[libcxx-commits] [libcxx] [libc++] Add a release note about multi{map, set}::find not returning the first element anymore (PR #155252)

[Louis Dionne via libcxx-commits]

================
@@ -61,6 +61,10 @@ Deprecations and Removals
 Potentially breaking changes
 ----------------------------
 
+- The algorithm for ``multi{map,set}::find`` has been modified, which doesn't guarantee that the first element is
+  returned. If code relies on the first element being returned from ``find`` it may be broken. To fix it use
+  ``lower_bound`` or ``equal_range`` instead.
----------------
ldionne wrote:

```suggestion
- The algorithm for ``multi{map,set}::find`` has been modified such that it doesn't necessarily return an iterator to the first equal element in the container. This was never guaranteed by the Standard, but libc++ previously happened to always return the first equal element, like other implementations do. Starting with this release, code relying on the first element being returned from ``find`` will be broken, and ``lower_bound`` or ``equal_range`` should be used instead.
```

https://github.com/llvm/llvm-project/pull/155252