Gregory's Server@mdiluz Amazing. Really, this is perfectly logical if you think about it. It's safe to remove the while loop because it does not have any side effects, and it is also safe to remove the instructions following the while loop because the loop as written provably doesn't terminate.
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@beeoproblem @aeva @mdiluz The reasoning I've seen is:  @RAOF @beeoproblem @mdiluz if you're missing a main function other functions don't get promoted to main. I tested it out in godbolt earlier, what happens is the ret instruction in main gets optimized out, thus the program counter just advances to the next instruction in memory which is the other function. The entry points for main and the other function still exist. @RAOF @beeoproblem @mdiluz gcc and msvc both do what you'd expect. Clang and zig's c++ compiler both optimize away the loop and the return. @beeoproblem @aeva @mdiluz the return call from main() got optimised away and so the CPU doesn’t jump away, and keeps taking further instructions from the assembly, which are the body of unreachable() @AgreeableLandscape @aeva @mdiluz because of linking, the compiler doesn't know if the object will be linked. The function can be called from another object. @ekg @AgreeableLandscape @mdiluz this exactly. To Agreeable Landscape's concerns, if you mark "unreachable" as static (indicating it only exists for the translation unit), then clang removes it. It's not a big spooky zero day, this is just how linking works 🤷♀️ |
@aeva @mdiluz but where does the call to unreachable come from? Your logic only explains the loop being optimized out unless I'm missing something.