[libcxx-commits] [libcxx] [libc++] Improves UB handling in ios_base destructor. (PR #76525)

[Louis Dionne via libcxx-commits]

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@@ -360,7 +360,50 @@ public:
   }
 
 protected:
-  _LIBCPP_HIDE_FROM_ABI ios_base() { // purposefully does no initialization
+  _LIBCPP_HIDE_FROM_ABI ios_base() : __loc_(nullptr) {
+    // purposefully does no initialization
+    //
+    // Except for the locale, this is a sentinel to avoid destroying
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ldionne wrote:

I would move this useful but large explanation to the test, and I would only explain that we use `__loc_(nullptr)` as a sentinel to know whether we want to actually run the destructor or not.

https://github.com/llvm/llvm-project/pull/76525