doesn't conform to the associatedtype's protocol (only in diagnostic mode).
This allows the solver to find solutions for more cases involving requirement
failures for dependent member types without special cases across the solver
that check for dependent member types with no type variables.
Just like in cases where both sides are dependent member types
with resolved base that can't be simplified to a concrete type
let's ignore this mismatch and mark affected type variable as a hole
because something else has to be fixed already for this to happen.
all cases of missing generic parameters.
In `ComponentStep::take` when there are no bindings or disjunctions, use hole
propagation to default remaining free type variables that aren't for generic
parameters and continue solving. Rather than using a defaultable constraint for
holes, assign a fixed type directly when we have no bindings to try.
We were building the following constraint, where $member and
$input are type variables and 'result' is a concrete type:
- Conversion($member, $input -> result)
When $member was fixed to a function type of arbitrary
arity, this would simplify to a conversion between $member's
result type and 'result'.
Instead, express this using the newly-added FunctionResult
constraint:
- FunctionResult($member, $result)
- Conversion($result, result)
I wasn't expecting this to change diagnostics, but it looks
like it did; I'm not going to bother investigating why,
because Pavel is going to rewrite contextual diagnostics soon
anyway. All but one are clear improvements.
Fixes <rdar://41416346> and <rdar://41416647>, two cases where
diagnostics regressed from -swift-version 3 to -swift-version 4.
We are currently in process of removing `InOutType`
so `VarDecl::get{Interface}Type` is going to wrap base
type into `InOutType` if its flag indicates that it's
an `inout` parameter declaration. But such type can't
be restored directly using `VarDecl::set{Interface}Type`
caller needs additional logic to extract base type.
Resolves: rdar://problem/33613329
