4 ms·

Could you explain why in this hypothetical scenario a warning should be emitted for “for (int i = 0...)”?

• inetknght 8y ago
  Range-based for loops are far more idiomatic for modern C++: https://stackoverflow.com/a/15089298/1111557 https://stackoverflow.com/a/15089298/1111557
  • saagarjha 8y ago
    They're also not in the standard library. Not everyone can justify integrating Boost into their applications :(
    • Y_Y 8y ago
      You can certainly do this with just the standard library and no boost, for example using iota from <numeric>. https://en.cppreference.com/w/cpp/algorithm/iota https://en.cppreference.com/w/cpp/algorithm/iota
      • saagarjha 8y ago
        That’s not a generator, though. You need to allocate an extra container for this to fill, which is inconvenient.
  • bonzini 8y ago
    And underneath they compile to an int for loop and a pointer dereference, both of which can be undefined behavior.
• platinumrad 8y ago
  bonzini's hypothetical scenario was one where the compiler emitted a warning every single time it encountered undefined behavior. Assuming that a loop counter cannot overflow because signed integer overflow is undefined is one such instance and would fall under the "99% false positives" that they mention.
  • jlebar 8y ago
    But of course this way leads to madness, because then we'd also have to warn every time you do `x + 1` or `*ptr`, both of which can lead to UB (if x is a signed integer and the addition overflows, or if ptr is null).
  • 0db532a0 8y ago
    Thanks.