3 ms·

Why not just define these things? Make -fwrapv, -fno-strict-aliasing the standard?

• gpderetta 8y ago
  Because many (most?) Don't want them.
  • twtw 8y ago
    Any specific examples? I know Linux, at least, uses these flags to compile, and Linus scorns these parts of the standard.
    • vyodaiken 8y ago
      There is no practical use for those UB "optimizations".
• garaetjjte 8y ago
  Because it prevents some optimizations, eg. there is one reason for signed overflow UB: https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7 https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759...
• vinkelhake 8y ago
  One argument (that is unrelated to optimization) for keeping signed wrap undefined is that most instances of it is a real bug. By keep signed wrap undefined, you now have the option of using -ftrapv to weed out such bugs.
  • jforberg 8y ago
    That might be a valid argument for making -ftrapv the standard. It's certainly not an argument for keeping it undefined. Most -f options tweak the standard in some way and defining overflow would not make -ftrapv suddenly go away.