...by giving all the types silly magic-themed names, rather than just
'Base' or 'SomeProto'. That makes a (mostly) consistent theme throughout
the document, and hopefully makes it easier to have a mental model
about what various changes mean.
This will be used to help IRGen record protocol requirements
with resilient default implementations in protocol metadata.
To enable testing before all the Sema support is in place, this
patch adds SIL parser, printer and verifier support for default
witness tables.
For now, SILGen emits empty default witness tables for protocol
declarations in resilient modules, and IRGen ignores them when
emitting protocol metadata.
I realized "members are mostly the same as their top-level equivalents" is worth
calling out explicitly, especially for subscripts and initializers without top-level
equivalents. There's still a hole here for members of protocol extensions, which can
have pretty drastic effects on conforming types.
"Proposal" refers to something going through the Swift Evolution Process,
which this won't as such. (Although it does have many pieces affected by
proposals, as described at the end of the document.)
Basically, elaborate on why it's not important right now. Also, drop the
section on limiting the addition of new vtable-dispatched methods. That's
not something we're really interested in.
The Default Behavior Should Be Safe
Also, remove the line about "providing tools to check changes", because
it no longer fits in the prologue flow and isn't core to the model.
The section on it is good enough.
I went through the list of attributes and declaration modifiers and
made sure they were all accounted for. Anything not on the list
should be assumed restricted, as mentioned at the top of the
"Supported Evolution" section.
- Implement emission of type references for nominal type field
reflection, using a small custom encoder resulting in packed
structs, not strings. This will let us embed 7-bit encoded
32-bit relative offsets directly in the structure (not yet
hooked in).
- Use the AST Mangler for encoding type references
Archetypes and internal references were complicating this before, so we
can take the opportunity to reuse this machinery and avoid unique code
and new ABI.
Next up: Tests for reading the reflection sections and converting the
demangle tree into a tree of type references.
Todo: For concrete types, serialize the types for associated types of
their conformances to bootstrap the typeref substitution process.
rdar://problem/15617914
...most of which don't exist yet. These are things that need to go
through the Swift Evolution Process and ultimately be accepted or
rejected before we have final answers on some parts of the document.
As part of SE-0022, introduce an 'objc_selector' encoding for string
literals that places the UTF-8 string literal into the appropriate
segment for uniquing of Objective-C selector names.
Specifically, public members (and nested types) within a versioned type are
assumed to be present on the outer type since its introduction unless otherwise
specified. (This saves boilerplate for a type's initial API.)
Instead of directly emitting calls to swift_getGenericMetadata*() and
referencing metadata templates, call a metadata accessor function
corresponding to the UnboundGenericType of the NominalTypeDecl.
The body of this accessor forwards arguments to a runtime metadata
instantiation function, together with the template.
Also, move some code around, so that metadata accesses which are
only done as part of the body of a metadata accessor function are
handled separately in emitTypeMetadataAccessFunction().
Apart from protocol conformances, this means metadata templates are
no longer referenced from outside the module where they were defined.
This drops the requirement that a fixed-layout struct only contain fixed-size
things (which wasn't specified correctly anyway). Slava and Dmitri both
pointed out that the previous definition had several flaws, including not
really scaling to generics. This reduced version only promises that stored
instance properties won't be added, removed, or modified, which is still
enough to do useful optimizations. And in most cases, we'll be able to
infer the full "fixed-size" property of a type from this attribute anyway.
The name "fixed-contents" was chosen to force us to pick a better name later.
The next commit will bring back the "fixed-size" property as a performance
assertion.
Now that we've decided to allow using versioned internal types in
fixed-layout structs, this isn't just about inlineable functions anymore.
No content change.
Fixes:
* multiple statements on one line (colon) (E701)
* missing whitespace around arithmetic operator (E226)
* missing whitespace around operator (E225)
* closing bracket does not match visual indentation (E124)
* blank line contains whitespace (W293)
* continuation line missing indentation or outdented (E122)
* continuation line over-indented for hanging indent (E126)
* missing expected blank line (E301)
* trailing whitespace (W291)
* unexpected spaces around keyword / parameter equals (E251)
* whitespace after '(', '[' or '{' (E201)
* whitespace before ')', ']' or '}' (E202)
* whitespace before ',' or ':' (E203)
...as Slava pointed out, many times it means "versioned". I chose to
leave several things as "non-public, non-versioned" even though "non-
versioned" is sufficient (a versioned library may not have unversioned
public API) because "non-public" is something people instinctively
understand.
