[libcxx-commits] [libcxx] [libc++] Remove UB from std::map __tree_node constructor (PR #153908)

[via libcxx-commits]

github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {clang-format}-->


:warning: C/C++ code formatter, clang-format found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
git-clang-format --diff HEAD~1 HEAD --extensions  -- libcxx/include/__tree
``````````

</details>

<details>
<summary>
View the diff from clang-format here.
</summary>

``````````diff
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
index d860f4c96..5245dcdb2 100644
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -582,25 +582,25 @@ class _LIBCPP_STANDALONE_DEBUG __tree_node : public __tree_node_base<_VoidPtr> {
 public:
   using __node_value_type _LIBCPP_NODEBUG = __get_node_value_type_t<_Tp>;
 
-  // We allow starting the lifetime of nodes without initializing the value held by the node,
-  // since that is handled by the map itself in order to be allocator-aware.
-  #  ifndef _LIBCPP_CXX03_LANG
+// We allow starting the lifetime of nodes without initializing the value held by the node,
+// since that is handled by the map itself in order to be allocator-aware.
+#ifndef _LIBCPP_CXX03_LANG
 
-  private:
-    union {
-      __node_value_type __value_;
-    };
+private:
+  union {
+    __node_value_type __value_;
+  };
 
-  public:
-    _LIBCPP_HIDE_FROM_ABI __node_value_type& __get_value() { return __value_; }
-  #  else
+public:
+  _LIBCPP_HIDE_FROM_ABI __node_value_type& __get_value() { return __value_; }
+#else
 
-  private:
-    _ALIGNAS_TYPE(__node_value_type) unsigned char __buffer_[sizeof(__node_value_type)];
+private:
+  _ALIGNAS_TYPE(__node_value_type) unsigned char __buffer_[sizeof(__node_value_type)];
 
-  public:
-    _LIBCPP_HIDE_FROM_ABI __node_value_type& __get_value() { return *std::__launder(reinterpret_cast<_Tp*>(&__buffer_)); }
-  #  endif
+public:
+  _LIBCPP_HIDE_FROM_ABI __node_value_type& __get_value() { return *std::__launder(reinterpret_cast<_Tp*>(&__buffer_)); }
+#endif
 
   template <class _Alloc, class... _Args>
   explicit __tree_node(_Alloc& __na, _Args&&... __args) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/153908