rspec/rules/S6427/cfamily/rule.adoc

== Why is this an issue?

The class `std::optional` stores an optional value: a `std::optional<T>` can either contain a value of type `T` or be empty. One way to access the value of a non-empty optional is the `operator*`, making an optional look like a pointer.

However, the similarity ends there. In particular, the preferred way to assign a value to an optional is to assign it directly (as opposed to assigning it to the dereferenced value or to the result of the function `value()`). In that case, the assignment works even if the optional does not have a prior value. 

=== Noncompliant code example

[source,cpp]
----
void g(std::optional<int> &val, bool b) {
    if (b) {
      *val = 314; // Noncompliant, will throw if the optional was previously empty
    } else {
      val.value() = 42; // Noncompliant, will throw if the optional was previously empty
    }
}
----

=== Compliant solution

[source,cpp]
----
void g(std::optional<int> &val, bool b) {
    if (b) {
      val = 314; // Compliant
    } else {
      val = 42; // Compliant
    }
}
----