[libcxx-commits] [PATCH] D115422: [libc++][ranges] Add subsumption tests to `[special.mem.concepts]`.

[Arthur O'Dwyer via Phabricator via libcxx-commits]

Quuxplusone requested changes to this revision.
Quuxplusone added inline comments.
This revision now requires changes to proceed.


================
Comment at: libcxx/test/libcxx/algorithms/specialized.algorithms/special.mem.concepts/nothrow_forward_range.compile.pass.cpp:38-42
+constexpr bool forward_subsumes_input(std::ranges::__nothrow_forward_range auto)
+  requires true {
+  return true;
+}
+constexpr bool forward_subsumes_input(std::ranges::__nothrow_input_range auto);
----------------
Quuxplusone wrote:
> Here, `requires true` is unnecessary: the former should //properly subsume// the latter, in the sense of "proper subset".
> 
> Also, I think it is actually //more// important (so I'd like to see) that you test "nothrow-sentinel-for and sentinel_for subsume each other." In that case, since the subsumption is not proper, the `requires true` will be needed in order to make the one function more-constrained than the other.
Oh, and also, please always pass [iterator types by value, but] range types by forwarding reference:
```
constexpr bool forward_subsumes_input(std::ranges::__nothrow_input_range auto&&);
```
Then you can use `"foo"` as your forwarding range here, too, instead of dragging in a `std::array` dependency.


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115422/new/

https://reviews.llvm.org/D115422