`A15-4-4`: Query incorrectly alerts functions that raise/can raise exceptions

[rak3-sh]

Affected rules

A15-4-4

Description

1. Query doesn’t consider ReThrowExpr. E.g. the query says to mark rethrow() below as noexcept

Example

template <bool DoRethrow>
void rethrow() {
  throw;
}

int main()
{
  rethrow<true>();
  return 0;
}

2. The query doesn’t check for throw expressions that occur inside lambdas defined in a function. E.g.

Example

void func()  {
    std::call_once(init_flag_, [this] {
      if (sem_init(&sem_, 0, 0) != 0) {
        throw std::system_error(errno, std::system_category()); // Throw in a lambda.
      }
      initialized_ = true;
    });
  }

3. In some cases the noexcept specification is a complex condition involving several logical operations or template instantiations. In such a case, CodeQL’s check for whether its noexcept(true) or noexcept explicitly false doesn’t work and it alerts that it can be marked as noexcept. For practical reasons, maybe we can consider a noexcept(expr) as being marked by the user as correct.