Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
- Add a `[reflection]` bit to `alloc_box` instructions, to indicate that a box
should be allocated with reflection metadata attached.
- Add a `@captures_generics` attribute to SILLayouts, to indicate a type layout
that captures the generic arguments it's substituted with, meaning it can
recreate the generic environment without additional ABI-level arguments, like
a generic partial application can.
Except GenericEnvironment.h, because you can't meaningfully use a
GenericEnvironment without its signature. Lots less depends on
GenericSignature.h now. NFC
Use a syntax that declares the layout's generic parameters and fields,
followed by the generic arguments to apply to the layout:
{ var Int, let String } // A concrete box layout with a mutable Int
// and immutable String field
<T, U> { var T, let U } <Int, String> // A generic box layout,
// applied to Int and String
// arguments
Trying to contain it in SIL doesn't really work if we want to be able to print or parse SIL box types, since the type parser and printer doesn't otherwise depend on the SIL module.
