If the -enable-experimental-subclass-existentials staging flag
is on, resolveType() now allows protocol compositions to contain
class types. It also diagnoses if a composition has more than one
superclass requirement.
Also, change diagnostics that talked about 'protocol composition'
to 'protocol-constrained type'.
Since such types can now contain a superclass constraint, it's not
correct to call them protocol composition.
"Protocol-constrained type" isn't quite accurate either because
'Any' has no protocols, and 'AnyObject' will have no protocols but
a general class constraint; but those are edge cases which won't
come up in these diagnostics.
Also adds:
- Any is caught before doing an unconstrained lookup, and the
protocol<> type is emitted
- composition expressions can be handled by
`PreCheckExpression::simplifyTypeExpr` to so you can do lookups like (P
& Q).self
- Fixits corrected & new tests added
- Typeref lowering cases should have been optional
- This fixes a failing test case.
This commit defines the ‘Any’ keyword, implements parsing for composing
types with an infix ‘&’, and provides a fixit to convert ‘protocol<>’
- Updated tests & stdlib for new composition syntax
- Provide errors when compositions used in inheritance.
Any is treated as a contextual keyword. The name ‘Any’
is used emit the empty composition type. We have to
stop user declaring top level types spelled ‘Any’ too.
Before, a keyword in an inheritance clause would lead to a long list of errors
not really showing what was wrong.
A special case is added to handle protocol composition; in inheritance clauses
the protocols don't have to be composed with 'protocol<>'.
Having bound types in TypeReprs causes trouble in several places
(mostly involving type-checking of generics), and doesn't really fit
with TypeReprs being a mostly syntactic construct. Eliminate some code
paths using getBoundType(), and make the others do the same thing for
getBoundDecl() and getBoundType(). As part of the latter, provide
TypeBase::getDirectlyReferencedTypeDecl() to more easily map from type
to the named declaration.
Swift SVN r32018
(Note that this registry isn't fully enabled yet; it's built so that
we can test it, but has not yet taken over the primary task of
managing conformances from the existing system).
The conformance registry tracks all of the protocols to which a
particular nominal type conforms, including those for which
conformance was explicitly specified, implied by other explicit
conformances, inherited from a superclass, or synthesized by the
implementation.
The conformance registry is a lazily-built data structure designed for
multi-file support (which has been a problematic area for protocol
conformances). It allows one to query for the conformances of a type
to a particular protocol, enumerate all protocols to which a type
conforms, and enumerate all of the conformances that are associated
with a particular declaration context (important to eliminate
duplicated witness tables).
The conformance registry diagnoses conflicts and ambiguities among
different conformances of the same type to the same protocol. There
are three common cases where we'll see a diagnostic:
1) Redundant explicit conformance of a type to a protocol:
protocol P { }
struct X : P { }
extension X : P { } // error: redundant explicit conformance
2) Explicit conformance to a protocol that collides with an inherited
conformance:
protocol P { }
class Super : P { }
class Sub : Super, P { } // error: redundant explicit conformance
3) Ambiguous placement of an implied conformance:
protocol P1 { }
protocol P2 : P1 { }
protocol P3 : P1 { }
struct Y { }
extension Y : P2 { }
extension Y : P3 { } // error: ambiguous implied conformance to 'P1'
This happens when two different explicit conformances (here, P2 and
P3) placed on different declarations (e.g., two extensions, or the
original definition and other extension) both imply the same
conformance (P1), and neither of the explicit conformances imply
each other. We require the user to explicitly specify the ambiguous
conformance to break the ambiguity and associate the witness table
with a specific context.
Swift SVN r26067
Instead, just check the generic parameters, then do a lookup as usual in the
enclosing context.
Fixes crash suite #58 and quite a few others (~200). This looks way more
impressive than it is; in most of these test cases it's the exact same
pattern causing the crash, and that pattern was just the last outstanding
crash trigger in a sea of garbage. (The few deleted tests were identical
to #58.)
Swift SVN r24748
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
