[libcxx-commits] [libcxx] [libc++] Do not call `reserve` in flat containers if underlying container is user defined (PR #140379)

[Louis Dionne via libcxx-commits]

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@@ -36,6 +36,8 @@ struct __container_traits {
   // `insert(...)` or `emplace(...)` has strong exception guarantee, that is, if the function
   // exits via an exception, the original container is unaffected
   static _LIBCPP_CONSTEXPR const bool __emplacement_has_strong_exception_safety_guarantee = false;
+
+  static _LIBCPP_CONSTEXPR const bool __reservable = false;
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ldionne wrote:

Could you please add a bit of documentation for this new property?

https://github.com/llvm/llvm-project/pull/140379