Warning C26829

Empty optional 'variable' is unwrapped

Remarks

Unwrapping empty std::optional values is undefined behavior. Such operation is considered a security vulnerability as it can result in a crash, reading uninitialized memory, or other unexpected behavior. This check will attempt to find cases where a std::optional is known to be empty and unwrapped. You can also enable C26830, C26859, and C26860 for a stricter analysis.

Example

void f(std::optional<int> maybeEmpty)
{
    std::optional<int> empty;
    std::optional<int> nonEmpty{5};
    *nonEmpty = 42; // No warning
    *empty = 42; // warning: C26829
    if (!maybeEmpty)
        *maybeEmpty = 42; // warning: C26829
}

To solve this problem, make sure the code never unwraps an empty optional. Alternatively, use the value method and make sure you handle the std::bad_optional_access exception.