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

[via cfe-commits]

================
@@ -0,0 +1,103 @@
+// RUN: %check_clang_tidy %s bugprone-exception-rethrow %t -- -- -fexceptions
+
+struct exception {};
+
+namespace std {
+  template <class T>
+  T&& move(T &&x) {
+    return static_cast<T&&>(x);
+  }
+}
+
+void correct() {
+  try {
+      throw exception();
+  } catch(const exception &) {
+      throw;
+  }
+}
+
+void correct2() {
+  try {
+      throw exception();
+  } catch(const exception &e) {
+      try {
+        throw exception();
+      } catch(...) {}
+  }
+}
+
+void not_correct() {
+  try {
+      throw exception();
+  } catch(const exception &e) {
+      throw e;
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught 'exception' exception, remove the argument to throw the original exception object [bugprone-exception-rethrow]
+  }
+}
+
+void not_correct2() {
+  try {
+      throw exception();
+  } catch(const exception &e) {
+      throw (e);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught 'exception' exception, remove the argument to throw the original exception object [bugprone-exception-rethrow]
+  }
+}
+
+void not_correct3() {
+  try {
+      throw exception();
+  } catch(const exception &e) {
+      throw exception(e);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught 'exception' exception, remove the argument to throw the original exception object [bugprone-exception-rethrow]
+  }
+}
+
+void not_correct4() {
+  try {
+      throw exception();
+  } catch(exception &e) {
+      throw std::move(e);
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught 'exception' exception, remove the argument to throw the original exception object [bugprone-exception-rethrow]
+  }
+}
+
+void not_correct5() {
+  try {
+      throw 5;
+  } catch(const int &e) {
+      throw e;
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: throwing a copy of the caught 'int' exception, remove the argument to throw the original exception object [bugprone-exception-rethrow]
+  }
+}
+
+void rethrow_not_correct() {
+  throw;
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: empty 'throw' outside a catch block with no operand triggers 'std::terminate()' [bugprone-exception-rethrow]
+}
+
+void rethrow_not_correct2() {
+  try {
+    throw;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: empty 'throw' outside a catch block with no operand triggers 'std::terminate()' [bugprone-exception-rethrow]
+  } catch(...) {
+  }
+}
+
+void rethrow_correct() {
+  try {
+    throw 5;
+  } catch(...) {
+    throw;
+  }
+}
+
+void rethrow_in_lambda() {
+  try {
+    throw 5;
+  } catch(...) {
+    auto lambda = [] { throw; };
+// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: empty 'throw' outside a catch block with no operand triggers 'std::terminate()' [bugprone-exception-rethrow]
----------------
isuckatcs wrote:

At this point this is still a false positive. Maybe in the end we should just consider ignoring `throw` statements inside functions and lambdas. Dropping coverage to prevent false-positives is fine I think.

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