[libcxx-commits] [libcxx] [libc++] Opt `std::*set` out of map key extraction optimization (PR #220452)

[A. Jiang via libcxx-commits]

================
@@ -75,6 +76,15 @@ int main(int, char**) {
     assert(std::get<1>(res));
     assert(set.begin() == std::get<0>(res));
   }
+  { // Regression test for #220451
----------------
frederick-vs-ja wrote:

```suggestion
  { // Regression test for https://llvm.org/PR220451.
```

https://github.com/llvm/llvm-project/pull/220452