[clang-tools-extra] [clang-tidy] Added bugprone-exception-rethrow check (PR #86448)

[via cfe-commits]

================
@@ -0,0 +1,67 @@
+.. title:: clang-tidy - bugprone-exception-rethrow
+
+bugprone-exception-rethrow
+==========================
+
+Identifies problematic exception rethrowing, especially with caught exception
+variables or empty throw statements outside catch blocks.
+
+In C++ exception handling, a common pitfall occurs when developers rethrow
+caught exceptions within catch blocks by directly passing the caught exception
+variable to the ``throw`` statement. While this approach can propagate
+exceptions to higher levels of the program, it often leads to code that is less
+clear and more error-prone. Rethrowing caught exceptions with the same exception
+object within catch blocks can obscure the original context of the exception and
+make it challenging to trace program flow. Additionally, this method can
+introduce issues such as exception object slicing and performance overhead due
+to the invocation of the copy constructor.
+
+.. code-block:: c++
+
+  try {
+    // Code that may throw an exception
+  } catch (const std::exception& e) {
+    throw e; // Bad
+  }
+
----------------
isuckatcs wrote:

I think showing an example of exception object slicing would also be benefical if we mention it as an example, so how about presenting the examples like this:

```suggestion
introduce issues such as exception object slicing and performance overhead due
to the invocation of the copy constructor.

.. code-block:: c++

  try {
    // Code that may throw an exception
  } catch (const std::exception& e) {
    throw e; // Bad, 'e' is copied
  }

.. code-block:: c++
  class derived_exception : public std::exception { ... };

  void throwDerived() { throw derived_exception{}; }

  try {
    throwDerived();
  } catch (const std::exception& e) {
    throw e; // Bad, exception slicing occurs as 'derived_exception' is rethrown as 'exception' (maybe with better wording ?) 
  }


```

https://github.com/llvm/llvm-project/pull/86448