Method has_value

external/parallel_hashmap/phmap_base.h:2412–2412

optional::has_value() Determines whether the `optional` contains a value. Returns `false` if and only if `*this` is empty.

    // Determines whether the `optional` contains a value. Returns `false` if and
    // only if `*this` is empty.
    constexpr bool has_value() const noexcept { return this->engaged_; }

// Suppress bogus warning on MSVC: MSVC complains call to reference() after
// throw_bad_optional_access() is unreachable.