constexpr absl::Duration operators

[bogdan-lab]

Why absl::Duration arithmetic operators are not constexpr?
For example, I find it a bit confusing that if I want to create some "complex" duration value at compile time, for better readability I need to do this:

constexpr Duration test = absl::Seconds(9*3600 + 34*60 + 17);

But I cannot do this:

constexpr Duration test = absl::Hours(9) + absl::Minutes(34) + absl::Seconds(17);