[libc-commits] [libc] [libc] Fix casts for arm32 after Wconversion (PR #129771)

[Michael Jones via libc-commits]

michaelrj-google wrote:

It's not that `array` handles negatives, it's that the `at` lambda is only used in `safe_get_at`, and the `safe_get_at` function does the bounds checking:
```
  const auto safe_get_at = [&](size_t index) -> word {
    // return appropriate value when accessing out of bound elements.
    const int i = at(index);
    if (i < 0)
      return 0;
    if (i >= int(N))
      return is_neg ? cpp::numeric_limits<word>::max() : 0;
    return array[i];
  };
```
If `i` is negative or greater than the size of the size of the array, it returns before it attempts to index into `array`.

https://github.com/llvm/llvm-project/pull/129771