[libcxx-commits] [libcxx] [libcxx][string] Test: default constructed allocators can be unequal (PR #195839)

[Louis Dionne via libcxx-commits]

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@@ -515,4 +515,40 @@ struct SocccAllocator {
   using propagate_on_container_swap            = std::false_type;
 };
 
+// Track how many times the allocator was default-constructed
+//
+
+template <class T>
+class ControlledDefaultConstructorAllocator : public std::allocator<T> {
+public:
+  template <class U>
+  struct rebind {
+    typedef ControlledDefaultConstructorAllocator<U> other;
+  };
+
+  ControlledDefaultConstructorAllocator() TEST_NOEXCEPT { default_constructed_tag_ = next_default_constructed_tag_++; }
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ldionne wrote:

I'm not certain it's actually useful to increment the value? We're not trying to test that an allocator is default constructed only once, we're trying to ensure that a default-constructed allocator is used, period.

https://github.com/llvm/llvm-project/pull/195839