Check value is in range before casting from double to uint32_t

[kevinbackhouse]

Fixes: #1827

The static_cast<long> can cause a UBSAN failure if the value of tmp is out of range. It was also incorrect to cast to long, because the type of ur.second is uint32_t.

[kevinbackhouse]

I wonder if we should use nearbyint for the rounding on the main branch. (Can't use it on 0.27-maintenance because it's a C++11 feature.) C++11 also has an lround function, but it doesn't seem to be any better at handling out-of-range values, and it's return type is long which isn't platform independent.

[lgtm-com]

This pull request introduces 1 alert when merging 1455cc8 into b364b1d - view on LGTM.com

new alerts:

• 1 for Comparison result is always the same

[hassec]

👍 for using C++11 features in main.

Any reason to use nearbyint over just std::round? std::round would give use the rounding behavior we have implemented right now, while nearbyint would depend on the rounding mode that is set

[kevinbackhouse]

@hassec: you're right, std::round is better than std::nearbyint. I overlooked it when I was reading about std::lround!