On 29/03/21 14:49 -0400, Patrick Palka via Libstdc++ wrote:
The <ranges> header currently copies some simple algorithms from <bits/ranges_algo.h>, which was originally done in order to avoid a circular dependency with the header. This is no longer an issue since the latter header now includes <bits/ranges_util.h> instead of all of <ranges>.This means we could now just include <bits/ranges_algo.h> and remove the copied algorithms, but that would double the size of <ranges>. And we can't use the corresponding STL-style algorithms here because they assume input iterators are copyable. So this patch instead simplifies these copied algorithms, removing their constraints and unused parameters, and keeps them around. In a subsequent patch we're going to copy ranges::find into <ranges> as well. libstdc++-v3/ChangeLog: * include/std/ranges (__detail::find_if): Simplify. (__detail::find_if_not): Likewise. (__detail::min): Remove. (__detail::mismatch): Simplify. (take_view::size): Use std::min instead of __detail::min.
I wonder if we want a <bits/ranges_algobase.h> which has this subset of algos. That could be used from <ranges> and also from the real algos in <bits/ranges_algo.h>. The ones in ranges_algobase.h wouldn't need to have the constraints (because we know the caller is constrained, or uses them correctly), but for that to work the unused params would need to be re-added. We can consider that for GCC 12 though. So OK for GCC 11.
