Use std::less<> for Labels to enable heterogeneous lookup on C++14+

[aeroyorch]

No description provided.

[gjasny]

Hello,

do you have a benchmark that shows improvements with this change? I'm a little bit hesitant to make the public ABI dependent on __cpp_lib_generic_associative_lookup. If the change is worth it, I'd raise the required C++ standard to 14 (or newer).

But most of the comparisons happen with Labels and thus with std::string.

Thanks,
Gregor

[aeroyorch]

Hello,

do you have a benchmark that shows improvements with this change? I'm a little bit hesitant to make the public ABI dependent on __cpp_lib_generic_associative_lookup. If the change is worth it, I'd raise the required C++ standard to 14 (or newer).

But most of the comparisons happen with Labels and thus with std::string.

Thanks,
Gregor

Ok, I'll try to put together a benchmark next week. I don't expect a big improvement inside the library itself, but it could help users who use the Labels alias directly, especially when doing lookups with std::string_view or string literals.