Now covers following new areas (alongside simple assignments):
- Contextual type coercions:
- In assignment e.g. `let _: X = foo`
- In return type positions e.g. `func foo() -> A { return bar }`
- Argument-to-parameter applications (including @autoclosure)
Escapingness is a property of the type of a value, not a property of a function
parameter. Having it as a separate parameter flag just meant one more piece of
state that could get out of sync and cause weird problems.
Instead, always look at the noescape bit in a function type as the canonical
source of truth.
This does mean that '@escaping' is now printed in a few diagnostics where it was
not printed before; we can investigate these as separate issues, but it is
correct to print it there because the function types in question are, in fact,
escaping.
Fixes <https://bugs.swift.org/browse/SR-10256>, <rdar://problem/49522774>.
There are cases where SE-0110 allows tuple splatting behavior,
so to aid diagnostics let's use a new type variable to represent
a tuple type formed from existing arguments instead of imploding
them directly.
12a65fffee restricted tuple splat
to a single tuple or type variable parameter, but it has to
support dependent member types as well because they could be
resolved to `Void` (or empty tuple).
Resolves: rdar://problem/48443263
Try to fix constraint system in a way where member
reference is going to be defined in terms of its use,
which makes it seem like parameters match arguments
exactly. Such helps to produce solutions and diagnose
failures related to missing members precisely.
These changes would be further extended to diagnose use
of unavailable members and other structural member failures.
Resolves: rdar://problem/34583132
Resolves: rdar://problem/36989788
Resolved: rdar://problem/39586166
Resolves: rdar://problem/40537782
Resolves: rdar://problem/46211109
When the compiler fails to find an overload with suitable parameter or return types, it often attaches a note listing the available overloads so that users can find the one they meant to use. The overloads are currently ordered in a way that depends on the order they were declared, so swift-evolve would sometimes cause tests involving these diagnostics to fail.
This change emits the list in a textually-sorted order instead. The names were already being sorted as they were inserted into a std::set, so this shouldn’t significantly slow down the diagnostic.
While trying to lookup member reference on some base type, handle
base being an `InOutType`, which could be a result of previous
sub-expression re-typechecks made by diagnostics.
Resolves: rdar://problem/45771997
When `bind param` constraint is associated with a given
type variable a set of bindings collected for it is
potentially incomplete, because binding gathering doesn't
look through related type variables. Which means that
such type variable has to be de-prioritized until
`bind param` constraint is resolved or there is just
nothing else to try, otherwise there is a risk that
solver would skip some of the valid solutions.
This only affects type variable that appears one the
right-hand side of the `bind param` constraint and
represents result type of the closure body, because
left-hand side gets types from overload choices.
Resolves: rdar://problem/45659733
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
When `bind param` constraint is associated with a given type
variable a set of bindings collected for it is potentially
incomplete, because binding gathering doesn't look through related
type variables. Which means that such type variable has to be
de-prioritized until `bind param` constraint is resolved
or there is just nothing else to try, otherwise there is a
risk that solver would skip some of the valid solutions.
Resolves: rdar://problem/45659733
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
Replace the last (and most obscure) use of the poor “use ‘?’ or ‘!’” diagnostic with the
new, more explanatory version that provides separate notes with Fix-Its for coalescing or
force-unwrapping the value.
Finishes rdar://problem/42081852.
When we type check a closure expression with inferred parameter
types, we assign type variables to them. If type checking fails,
we end up in FailureDiagnosis::diagnoseClosureExpr().
If there was no contextual type, we would skip the code path
which nukes type variables in the closure's ParamDecls before
proceeding to type check the body. Type checking of the body
creates a new constraint system which would pick up the outer
constraint system's type variables and blow up.
Fixes <rdar://problem/39489003>.
If we could find a binding for type variable representing closure result
let's also add implicit `Void` type as another pontential binding to attempt
because there is an implicit conversion from `() -> T` to `() -> Void`
so finding `Void` early is going to help avoid function conversions down
the line.
Resolves: rdar://problem/37790062
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
Currently edge related to the parameter bindings is contracted
without properly checking if newly created equivalence class has
the same inout & l-value requirements. This patch improves the
situation by disallowing contraction of the edges related to parameter
binding constraint where left-hand side has `inout` attribute set.
Such guarantees that parameter can get `inout` type assigned when
argument gets `l-value` type.
Resolves: rdar://problem/33429010
Since we no longer allow constraction of subtype constraints, workaround
which exists in `matchTypes`, for situations where left-hand side of such
constraint is going to be wrapped in `inout` type, is no longer required.
Resolves: rdar://problem/34137342, rdar://problem/34136625
Split out the things that are really specific to Swift 3 into a new
closures_swift3.swift.
In the process I found that two things that should compile without error
under -swift-version 4 do not, so those tests are currently in
closures_swift3.swift and I have opened new bugs for the issues:
https://bugs.swift.org/browse/SR-5791https://bugs.swift.org/browse/SR-5792
If we allow the right-hand type to be bound first, it can artificially
limit the options for the left-hand side, so attempt to delay binding of
the right-hand side types until after we've chosen something for the
left-hand side.
The test here will not fail without this change, but will fail without
this change if the ConstraintGraph.cpp changes from @xedin's edge
contraction patch (https://github.com/apple/swift/pull/11118) are
applied.
In diagnoseUnintendedOptionalBehavior, guard against recursing into
non-single-expression closures. If we recurse into these, we can end
up hitting malformed ASTs that we do not expect. These happen when we
successfully type-check the code outside of the closure, but the
closure body has errors.
There are potentially other similar issues in other miscellaneous
diagnostics walks.
I opened https://bugs.swift.org/browse/SR-5758 to remind us to review
these and ensure they do not have similar issues.
Previously, the failure diagnosis visitor would
default to the generic expr walk which would wind
up type checking the closure body and calling it a day.
Walk into the closure of a capture list expression to
emit better diagnostics.
A regression test for SR-5747 is added.
