[clang-tools-extra] [clang-tidy] Create bugprone-incorrect-enable-shared-from-this check (PR #102299)

[via cfe-commits]

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+.. title:: clang-tidy - bugprone-incorrect-enable-shared-from-this
+
+bugprone-incorrect-enable-shared-from-this
+==========================================
+
+Checks if a class or struct publicly inherits from 
+``std::enable_shared_from_this``, because unintended behavior will 
+otherwise occur when calling ``shared_from_this``.
+
+Consider the following code:
+
+.. code-block:: c++
+
+    #include <memory>
+
+    // private inheritance
+    class BadExample : std::enable_shared_from_this<BadExample> {
+    
+    // ``shared_from_this``` unintended behaviour
+    // libstd implementation returns uninitialized ``weak_ptr``
+        public:
+        BadExample* foo() { return shared_from_this().get(); }
+        void bar() { return; }
+    };
+
+    void using_not_public() {
+        auto bad_example = std::make_shared<BadExample>();
+        auto* b_ex = bad_example->foo();
+        b_ex->bar();
+    }
+
+Using ``libstd`` implementation, ``shared_from_this`` will throw 
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MichelleCDjunaidi wrote:

Yeah, libstdc++. Will change.

https://github.com/llvm/llvm-project/pull/102299