database.path() returns std::string const& to reduce friction

[oldnewthing]

This reduces friction with the std::set<std::string> returned by reader.files(),

[DefaultRyan]

My first instinct was to resolve this friction by making the std::set's comparator transparent to allow it to operate with std::string_view.

  std::set<std::string, std::less<>> s; // std::less<> deduces parameter types
  auto iter = s.find(std::string_view{"asdf"});

[oldnewthing]

My first instinct was to resolve this friction by making the std::set's comparator transparent to allow it to operate with std::string_view.
std::set<std::string, std::less<>> s; // std::less<> deduces parameter types
auto iter = s.find(std::string_view{"asdf"});

I thought about that, but suspected (perhaps erroneously) that transparency would result in a std::string being created at every node comparison inside std::set<>::find().

Even if transparency worked, that would create friction between reader.files() and anybody else who wants to use std::set<std::string>, because std::set<std::string> and a std::set<std::string, std::less<>> would not be compatible.