"Doug Gregor" <[EMAIL PROTECTED]> writes: [...]
| > | For instance, say we have built the types T* and | > | U* before seeing that same-type constraint. Now, we also need | > | TYPE_CANONICAL (T*) == TYPE_CANONICAL (U*). | > | And TYPE_CANONICAL(LessThanComparable<T>) == | > | TYPE_CANONICAL(LessThanComparable<U>). | > | If you know about all of these other types that have been built from T | > | and U, you can use Nelson and Oppen's algorithm to update the | > | TYPE_CANONICAL information relatively quickly. If you don't have that | > | information... | > | > In a template definition, one has that information. | | ? | | Our same-type constraint says SameType<T, U>. | | We can easily set TYPE_CANONICAL for T and U. | | We also need to set the TYPE_CANONICAL fields of LessThanComparable<T> | and LessThanComparable<U> to the same value. | | How do we get from 'T' to 'LessThanComparable<T>'? Delay semantics processing (that is canonical types, etc.) until you have build all of the constraint set -- that is basically what we do for C++98 and C++03 templates. At the end of the definition declaration, you have enough needed to unify the canonical type nodes for T*, U*, LessThanComparable<T>, etc. In a sense that is very similar to what we do for definitions that appear lexically in class definitions. -- Gaby
