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

[via cfe-commits]

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+.. 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
+  }
+
+To prevent these issues, it is advisable to utilize ``throw;`` statements to
+rethrow the original exception object for currently handled exceptions.
+
+.. code-block:: c++
+
+  try {
+    // Code that may throw an exception
+  } catch (const std::exception& e) {
+    throw; // Good
+  }
+
+However, when empty throw statement is used outside of a catch block, it
+will result in a call to ``std::terminate()``, which abruptly terminates the
+application. This behavior can lead to abnormal termination of the program and
+is often unintended. Such occurrences may indicate errors or oversights in the
+exception handling logic, and it is essential to avoid empty throw statements
+outside catch blocks to prevent unintended program termination.
+
+.. code-block:: c++
+
+  void foo() {
+    // std::terminate will be called because there is no exception to rethrow
+    throw;
+  }
+
+  int main() {
+    try {
+      foo();
+    } catch(...) {
+      return 1;
+    }
+    return 0;
+  }
+
+Above program will be terminated with:
+
+.. code-block:: text
+
+  terminate called without an active exception
+  Aborted (core dumped)
+
+
----------------
EugeneZelenko wrote:

Excessive newline.

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