I thought I'd found the right function: std::filesystem::path::concat to do something like
auto b = path(C:a/b);
const auto c = b.concat(/c);
c has the right value, but b is mutated (it ultimately equals c).
I want b to remain unaffected. According to the documentation, concat is equivalent to operator+=. However, there's no operator+.
I think is a weird design, because there's the similar operator/= and operator/ where / means subdirectory instead of literal concat (like +=).
Can I do this non-mutating concat without something like const auto c = std::filesystem::path(b.string() + "/c")?