The relational operators for std::optional were using the wrong types
in the declval expressions used to constrain them. Instead of using
const lvalues they were using non-const rvalues, which meant that a type
might satisfy the constraints but then give an error when the function
body was instantiated.
libstdc++-v3/ChangeLog:
PR libstdc++/96269
* include/std/optional (operator==, operator!=, operator<)
(operator>, operator<=, operator>=): Fix types used in
SFINAE constraints.
* testsuite/20_util/optional/relops/96269.cc: New test.
cdd2d448d8