Add std::hash specialization

nholthaus / units

a compile-time, header-only, dimensional analysis and unit conversion library built on c++14 with no dependencies.

http://nholthaus.github.io/units/

MIT License

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Closed JohelEGP closed 6 years ago

JohelEGP commented 6 years ago

Makes the units hashable. I took the liberty of making it constexpr rather than not and using the std::hash of the underlying type.

Drive-by fix: remove CompileTimeArithmetic test ?scope? I think it predates constexpr units.