Quick question: This proposal adds a Runtime module. Do we think this would also be an appropriate module name for the demangle APIs that were proposed in SE-0262?
One of the reasons that proposal was returned for revision was that we felt its APIs were too niche for the standard library and ought to be in a more specialized module. Now that we're adding such a module, we should make sure it has a name that would be suitable for the demangle functions as well.
(To be clear, I'm not suggesting that we increase the scope of this proposal to include demangling—just that we should think about whether we're doing something that would work for it.)