The Swift class model does not support overriding declarations where either
the overridden declaration or the overriding declaration are in an extension.
However, the Objective-C class model does, so marking the declaration as
@objc (when possible) will work around the limitation.
Customize the "cannot override declaration in extension" diagnostic to
suggest adding @objc to the overridden declaration in cases where
@objc is permitted. Fixes SR-6512 / rdar://problem/35787914.
For Swift 3 / 4:
Deprecate the spelling "ImplicitlyUnwrappedOptional", emitting a warning
and suggesting "!" in places where they are allowed according to
SE-0054.
In places where SE-0054 disallowed IUOs but we continued to accept them
in previous compilers, emit a warning suggesting "Optional" or "?" as
an alternative depending on context and treat the IUO as an Optional,
noting this in the diagnostic.
For Swift 5:
Treat "ImplicitlyUnwrappedOptional" as an error, suggesting
"!" in places where they are allowed by SE-0054.
In places where SE-0054 disallowed IUOs, emit an error suggestion
"Optional" or "?" as an alternative depending on context.
Per SE-0054, implicitly unwrapped optional is not a distinct type in the
type system, but rather just the notion that certain Optionals (denoted
by the sigil "!" rather than "?") can be implicitly unwrapped.
This is a first step in the direction of implementing this notion by
emitting a warning if the type is spelled out.
We allowed them for generic parameter inheritance clauses but
not anywhere else. While arguably this has stylistic benefits,
the restriction was not enforced consistently and was mostly a
result of implementation limitations.
Lift the restriction and fix things up where needed to make them
work. This brings us closer to allowing protocols to constrain
the 'Self' type to a subclass of a class by listing the class in
the protocol's inheritance clause, which was a feature from SE-0156,
but this doesn't quite work.
Fixes <https://bugs.swift.org/browse/SR-4678> and
<rdar://problem/31785092>.
We were checking the accessibility of the setter incorrectly.
As a result, a 'public internal(set)' property could not override
another 'public internal(set)' property; the setter had to be
public in the override, which is unnecessarily visible.
Fixes <rdar://problem/34085586>.
In today's Swift, only non-optional function parameters can be
non-escaping (and are by default). An optional function parameter uses
a function type as a generic argument to Optional, and like any other
generics that's considered an opaque and therefore possibly escaping
use of the type. This is certainly unfortunate since it means a
function parameter cannot be both Optional and non-escaping.
However, this "unfortunate" becomes a concrete problem when dealing
with Objective-C, which /does/ allow applying its 'noescape' attribute
to a callback block marked 'nullable'. This is fine for /uses/ of
methods with such parameters, but prevents anyone from /overriding/
these methods.
This patch pokes a very narrow hole into the override checking to
accomodate this: if a declaration comes from Objective-C, and it has
an optional, non-escaping closure parameter, it's okay to override it
in Swift with an optional, escaping closure parameter. This isn't
strictly safe because a caller could be relying on the
non-escaping-ness, but we don't have anything better for now. (This
behavior will probably be deprecated in the future.)
(Some people have noted that the old 'noescape' type attribute in
Swift still works, albeit with a warning. That's not something people
should have to type, though---we want to remove it from the language,
as described in SE-0103.)
rdar://problem/32903155
Using the attribute in this position is a relic from the Swift 2
days, and fixing it required letting invalid code fall through to
Sema instead of being diagnosed in Parse proper. Treat 'var'
in this position like 'let' by simply offering to remove it
instead of extracting it into a separate variable.
The general self-derived check doesn't really make sense for
conformance constraints, because we want to distinguish among
different protocol conformances.
The list of directly inherited protocols of a ProtocolDecl is already
encoded in the requirement signature, as conformance constraints where
the subject is Self. Gather the list from there rather than separately
computing/storing the list of "inherited protocols".
Previously, validateDecl() would check if the declaration had an
interface type and use that as an indication not to proceed.
However for functions we can only set an interface type after
checking the generic signature, so a recursive call to validateDecl()
on a function would "steal" the outer call and complete validation.
For generic types, this meant we could have a declaration with a
valid interface type but no generic signature.
Both cases were problematic, so narrow workarounds were put in
place with additional new flags. This made the code harder to
reason about.
This patch consolidates the flags and establishes new invariants:
- If validateDecl() returns and the declaration has no interface
type and the isBeingValidated() flag is not set, it means one
of the parent contexts is being validated by an outer recursive
call.
- If validateDecl() returns and the declaration has the
isBeingValidated() flag set, it may or may not have an interface
type. In this case, the declaration itself is being validated
by an outer recursive call.
- If validateDecl() returns and the declaration has an interface
type and the isBeingValidated() flag is not set, it means the
declaration and all of its parent contexts are fully validated
and ready for use.
In general, we still want name lookup to find things that have an
interface type but are not in a valid generic context, so for this
reason nominal types and associated types get an interface type as
early as possible.
Most other code only wants to see fully formed decls, so a new
hasValidSignature() method returns true iff the interface type is
set and the isBeingValidated() flag is not set.
For example, while resolving a type, we can resolve an unqualified
reference to a nominal type without a valid signature. However, when
applying generic parameters, the hasValidSignature() flag is used
to ensure we error out instead of crashing if the generic signature
has not yet been formed.
This leads to some bad recursion through validateDecl(), even
when called from the ITC. We already had machinery to add
implicit constructors later, it just had to be extended to
do it for the superclass as well.
One minor revision: this lifts the proposed restriction against
overriding a non-open method with an open one. On reflection,
that was inconsistent with the existing rule permitting non-public
methods to be overridden with public ones. The restriction on
subclassing a non-open class with an open class remains, and is
in fact consistent with the existing access rule.
This at least emits notes when someone overrides something but
gets the types a little wrong (more than just mismatched optionals,
as handled in d669d152).
Part of rdar://problem/26183575
In many places, we're interested in whether a type with archetypes *might be* a superclass of another type with the right bindings, particularly in the optimizer. Provide a separate Type::isBindableToSuperclassOf method that performs this check. Use it in the devirtualizer to fix rdar://problem/24993618. Using it might unblock other places where the optimizer is conservative, but we can fix those separately.
Now that we have lazy metadata accessors for classes and vtable thunking, we don't have any reason to prevent concrete subclasses of generic base classes. Wire up IRGen to lazily instantiate the superclass for concrete derived classes when their metadata is accessed, using a runtime function that installs all the necessary pointers and metadata and registers the fully-initialized class with the ObjC runtime.
Swift SVN r28520
<rdar://problem/15975935> warning that you can use 'let' not 'var'
<rdar://problem/18876585> Compiler should warn me if I set a parameter as 'var' but never modify it
<rdar://problem/17224539> QoI: warn about unused variables
This uses a simple pass in MiscDiagnostics that walks the body of an
AbstractFunctionDecl. This means that it doesn't warn about unused properties (etc),
but it captures a vast majority of the cases.
It also does not warn about unused parameters (as a policy decision) because it is too noisy,
there are a variety of other refinements that could be done as well, thoughts welcome.
Swift SVN r28412
var/let bindings to _ when they are never used, and use some values that
are only written. This is a testsuite cleanup, NFC. More to come.
Swift SVN r28406
The code would generate different diagnosics depending on
the cycle having length 1 or longer. The length 1 case
was broken if the path had a prefix that wasn't part
of the cycle, eg if we have C : A, A : A and visit C
first.
Swift SVN r28317
If you want to make the parameter and argument label the same in
places where you don't get the argument label for free (i.e., the
first parameter of a function or a parameter of a subscript),
double-up the identifier:
func translate(dx dx: Int, dy: Int) { }
Make this a warning with Fix-Its to ease migration. Part of
rdar://problem/17218256.
Swift SVN r27715
Replace the loop over all known protocols with a query into the
actual conformance lookup table, which more properly deals with
out-of-order conformance queries, inheritance of protocol
conformances, and conformance queries in multi-file situtations.
The SILGen test change is because we're no longer emitting redundant
conformances, while the slight diagnostic regression in
circular-inheritance cases is because we handle circular inheritance
very poorly throughout the compiler.
While not the end, this is a major step toward finishing
rdar://problem/18448811.
Swift SVN r26299
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
Previously the "as" keyword could either represent coercion or or forced
downcasting. This change separates the two notions. "as" now only means
type conversion, while the new "as!" operator is used to perform forced
downcasting. If a program uses "as" where "as!" is called for, we emit a
diagnostic and fixit.
Internally, this change removes the UnresolvedCheckedCastExpr class, in
favor of directly instantiating CoerceExpr when parsing the "as"
operator, and ForcedCheckedCastExpr when parsing the "as!" operator.
Swift SVN r24253
Also warn when the subclass returns 'T!' where the superclass returns 'T?'.
In both cases, allow silencing by wrapping the 'T!' in parentheses.
This is intended to provide migration help as Objective-C classes get
annotated for nullability. Because of that, the check is only run on @objc
classes, though it's not limited to classes that actually come from Objective-C
because of (a) deep subclass chains that may all need updating, and (b) ease
of testing.
<rdar://problem/17892184>
Swift SVN r21001
