3 ms·

Strict aliasing is the only item on your list that I could see leading someone to get upset with the optimizer. And, maaaaaaybe signed integer overflow. With s

Strict aliasing is the only item on your list that I could see leading someone to get upset with the optimizer. And, maaaaaaybe signed integer overflow. With strict aliasing, I don't think your examples are correct. They all involve typecasting pointers, but don't involve interacting with the original type later. So, memcpy uses a void* as char* and MyAllocator uses char* as MyType*, but in both cases they never go back and expect predictible new values in the original types. The rest are clearly taught in CS100 to be doorways to chaos. In particular, complaining that volatile doesn't get rid of the need for locks is just making noise. Might as well complain that auto doesn't get rid of the need for locks. They are both unrelated to threading.

Kristine1975 11y ago
>And, maaaaaaybe signed integer overflow. Overflow checking is sometimes done like this (where a is a signed integer): if (a + 100 < a) ... Of course this invokes undefined behavior, and some people get angry when compilers remove the check: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30475 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30475
- anttihaapala 11y ago
  And of course the code is wrong, because the behaviour is undefined - in 64-bit architectures it is very common to use 64-bit registers for `int` even if in memory `sizeof(int) == 4`; thus `int a = INT_MAX;`, `a + 100` could still be greater than `INT_MAX`.