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I'd be happy to discuss an example, because right now the idea that smart pointers are opaque about destruction is unfortunately too abstract for me to give a h
by blub 9y ago
I'd be happy to discuss an example, because right now the idea that smart pointers are opaque about destruction is unfortunately too abstract for me to give a helpful reply to.
- pcwalton 9y agoConsider situations like this: https://stackoverflow.com/questions/17362673/temporary-lifetime-extension https://stackoverflow.com/questions/17362673/temporary-lifet... It's undefined behavior, despite not calling free anywhere. Replace with std::string and it could be use after free. In C, UAF wouldn't happen that silently for heap memory.
- blub 9y agoA similar example was posted by matthieu_m on Reddit a while back, but that's still not worse than C, even if it's an unfortunate gap in compiler diagnostics. From my POV compilers should warn that this code is potentially dangerous. My rule is: never return a reference or pointer from a function to something whose lifetime you don't have control of.
- pcwalton 9y agoIt's worse than C because you can't have UAF in C without explicitly calling free (or a function that transitively calls free). In C++ freeing is implicit.