Hi Giuseppe, std-proposals,
I just noticed today that P2248 "Enabling list-initialization for algorithms" still fails to enable this very common use-case of mine:
std::vector<int> v = {1,2,3,4,5};
assert(std::ranges::equal(v, {1,2,3,4,5}));
Was this possibility ever discussed before?
This could be handled by defaulting the `R2` parameter to `initializer_list`, but it probably makes more sense to add a whole new overload of `std::equal`, as follows. (This means it's quite reasonable that P2248 wouldn't have proposed this idea... but I'm still wondering if it's been discussed before.)
// the existing overload
template<ranges::input_range R1, ranges::input_range R2, class Pred = ranges::equal_to,
class Proj1 = std::identity, class Proj2 = std::identity>
requires std::indirectly_comparable<ranges::iterator_t<R1>, ranges::iterator_t<R2>,
Pred, Proj1, Proj2>
constexpr bool equal( R1&& r1, R2&& r2, Pred pred = {},
Proj1 proj1 = {}, Proj2 proj2 = {} );
// the new overload
template<ranges::input_range R1, class V2, class Pred = ranges::equal_to,
class Proj1 = std::identity, class Proj2 = std::identity>
requires std::indirectly_comparable<ranges::iterator_t<R1>, const V2*,
Pred, Proj1, Proj2>
constexpr bool equal( R1&& r1, std::initializer_list<V2> r2, Pred pred = {},
Proj1 proj1 = {}, Proj2 proj2 = {} );
–Arthur