The constraints on transform and and_then can cause errors when checking satisfaction. The constraints that were present in R6 of the paper were moved for he final F8 revision, and so should have been included in the implementation. libstdc++-v3/ChangeLog: PR libstdc++/102863 * include/std/optional (optional::and_then, optional::transform): Remove requires-clause. * testsuite/20_util/optional/monadic/and_then.cc: Check overload resolution doesn't cause errors. * testsuite/20_util/optional/monadic/transform.cc: Likewise. Tested x86_64-linux. Committed to trunk.