I don't remember the details, roughly it was unexpected invocation of move semantic, causing use after free in a loop.
My all-time favourite example is (again, my memory, I may be a bit wrong):
for (int i = 0; i < (size_t)limit; ++i) {
}
at some point limit could potentially become greater than INT_MAX, the compiler decided that i<limit could never be true because that would cause signed int overflow which is UB, so it "optimized" the loop into
alt Hacker News
I don't remember the details, roughly it was unexpected invocation of move semantic, causing use after free in a loop.
My all-time favourite example is (again, my memory, I may be a bit wrong):
at some point limit could potentially become greater than INT_MAX, the compiler decided that i<limit could never be true because that would cause signed int overflow which is UB, so it "optimized" the loop into signed unsigned mismatch makes me shiver