Boost. 1.91.0 regression: optional<bool> copy constructor broken

[MarcelRaad]

Consider the following code:

const boost::optional<bool> constValue;
assert(!constValue.has_value()); // succeeds
boost::optional<bool> mutableValue(constValue);
assert(!mutableValue.has_value()); // succeeds
boost::optional<bool> mutableCopy(mutableValue);
assert(!mutableCopy.has_value()); // fails

The reason is that the wrong constructor is taken for boost::optional(boost::optional&):

optional/include/boost/optional/detail/union_optional.hpp

Line 391 in 88e2378

template <typename U,

instead of

optional/include/boost/optional/detail/union_optional.hpp

Line 293 in 88e2378

constexpr optional(const optional& rhs)

.