We were not handling IUO results of @optional protocol methods
properly, sometimes forcing the @optional requirement rather than the
result of the call.
Fixes rdar://problem/37240984.
Before matching witnesses, ensure that we have a valid signature, and be
more tolerant of null generic environments by using the
mapTypeIntoContext entry point meant to handle null.
We haven't managed to get a decent reproducer for this, but it's
happening often enough, and this change hardens the affected code
paths.
Should fix rdar://problem/37255982.
When we form an overload set containing two generic functions, where
one is more specialized than the other, "favor" the more-specialized
function in the constraint system so we won't explore any paths
involving the less-specialized function when the more-specialized
version applies. This should be a strict improvement, because
previously we would have always gone down both paths.
Fixes rdar://problem/37371815, taking this exponential example linear.
Also remove the decl from the known decls and remove a
bunch of code referencing that decl as well as a bunch of other
random things including deserialization support.
This includes removing some specialized diagnostics code that
matched the identifier ImplicitlyUnwrappedOptional, and tweaking
diagnostics for various modes and various issues.
Fixes most of rdar://problem/37121121, among other things.
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.
If something that we are trying to contextually bind is a nested type inside
protocol or protocol extension, let's try to find the innermost conforming type
from the current declaration context and map Self parameter of the protocol
to that nominal type. Since nested types in protocols aren't yet implemented this
is going to result in failure, but that's better than crashing.
Resolves: rdar://problem/36449760
When binding an optional value, or function that returns an optional
value, if that value was produced from a decl that was declared an
IUO, create a disjunction.
After solving, make use of the disjunction choices in rewriting
expressions to force optionals where needed.
This is disabled for now, as it results in a source compatibility
issue without associated changes that actually start generating
Optional<T> in place of ImplicitlyUnwrappedOptional<T>. It's
complicated, but basically having two '??' (one returning T, one
returning T?) and creating a disjunction where the first (favored)
choice is ImplicitlyUnwrappedOptional<T> and second is T results in
our selecting the wrong '??' in some cases.
Use this in places where we have a decl that is marked with the
ImplicitlyUnwrappedOptionalAttr so that we can distinguish in the
solver which decls need to be potentially unwrapped in order to type
check successfully.
Add a new OverloadChoiceKind for decls that are either IUO-typed, or
function-typed meaning that the function result type is IUO-typed.
Not currently used, so NFC.
Instead of binding collection types directly let's try to
bind using temporary type variables substituted for element
types, that's going to ensure that subtype relationship is
always preserved.
Resolves: rdar://problem/35541153
When opening generic types with type parameter requirements,
add information about requirement location to the locator of each
generated constraint to make it easier to extract such information
if needed.
We can't construct a nominal type with an ErrorType as a
parent, so in the bad circular case, return a Type() instead
to bail out of transform() altogether.
While trying to find a fixed type for a given type variable, check if
it has representative and if it does, reflect that in the returned type.
Resolves: rdar://problem/34670592
The base mutability of storage is part of the signature, so be sure
to compute that during validation. Also, serialize it as part of
the storage declaration, and fix some places that synthesize
declarations to set it correctly.
When applying a solution containing an unbound reference to
an instance method of a class, the type of the new expression
did not match the type in the constraint system.
Usually this was papered over because CSApply is sprinkled
with coerceToType() calls, but we would crash when passing
an unbound reference to a generic function, or type(of:).
A generic signature like <T : SomeClass> would create
a subtype constraint between the type variable for T and
SomeClass. This is too loose, because a subclass existential
like 'SomeClass & SomeProto' is a subtype of SomeClass, but
cannot bind to T, because it is not representationally a
single retainable pointer.
Fixes <rdar://problem/32617814>, <https://bugs.swift.org/browse/SR-5142>.
Also, begin to pass around base types instead of raw InOutType types. Ideally, only Sema needs to deal with them, but this means that a bunch of callers need to unwrap any inouts that might still be lying around before forming these types.
Multiple parts of the compiler were slicing, dicing, or just dropping these flags. Because I intend to use them for the new function type representation, I need them to be preserved all across the compiler. As a first pass, this stubs in what will eventually be structural rules as asserts and tracks down all callers of consequence to conform to the new invariants.
This is temporary.
Special DeclNames represent names that do not have an identifier in the
surface language. This implies serializing the information about whether
a name is special together with its identifier (if it is not special)
in both the module file and the swift lookup table.
By default, end expression type checking after the elapsed process time
is more than 60 seconds for the current expression. This threshold can
be overridden by using -solver-expression-time-threshold=<seconds>.
Resolves rdar://problem/32859654
Track outcomes of `conformsToProtocol` calls in `simplifyConformanceConstraints`
to be able to validate conformances when solution is formed to avoid returning
solutions with nominal types with invalid conformances to protocols.
- Unqualified lookup was incorrectly checking generic arguments even
when resolving interface types, resulting in a bogus 'Self does
not conform to P' error when referencing a generic typealias from
inside a protocol.
- The generic argument check was also done incorrectly if the
underlying type did not contain any type parameters, resulting
in bogus ErrorTypes. Just remove the no-type-parameter
"optimization" instead, since it was working around another
crash.
- When opening up a generic typealias in the constraint solver, we
did the wrong thing if the generic typealias was defined in a
protocol, producing concrete substitutions for the parent type
instead of a 'Self := ParentType' substitution.
Fixes <rdar://problem/32633645>.
