What are the implications of a lower level compilation?
Would a gdb trace with dev versions of libraries (incl. QT) and the binary not provide more detail?
==1875== Invalid read of size 1 ==1875== at 0x5697098: QString::fromLatin1_helper(char const*, int) (in /usr/lib/libQtCore.so.4.7.4) ==1875== Address 0x73 is not stack'd, malloc'd or (recently) free'd