Since `simplifyRestrictedConstraintImpl` has both parent types and
does nested type matching it's a good place to diagnose top-level
contextual problems like mismatches in underlying types of optionals.
Since opening closure body is now delayed until contextual type becomes
available it's possible to infer anonymous parameters as being variadic
based on context and propagate that information down to the closure body.
Resolves: rdar://problem/41416758
* WIP implementation
* Cleanup implementation
* Install backedge rather than storing array reference
* Add diagnostics
* Add missing parameter to ResultFinderForTypeContext constructor
* Fix tests for correct fix-it language
* Change to solution without backedge, change lookup behavior
* Improve diagnostics for weak captures and captures under different names
* Remove ghosts of implementations past
* Address review comments
* Reorder member variable initialization
* Fix typos
* Exclude value types from explicit self requirements
* Add tests
* Add implementation for AST lookup
* Add tests
* Begin addressing review comments
* Re-enable AST scope lookup
* Add fixme
* Pull fix-its into a separate function
* Remove capturedSelfContext tracking from type property initializers
* Add const specifiers to arguments
* Address review comments
* Fix string literals
* Refactor implicit self diagnostics
* Add comment
* Remove trailing whitespace
* Add tests for capture list across multiple lines
* Add additional test
* Fix typo
* Remove use of ?: to fix linux build
* Remove second use of ?:
* Rework logic for finding nested self contexts
If return type is a function, it's possible to return a closure
which can have some of its arguments unused in the body e.g.
`let _: () -> ((Int) -> Void) = { return { } }`
In this case resulting closure has to use its only parameter or
explictly ignore it by declaring `_ in`.
Initially this problem was only detected and diagnosed for calls.
So let's extend it to function conversions as well e.g.:
```swift
func foo<T>(_: [T]) {}
func bar<T>(_ f: (T...) -> ()) {}
bar { foo($0) }
```
In the past, this error was applied inconsistently, so diagnosing it
correctly is now a source-breaking change. Instead, diagnose it correctly,
but as a warning.
automatically.
This commit also renames `ConstraintSystem::recordHole/isHole` to
`recordPotentialHole` and `isPotentialHole` to make it clear that
we don't know for sure whether a type variable is a hole until it's
bound to unresolved.
This helps us to better diagnose failures related to generic
requirements like `T == [Int]` as well as protocol compositions,
which require deep equality check.
Instead, check them and their error handling right away.
In addition to fixing the crash in the radar, this also causes
us to emit unused variable warnings in functions containing
local functions.
Eventually, TC.definedFunctions should go away altogether.
Fixes <rdar://problem/53956342>.
If a syntax sugared type like Array had an unresolved type, it used to print as `[_]` in diagnostics, which could be confusing.
Instead, desugar these unresolved types before printing, so Array, for example, prints as `Array<_>`.
Currently this only applies to Array, Dictionary, and Optional.
This improves the diagnostic for trailing closures in statement conditions to catch cases where one or more trailing closures are used in a chain composed of multiple calls
Enhance call-argument matching to reject trailing closures that match up
with parameters that cannot accept closures at all.
Fixes rdar://problem/50362170.
Let's keep track of type mismatch between type deduced
for the body of the closure vs. what is requested
contextually, it makes it much easier to diagnose
problems like:
```swift
func foo(_: () -> Int) {}
foo { "hello" }
```
Because we can pin-point problematic area of the source
when the rest of the system is consistent.
Resolves: rdar://problem/40537960
We previously allowed these closures to default to (), but be inferred
as other types as well, which means that we will find some expressions
to be ambiguous because we end up finding multiple viable solutions
where there is really only one reasonable solution.
Fixes: rdar://problem/42337247
This fixes a subtle issue where, during single-expression closure type inference, we would ask for the settability of local variables from the outer function's context, leading us to mistakenly consider them mutable inside single-expression closure contexts. DI would catch some but not all violations of the expected semantics here.
Currently we always use 'FunctionResult' as a path element when matching
function result types, but closure result type is allowed to be implicitly
converted to Void, which means we need to be careful when to use
'FunctionResult' and 'ClosureResult'.
Resolves: rdar://problem/37790062
Calls involving single trailing closure arguments require special
handling because we don't have as much contextual information
about function/argument types as in with regular calls, which means
that diagnosing such situations only by `visitApplyExpr`
yields subpar results.
Resolves: SR-4836.
```swift
func foo(f: Void) -> ()) {}
```
This compiler currently suggests we change this to:
```swift
func foo(f: (Void) -> ()) {}
```
That's `(()) -> ()`, almost certainly not what someone wants in Swift
4. We should suggest changing that to:
```swift
func foo(f: () -> ()) {}
```
Additionally,
```swift
func foo(f: (Void) -> ()) {}
```
Should trigger a warning that the `(Void)` input type is `(())`, and you
can't supply `()` to it in Swift 4, and suggest a fix-it change it to:
```swift
func foo(f: () -> ()) {}
```
rdar://problem/32143617
(in Swift 4 mode)
There are a lot of other things that overload ranking does *not* take
into account, and I intend to file a more general bug about that, but
this should resolve some of the most egregious ambiguities with Swift
3's import rules (SE-0005, particularly "omit needless words" and
adding default arguments).
Finishes rdar://problem/25607552.
The "map into the right context" logic was only getting hit
if we didn't exit early to handle the lvalue case. Move it up
to the top of the function.
Fixes <https://bugs.swift.org/browse/SR-4369>.
rdar://problem/21193574 says that this warning dates back to when closure args before default args used to be considered as trailing closures. This is not the case anymore so Jordan suggested we remove the warning.
`1 { }` was parsed as a call expression with a trailing closure. This made the diagnostics for `var x = 1 { get { ... } }` extremely bad. Resolves SR-3671.
This still doesn't work in a number of cases, but fixes a case
that used to work in Swift 3.0 which was affecting the Dollar.swift
library.
Fixes <rdar://problem/29007725>.
Fixes SR-2757.
Variables in capture lists are treated as 'let' constants, which can
result in misleading, incorrect diagnostics. Mark them as such in order
to produce better diagnostics, by adding an extra parameter to the
VarDecl initializer.
Alternatively, these variables could be marked as implicit, but that
results in other diagnostic problems: capture list variables that are
never used produce warnings, but these warnings aren't normally emitted for
implicit variables. Other assertions in the compiler also misfire when
these variables are treated as implicit.
Another alternative would be to walk up the AST and determine whether
the `VarDecl`, but there doesn't appear to be a way to do so.
This reverts commit e172383e2f.
There were two problems with this commit:
- This was a source-breaking change and should have been feature-gated.
- It only addressed one narrow case of SE-0110.
Fixes <rdar://problem/28621719>.
Previously, getInterfaceType() would return getType() if no
interface type was set. Instead, always set an interface type
explicitly.
Eventually we want to remove getType() altogether, and this
brings us one step closer to this goal.
Note that ParamDecls are excempt from this treatment, because
they don't have a proper interface type yet. Cleaning this up
requires more effort.
