solve() is a bit too overloaded, so rename the version that does the
core "evaluate all of the steps to produce a set of solutions"
functionality to solveImpl().
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.
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.
Diagnose ephemeral conversions that are passed to @_nonEphemeral
parameters. Currently, this defaults to a warning with a frontend flag
to upgrade to an error. Hopefully this will become an error by default
in a future language version.
Patch up all the places that are making a syntactic judgement about the
isInvalid() bit in a ValueDecl. They may continue to use that query,
but most guard themselves on whether the interface type has been set.
ProtocolConformanceRef already has an invalid state. Drop all of the
uses of Optional<ProtocolConformanceRef> and just use
ProtocolConformanceRef::forInvalid() to represent it. Mechanically
translate all of the callers and callsites to use this new
representation.
"Condition" path element is used to represent a condition expression
associated with `if` expression or ternary operator `? :`.
Locator has been changed in the way that it's now anchored from `if`
itself which simplifies down to condition expression it needed.
Extend #27668 by declining to validate the type of variables
bound by a pattern binding initializer when computing an effective
overload type while rooted at that initializer.
Inline the interface type reset into its callers and make sure they're
also setting the invalid bit - which this was not doing before.
Unfortunately, this is not enough to be able to simplify any part of var
decl validation.
Currently absence of `subtyping` is the only problem detected and diagnosed specifically
for `inout` parameters, but there could be type mismatches in `inout` positions as well
and we can use `argument-to-parameter mismatch fix to detect and diagnose them.
Structurally prevent a number of common anti-patterns involving generic
signatures by separating the interface into GenericSignature and the
implementation into GenericSignatureBase. In particular, this allows
the comparison operators to be deleted which forces callers to
canonicalize the signature or ask to compare pointers explicitly.
Now that the generic signature is computable on demand, this predicate is doubly useless. All of the callers intended to ask "hasInterfaceType" anyways.
Computing the generic signature changes the way that cycles appear in the compiler. For now, break these cycles. We should investigate each place where hasComputedGenericSignature() is used in service of breaking cycles. See rdar://55263708
