Stop creating ImplicitlyUnwrappedOptional<T> so that we can remove it
from the type system.
Enable the code that generates disjunctions for Optional<T> and
rewrites expressions based on the original declared type being 'T!'.
Most of the changes supporting this were previously merged to master,
but some things were difficult to merge to master without actually
removing IUOs from the type system:
- Dynamic member lookup and dynamic subscripting
- Changes to ensure the bridging peephole still works
Past commits have attempted to retain as much fidelity with how we
were printing things as possible. There are some cases where we still
are not printing things the same way:
- In diagnostics we will print '?' rather than '!'
- Some SourceKit and Code Completion output where we print a Type
rather than Decl.
Things like module printing via swift-ide-test attempt to print '!'
any place that we now have Optional types that were declared as IUOs.
There are some diagnostics regressions related to the fact that we can
no longer "look through" IUOs. For the same reason some output and
functionality changes in Code Completion. I have an idea of how we can
restore these, and have opened a bug to investigate doing so.
There are some small source compatibility breaks that result from
this change:
- Results of dynamic lookup that are themselves declared IUO can in
rare circumstances be inferred differently. This shows up in
test/ClangImporter/objc_parse.swift, where we have
var optStr = obj.nsstringProperty
Rather than inferring optStr to be 'String!?', we now infer this to
be 'String??', which is in line with the expectations of SE-0054.
The fact that we were only inferring the outermost IUO to be an
Optional in Swift 4 was a result of the incomplete implementation of
SE-0054 as opposed to a particular design. This should rarely cause
problems since in the common-case of actually using the property rather
than just assigning it to a value with inferred type, we will behave
the same way.
- Overloading functions with inout parameters strictly by a difference
in optionality (i.e. Optional<T> vs. ImplicitlyUnwrappedOptional<T>)
will result in an error rather than the diagnostic that was added
in Swift 4.1.
- Any place where '!' was being used where it wasn't supposed to be
allowed by SE-0054 will now treat the '!' as if it were '?'.
Swift 4.1 generates warnings for these saying that putting '!'
in that location is deprecated. These locations include for example
typealiases or any place where '!' is nested in another type like
`Int!?` or `[Int!]`.
This commit effectively means ImplicitlyUnwrappedOptional<T> is no
longer part of the type system, although I haven't actually removed
all of the code dealing with it yet.
ImplicitlyUnwrappedOptional<T> is is dead, long live implicitly
unwrapped Optional<T>!
Resolves rdar://problem/33272674.
SE-0072 took implicit bridging conversions away, which regressed the ability to express NSDictionaries as dictionary literals and index them using literal keys. Address this by changing the signature of init(dictionaryLiteral:) to use Hashable and Any, and by replacing the subscript from Objective-C with one using _Hashable that does the bridging on the user's behalf. This largely restores the QoI of working with NS collections.
One last bit of SE-0072. We shouldn't fall back to bridged classes in the absence of type context for literals anymore. By itself, this kind of hoses the use of literals with NS types, but I think we can get most of the QoI back with overlay changes I plan to propose following this.
This is a squash of the following commits:
* [SE-0054] Import function pointer arg, return types, typedefs as optional
IUOs are only allowed on function decl arguments and return types, so
don't import typedefs or function pointer args or return types as IUO.
* [SE-0054] Only allow IUOs in function arg and result type.
When validating a TypeRepr, raise a diagnostic if an IUO is found
anywhere other thn the top level or as a function parameter or return
tpye.
* [SE-0054] Disable inference of IUOs by default
When considering a constraint of the form '$T1 is convertible to T!',
generate potential bindings 'T' and 'T?' for $T1, but not 'T!'. This
prevents variables without explicit type information from ending up with
IUO type. It also prevents implicit instantiation of functions and types
with IUO type arguments.
* [SE-0054] Remove the -disable-infer-iuos flag.
* Add nonnull annotations to ObjectiveCTests.h in benchmark suite.
Fixes rdar://problem/14776565 (AnyObject lookup for Objective-C
properties with custom getters) and rdar://problem/17184411 (allowing
__attribute__((swift_name("foo"))) to work on anything).
This requires a bit of special handling because we override the getter's type
in the importer, to make sure it's compatible with the setter, but other than
that we just use the information from the apinotes file.
<rdar://problem/17891179>
Swift SVN r21027
This allows "obj.description!" to work on iOS when 'obj' is an AnyObject,
even though 'description' is an implicit property created by the importer.
Swift SVN r18149
The old ones were:
- print/println
- printAny
- printf
- Console
The new printing story is just print/println. Every object can be printed.
You can customize the way it is printed by adopting Printable protocol. Full
details in comments inside stdlib/core/OutputStream.swift.
Printing is not completely finished yet. We still have ReplPrintable, which
should be removed, string interpolation still uses String constructors, and
printing objects that don't conform to Printable will result in printing
mangled names.
Swift SVN r18001
The name used for name lookup of subscript operators is "__subscript",
but when looking into an Objective-C module we instead need to look
for methods with the subscripting selectors, e.g.,
objectAtIndexedSubscript:/objectForKeyedSubscript:. Do so, and make
sure that deserializing the method first still creates the subscript
declaration.
Fixes the majority of <rdar://problem/14656624>. We can subscript 'id' now.
Swift SVN r8700
