## Summary
* Partial #17238
* Flyby from discord discussion - `todo_type!` now statically checks for
no parens in the message to avoid issues between debug & release build
tests
## Test Plan
many mdtests are changing
Just like in #15045 for unary expressions: In binary expressions, we
were only looking for dunder expressions for `Type::Instance` types. We
had some special cases for coercing the various `Literal` types into
their corresponding `Instance` types before doing the lookup. But we can
side-step all of that by using the existing `Type::to_meta_type` and
`Type::to_instance` methods.
We have a handy `to_meta_type` that does the right thing for class
instances, and also works for all of the other types that are “instances
of” something. Unless I'm missing something, this should let us get rid
of the catch-all clause in one fell swoop.
cf #14548
