Within the where clause of a constrained (protocol) extension, allow
us to find associated types of that protocol and anything it inherits
via unqualified lookup, e.g.,
extension SequenceType where Generator.Element : Equatable { }
rather than
extension SequenceType where Self.Generator.Element : Equatable { }
Implements rdar://problem/20722467.
Swift SVN r28208
AnyObject won't always be a protocol, and it may be de-protocol'ified
well before we get the ability to extend an arbitrary type (if that
ever happens), so ban this for now.
Swift SVN r28120
We might be looking at a protocol requirement, which conforms to a
protocol but has a null conformance. Also, don't bother looking at
completeness: it doesn't matter. Fixes rdar://problem/20608438.
Swift SVN r27860
The rule changes are as follows:
* All functions (introduced with the 'func' keyword) have argument
labels for arguments beyond the first, by default. Methods are no
longer special in this regard.
* The presence of a default argument no longer implies an argument
label.
The actual changes to the parser and printer are fairly simple; the
rest of the noise is updating the standard library, overlays, tests,
etc.
With the standard library, this change is intended to be API neutral:
I've added/removed #'s and _'s as appropriate to keep the user
interface the same. If we want to separately consider using argument
labels for more free functions now that the defaults in the language
have shifted, we can tackle that separately.
Fixes rdar://problem/17218256.
Swift SVN r27704
Inference of type witnesses for associated types was previously
implemented as part of value witness matching in the constraint
solver. This led to a number of serious problems, including:
- Recursion problems with the solver hunting for a type witness,
which triggers more attemts to match value witnesses...
- Arbitrarily crummy attempts to break the recursion causing
type-check failures in fun places.
- Ordering dependencies abound: different results depending on which
value witnesses were satisfied first, failures because of the order
in which we attempted to infer type witnesses, etc.
This new implementation of type witness inference uses a separate pass
that occurs whenever we're looking for any type witness, and solves
all of the type witnesses within a given conformance
simultaneously. We still look at potential value witnesses to infer
type witnesses, but we match them structurally, without invoking the
constraint solver.
There are a few caveats to this implementation:
* We're not currently able to infer type witnesses from value
witnesses that are global operators, so some tricks involving global
operators (*cough* ~> *cough*) might require some manually-specified
type witnesses. Note that the standard library doesn't include any
such cases.
* Yes, it's another kind of solver. At simple one, fortunately.
On the other hand, this implementation should be a big step forward:
* It's far more predictable, order-invariant, and non-recursive.
* The diagnostics for failures to infer type witnesses have
improved.
Fixes rdar://problem/20598513.
Swift SVN r27616
Handle substitutions properly when a typealias declared in a protocol
extension is used to satisfy an associated type requirement. Fixes
rdar://problem/20564605.
Swift SVN r27490
For structs/enums, this was already the case. For classes, we simply
need to ensure that we always look at the extensions of protocols to
which the class conforms.
Swift SVN r26773
Compare the generic signatures so that we get appropriate partial
ordering among constrained extensions, extensions of inherited
protocols, etc. Finishes rdar://problem/20335936.
Swift SVN r26726
Implement simplistic partial ordering rules for members of protocol
extensions. Specifically:
- A member of a concrete type is more specialized than a member of a
protocol extension
- A member of a protocol extension of P1 is more specialized than a
member of a protocol extension of P2 if P1 inherits from P2
This achieves most of what rdar://problem/20335936 covers, but does
not yet handle ordering between constrained protocol extensions.
Swift SVN r26723
Start parsing a "trailing" where clause for extension declarations, which follows the extended type name and (optional) inheritance clause. Such a where clause is only currently permitted for protocol extensions right now.
When used on a protocol extension, it allows one to create a more-constrained protocol extension, e.g.,
extension CollectionType where Self.Generator.Element : Equatable { ... }
which appears to be working, at least in the obvious cases I've tried.
More cleanup, tests, and penance for the previous commit's "--crash" introductions still to come.
Swift SVN r26689
Remove the semantic restrictions that prohibited extensions of
protocol types, and start making some systematic changes so that
protocol extensions start to make sense:
- Replace a lot of occurrences of isa<ProtocolDecl> and
dyn_cast<ProtocolDecl> on DeclContexts to use the new
DeclContext::isProtocolOrProtocolExtensionContext(), where we want
that behavior to apply equally to protocols and protocol extensions.
- Eliminate ProtocolDecl::getSelf() in favor of
DeclContext::getProtocolSelf(), which produces the appropriate
generic type parameter for the 'Self' of a protocol or protocol
extension. Update all of the callers of ProtocolDecl::getSelf()
appropriately.
- Update extension validation to appropriately form generic
parameter lists for protocol extensions.
- Methods in protocol extensions always use the witnesscc calling
convention.
At this point, we can type check and SILGen very basic definitions of
protocol extensions (without associated types, IRGen crashes, etc.)
with methods that can call protocol requirements, generic free
functions, and other methods within the same protocol extension.
This is identical to r26579; the prior commit addressed the underlying
conformance substitution problem that caused rdar://problem/20320393
and subsequent reversion of r26579.
Swift SVN r26639
We do a silly little dance here of finding all of the members of
protocols and their extensions, then deleting the protocol members. In
the future, this is the place where we should handle the protocol
requirement -> witness mapping, including handling derived
conformances.
Basic protocol extensions seem to be working now:
extension SequenceType {
var myCount: Int {
var result = 0
for x in self {
++result
}
return result
}
}
println(["a", "b", "c", "d"].myCount) // 4, duh
Swift SVN r26617
Remove the semantic restrictions that prohibited extensions of
protocol types, and start making some systematic changes so that
protocol extensions start to make sense:
- Replace a lot of occurrences of isa<ProtocolDecl> and
dyn_cast<ProtocolDecl> on DeclContexts to use the new
DeclContext::isProtocolOrProtocolExtensionContext(), where we want
that behavior to apply equally to protocols and protocol extensions.
- Eliminate ProtocolDecl::getSelf() in favor of
DeclContext::getProtocolSelf(), which produces the appropriate
generic type parameter for the 'Self' of a protocol or protocol
extension. Update all of the callers of ProtocolDecl::getSelf()
appropriately.
- Update extension validation to appropriately form generic
parameter lists for protocol extensions.
- Methods in protocol extensions always use the witnesscc calling
convention.
At this point, we can type check and SILGen very basic definitions of
protocol extensions with methods that can call protocol requirements,
generic free functions, and other methods within the same protocol
extension.
Regresses four compiler crashers but improves three compiler
crashers... we'll call that "progress"; the four regressions all hit
the same assertion in the constraint system that will likely be
addressed as protocol extensions starts working.
Swift SVN r26579
