</p> <p><code>g++ -fPIC -shared library_src.cpp -o libblaH.so</code></p> <p><code>g++ main.cpp -lblaH</code></p> <p>The entirety of the library is in a single source file, the library function is wrapped in an <code>extern "C"</code> block to make it accessible to c users, but right now i am compiling main() with g++ as a c++ code.</p> <p>Now when I add optimization options, <code>-O2</code> (in particular) I start getting the crashes.</p> <p>I have tried <code>electricfence</code> it says the invalid pointer was not allocated by malloc.</p> <p>I would appreciate suggestions on how to hunt the bug down. My feeling is that I am invalidation a list iterator somewhere, but how I am not sure. I thought they cant be invalidated, except for deleted entries.</p>

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