bool std::uncaught_exception() allows you to know whether a thread is in an exception stack unwinding context. However, its practical
functionality was restricted.
C++17 deprecates bool std::uncaught_exception() and introduces int std::uncaught_exceptions() which returns the number of
uncaught exceptions. The code example below shows how you can benefit from this new improved function.
std::uncaught_exception has been removed in C++20.
This rule will flag any usage of std::uncaught_exception.
Noncompliant code example
class Transaction {
// ...
~Transaction() {
if (!std::uncaught_exception()) { // Noncompliant, replace std::uncaught_exception by std::uncaught_exceptions
// commit
} else {
// rollback
}
}
};
Compliant solution
The following example shows how std::uncaught_exceptions can be used to determine in ~Transaction if a new exception was
thrown since t1/t2 creation.
class Transaction {
// ...
~Transaction() {
if (initialUncaughtExceptions == std::uncaught_exceptions()) {
// commit
} else {
// rollback
}
}
// ...
int initialUncaughtExceptions = std::uncaught_exceptions();
};
int f() {
try {
Transaction t1;
// ... something here could throw
} catch(...) {
Transaction t2;
// ... something here could throw
}
}
