Non-exception types should not be caught

Throwing as an exception an object that is not derived from std::exception is a bad practice. It is usually unreliable, meaningless, and a source of type clashes.

For the same reason, catching a non-exception type is a sign that your application has a bad exception-handling design. You should use standard exception types or create your own exception types that inherit at some level from std::exception.

Noncompliant Code Example

try {
  /* code that can throw: 42 */
} catch (int ex) { // Noncompliant
  if (ex == 42) {
    /*...*/
  }
}

Compliant Solution

try {
  /* code that can throw: std::domain_error("User ID not found.") */
} catch (const std::domain_error& ex) {
  /*...*/
}

See

• C++ Core Guidelines E.14 - Use purpose-designed user-defined types as exceptions (not built-in types)