[libcxx-commits] [PATCH] D112836: [libc++] Transparent unordered_foo::count() should use __count_multi.

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

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  An `unordered_set` doesn't contain duplicates of the key_type, but it
  may contain "duplicates" in the less-granular equivalence relationship
  imposed by the transparent hasher/comparator on non-key_type objects.
  The new tests are copied from the existing tests for `set` and `map`.
  Thanks to Marshall Clow for highlighting this issue/use-case.

N.B.: I just copied the existing `count_transparent.pass.cpp` from `set`... but that gives us both Marshall's `count_transparent.pass.cpp` //and// Ruslan's `count.transparent.pass.cpp`. This is probably a terrible idea, so I'm open to suggestions for new test names.

It might also be a good idea for us to have a "neg test" proving that `m.insert({Tuple2{1,2}, 3})` does //not// use heterogeneous lookup — it deliberately converts `Tuple2` into `Tuple3` and then looks up the `Tuple3` according to the more granular equivalence relation.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D112836

Files:
  libcxx/include/unordered_map
  libcxx/include/unordered_set
  libcxx/test/std/containers/associative/map/map.ops/count_transparent.pass.cpp
  libcxx/test/std/containers/associative/map/map.ops/equal_range_transparent.pass.cpp
  libcxx/test/std/containers/associative/set/count_transparent.pass.cpp
  libcxx/test/std/containers/associative/set/equal_range_transparent.pass.cpp
  libcxx/test/std/containers/unord/unord.map/count_transparent.pass.cpp
  libcxx/test/std/containers/unord/unord.map/equal_range_transparent.pass.cpp
  libcxx/test/std/containers/unord/unord.set/count_transparent.pass.cpp
  libcxx/test/std/containers/unord/unord.set/equal_range_transparent.pass.cpp

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