Detect and fix situations when (force) unwrap is used on
a non-optional type, this helps to diagnose invalid unwraps
precisely and provide fix-its.
Resolves: [SR-8977](https://bugs.swift.org/browse/SR-8977)
Resolves: rdar://problem/45218255
When we determine that an optional value needs to be unwrapped to make
an expression type check, use notes to provide several different
Fix-It options (with descriptions) rather than always pushing users
toward '!'. Specifically, the errors + Fix-Its now looks like this:
error: value of optional type 'X?' must be unwrapped to a value of
type 'X'
f(x)
^
note: coalesce using '??' to provide a default when the optional
value contains 'nil'
f(x)
^
?? <#default value#>
note: force-unwrap using '!' to abort execution if the optional
value contains 'nil'
f(x)
^
!
Fixes rdar://problem/42081852.
That is, if there's a problem with a witness, and the witness comes
from a different extension from the conformance (or the original type,
when the conformance is on an extension), put the main diagnostic on
the conformance, with a note on the witness. This involves some
shuffling and rephrasing of existing diagnostics too.
There's a few reasons for this change:
- More context. It may not be obvious why a declaration in file
A.swift needs to be marked 'public' if you can't see the conformance
in B.swift.
- Better locations for imported declarations. If you're checking a
conformance in a source file but the witness came from an imported
module, it's better to put the diagnostic on the part you have
control over. (This is especially true in Xcode, which can't display
diagnostics on imported declarations in the source editor.)
- Plays better with batch mode. Without this change, you can have
diagnostics being reported in file A.swift that are tied to a
conformance declared in file B.swift. Of course the contents of
A.swift also affect the diagnostic, but compiling A.swift on its
own wouldn't produce the diagnostic, and so putting it there is
problematic.
The change does in some cases make for a worse user experience,
though; if you just want to apply the changes and move on, the main
diagnostic isn't in the "right place". It's the note that has the info
and possible fix-it. It's also a slightly more complicated
implementation.
And provide better semantic background by surrounding 'nil' in ticks when it is referred to as a value
Added missing tests for certain cases involving nil capitalization
Introduce a new Type node, BoundNameAliasType, which describes a
reference to a typealias that requires substitutions to produce the
underlying type. This new type node is used both for references to
generic typealiases and for references to (non-generic) typealiases
that occur within generic contexts, e.g., Array<Int>.Element.
At present, the new type node is mainly useful in preserving type
sugar for diagnostics purposes, as well as being reflected in other
tools (indexing, code completion, etc.). The intent is to completely
replace NameAliasType in the future.
This restriction came from wanting to make resilient and non-resilient
code follow the same rules whenever possible, but after thinking about
it a bit more we realized there was no reason why you /wouldn't/ just
mark your structs @_fixed_layout in non-resilient libraries anyway.
Since that (currently?) doesn't affect what you can do with the struct
across module boundaries, and since the layout of the struct is
available anyway in a non-resilient library, there's no real downside,
which means it's a meaningless restriction.
The same logic doesn't /quite/ apply to classes, since classes are
normally much more flexible than structs. (For example, you could add
a stored property to a class without recompiling clients, as long as
no initializers are inlined.) But it's close enough that we don't want
to put in the restriction at this time.
All of this is about attributes that haven't been finalized yet anyway
(hence the leading underscore), but it's still useful information.
rdar://problem/37408668
This is technically a source break, but the @_fixed_layout attribute
is not official yet. If anyone really cares, we can make this
conditional on -swift-version 5 later, but I'd rather not.
This change is necessary so that we can give property initializers
non-public linkage. Currently they are public, because they can be
referenced from inlinable initializers.
Now that property initializers inside a @_fixed_layout type can
only reference public symbols, they no longer have to be public,
but making that change requires a bit more work.
Now that struct initializers "just" fall into the delegating case when
they're made inlinable, the only interesting case is class
initializers, which can be checked in a more direct way than what we
were doing before.
(and when the struct in question is non-fixed-layout, which was
already implemented)
This ensures that these initializers are never fieldwise in Swift 5
mode, which makes it safe for library authors to add new fields.
Initializers for non-fixed-layout structs that are inlinable or
are defined in a different module are treated as delegating
initializers.
Previously, only initializers containing a 'self.init' call were
delegating; initializers that assigned to 'self' were not, which
resulted in DI treating them as a root initializer where the
stored 'self' value was exploded into a series of stores to each
stored property member.
They were not resilient as a result.
Fixes <https://bugs.swift.org/browse/SR-5649>,
<rdar://problem/33767516>.
This allows a library to "fix" an initializer that should have been
failable or non-failable by gating the change on the user's version of
Swift. Failability (and whether or not the initializer throws) is
something that doesn't change the "overload signature", so normally
the compiler would call this an invalid redeclaration. But since only
one version can be active at a time based on the client context, there
won't be a problem in practice.
https://bugs.swift.org/browse/SR-4171 / rdar://problem/30470854
I realized in the process of doing this that methods may also have
mismatched 'throws', and we should allow that as well. Next commit.
If a convenience initializer in a subclass delegated to an inherited initializer from its base, we would end up type-checking the reference to the base class constructor as returning the base type, leading to type mismatches in the result AST and downstream crashes. We can wrap up the synthesized OtherConstructorRefExpr in a CovariantFunctionConversionExpr, which will trick the type checker into propagating the covariant result that gets rebound to `self` on return, avoiding this problem. (For now, I'm avoiding making the constructor decl formally have a Self return type, since that exposes a bunch of downstream breakage in code paths that only expect FuncDecls to be covariant, and also affects the mangling of constructors, causing a bunch of test case thrash we really don't want to inflict on the 3.1 branch.)
Value type initializers must initialize stored properties directly
if they do not delegate to another initializer via self.init().
Since direct stored property access is not permitted for resilient
value types from outside their resilience domain, this means that
such initializers are prohibited in two cases:
- If the initializer is defined in an extension from outside the
value type's resilience domain
- If the initializer is public and @_inlineable, since it might get
inlined outside the value type's resilience domain
Right now, such initializers cannot *assign* to self either;
I filed <https://bugs.swift.org/browse/SR-3686> to track the issue.
Swift does not currently support user-defined factory inits. With
import as member, we're seeing many C functions now imported as
initializers, which gives users the false hope that they can define
their own factory inits as conveinence inits in extensions of CF
types. We issue an explicit error now, rather than crashing later.
With the previous resolveTypeInContext() patch, a few compiler
crashers regressed with this problem, presumably because we were now
performing lookups in more contexts than before.
This is a class of problems where we would attempt a recursive
validation:
1) Generic signature validation begins for type T
2) Name lookup in type context finds a non-type declaration D nested in T
3) Generic signature validation begins for D
4) The outer generic context of D is T, but T doesn't have a generic
signature yet
The right way to break such cycles is to implement the iterative
decl checker design. However when the recursion is via name lookup,
we can try to avoid the problem in the first place by not validating
non-type declarations if the client requested a type-only lookup.
Note that there is a small semantic change here, where programs that
were previously rejected as invalid because of name clashes are
now valid. It is arguable if we want to allow stuff like this or not:
class A {
func A(a: A) {}
}
or
class Case {}
enum Foo {
case Case(Case)
}
However at the very least, the new behavior is better because it
gives us an opportunity to add a diagnostic in the right place
later. The old diagnostics were not very good, for example the
second example just yields "use of undeclared type 'Case'".
In other examples, the undeclared type diagnostic would come up
multiple times, or we would generate a cryptic "type 'A' used within
its own definition".
As far as I understand, this should not change behavior of any existing
valid code.
<stdin>:1:16: error: nil cannot initialize specified type 'Int'
var foo: Int = nil
^
<stdin>:1:10: note: add '?' to form the optional type 'Int?'
var foo: Int = nil
^
?
Migrate the check for whether a given type is representable in
Objective-C, which is currently used to verify when @objc can be
inferred or verify that an explicitly-written @objc is well-formed,
from Sema into a set of queries on the Type within the AST library, so
it can be used in other parts of the compiler.
As part of this refactoring, clean up and improve a number of aspects
of this code:
* Unify the "trivially representable" and "representable" code paths
into a single code path that covers these cases. Clarify the
different levels of "representable" we have in both the code and
in comments.
* Distinguish between representation in C vs. representation in
Objective-C. While we aren't using this now, I'm anticipating it
being useful to allow exporting C interfaces via @_cdecl (or
similar).
* Eliminate the special cases for bridging String/Array/Dictionary/Set
with their Foundation counterparts; we now consult
_ObjectiveCBridgeable conformances exclusively to get this
information.
* Cache foreign-representation information on the ASTContext in a
manner that will let us more easily get the right answer across
different contexts while providing more sharing than the TypeChecker
version.
Annoyingly, this only seemed to fix a small class of error where we
were permitting Unsafe(Mutable)Pointer<T> to be representable in
Objective-C when T was representable but not trivially representable,
e.g., T=String or T=AnyObject.Type.
Designated initializers in NSManagedObject subclasses, or other
classes with @requires_stored_property_inits cannot assign to
stored properties before doing a super.init() delegation.
Assignments after are OK.
DI did the wrong thing by creating a bitmap with only one bit,
but proceeding down the usual designated initializer path.
Now, handle [derivedselfonly] more like a convenience initializer,
with no stored property access allowed prior to delegation.
Also clean up duplicated diagnostics between designated and
convenience initializers, and make convenience initializers
diagnose method calls or property accesses on self in the same
manner as designated initializers.
Fixes <rdar://problem/22110837>.
Swift SVN r32858
Put in some rudimentary logic for finding circular references within
the iterative type checker and diagnosing those cycles. The
"rudimentary" part is because we're performing linear searches within
a stack rather than keeping a proper dependency graph, which is
inefficient and could display longer cycles than are actually
present. Additionally, the diagnostic is not specialized to the actual
query, so we get a generic "circular reference" diagnostic. OTOH, we
show all of the declarations involved in the cycle, which at least
lets the user figure out where the cycle occurred.
Enable the iterative type checker for resolving the type of a global
typealiases.
Swift SVN r32572
of providing contextual diagnostics (e.g. producing the warning in
Constraints/dynamic_lookup.swift). This drops a specific diagnostic about
force casting the result of as! which was added in the Swift 1.2 timeframe
to explain the change in cast semantics. Now that as! has been around for
a long time, it is more confusing than helpful.
Swift SVN r31887
- Enhance the branch new argument label overload diagnostic to just
print the argument labels that are the problem, instead of printing
the types inferred at the argument context. This can lead to confusion
particularly when an argument label is missing. For example before:
error: argument labels '(Int)' do not match any available overloads
note: overloads for 'TestOverloadSets.init' exist with these partially matching parameter lists: (a: Z0), (value: Int), (value: Double)
after:
error: argument labels '(_:)' do not match any available overloads
note: overloads for 'TestOverloadSets.init' exist with these partially matching parameter lists: (a: Z0), (value: Int), (value: Double)
Second, fix <rdar://problem/22451001> QoI: incorrect diagnostic when argument to print has the wrong type
by specifically diagnosing the problem when you pass in an argument to a nullary function. Before:
error: cannot convert value of type 'Int' to expected argument type '()'
after:
error: argument passed to call that takes no arguments
print(r22451001(5))
^
Swift SVN r31795
forced conversion to "_ -> T" if it will refine the type otherwise found by
doing a non-contextual type check. This allows us to diagnose calls to
non-function values with more specificity, e.g. adding another case were we
recommend "do" when using bare braces.
Swift SVN r31726
use that contextual type to guide typechecking of the callee. This allows us to
propagate that type through generic constraints effectively, making us produce
much more useful diagnostics within closures taking methods like "map" (for
example).
This fixes:
<rdar://problem/20491794> QoI closures: Error message does not tell me what the problem is
Specifically, running the testcase:
enum Color { case Unknown(description: String) }
let xs: (Int, Color) = [1,2].map({ ($0, .Unknown("")) })
produces: error: cannot convert call result type '[_]' to expected type '(Int, Color)'
Changing that to:
let xs: [(Int, Color)] = [1,2].map({ ($0, .Unknown("")) })
produces: error: missing argument label 'description:' in call
... with a fixit to introduce the label.
This also fixes most of 22333090, but we're only using this machinery for CallExprs
so far, not for operators yet.
Swift SVN r31484
