main.cpp2:6:38: error: variable 'require' declared with deduced type 'std::optional' cannot appear in its own initializer
6 | std::optional require {CPP2_UFCS_0(require, t)};
| ^
main.cpp2:6:17: error: no viable constructor or deduction guide for deduction of template arguments of 'optional'
6 | std::optional require {CPP2_UFCS_0(require, t)};
| ^
See https://github.com/hsutter/cppfront/issues/550#issuecomment-1834594548: