When trying to convert tuple type to existential look through
it's elements and convert found LValues to RValues (via load)
before applying erasure.
Resolves: <rdar://problem/27575060>.
It is possible to have requirement environments in which substitution
of the conforming type for Self into the requirement's signature would
result in substituted same-type requirements that no longer involve
type parameters. This triggered an assertion in the construction of
the requiremet environement; instead, just drop the requirement
because it is no longer interesting. Witness matching will simply fail
later one.
With this fix, it now because possible to add generic requirements to
a protocol that were unsatisfiable for certain models. For example,
the following protocol:
protocol P {
associatedtype A
associatedtype B
func f<T: P>(_: T) where T.A == Self.A, T.A == Self.B
}
can only be satisfied by conforming types for which Self.A ==
Self.B. SE-0142 will introduce a proper way to add such requirements
onto associated types. This commit makes any such attempt to add
requirements onto "Self" (or its associated types) ill-formed, so we
will reject the protocol P above with a diagnostic such as:
error: instance method requirement 'f' cannot add constraint
'Self.A == Self.B' on 'Self'
Fixes rdar://problem/29075927.
When cast expressions (conditional or forced downcasts) are part
of the closure expression with invalid parameters or return type,
they are not going be to folded by PreCheckExpression, which means
that they are not going to have sub-expression (from) set.
Resolves: <rdar://problem/27464577>.
Disallows solutions containing free type variables on the final step of
witness matching, because that would yield incorrect results when witness
type has free type variables as well.
Resolves: <rdar://problem/27249691>.
Modify TypeChecker::coerceParameterListToType to always validate and consider only
valid contextual types (contains: no undefined, error, or type variables etc.) for
argument type coercion, such logic prevents erasure of important explicitly specified
type information attached to parameters of the closure expressions being diagnosed.
Resolves: SR-2994.
In the constraint solver, we've traditionally modeled nested type via
a "type member" constraint of the form
$T1 = $T0.NameOfTypeMember
and treated $T1 as a type variable. While the solver did generally try
to avoid attempting bindings for $T1 (it would wait until $T0 was
bound, which solves the constraint), on occasion we would get weird
behavior because the solver did try to bind the type
variable.
With this commit, model nested types via DependentMemberType, the same
way we handle (e.g.) the nested type of a generic type parameter. This
solution maintains more information (e.g., we know specifically which
associated type we're referring to), fits in better with the type
system (we know how to deal with dependent members throughout the type
checker, AST, and so on), and is easier to reason able.
This change is a performance optimization for the type checker for a
few reasons. First, it reduces the number of type variables we need to
deal with significantly (we create half as many type variables while
type checking the standard library), and the solver scales poorly with
the number of type variables because it visits all of the
as-yet-unbound type variables at each solving step. Second, it
eliminates a number of redundant by-name lookups in cases where we
already know which associated type we want.
Overall, this change provides a 25% speedup when type-checking the
standard library.
In cases where we cannot infer the types they won't be, so we don't want
to just cast to BoundGenericType when we see these.
Fixes rdar://problem/28317710 and at least one dup (and I think a few
more).
When a constraint fails, we retire it... but we also need to remove it
from the constraint graph. Otherwise, we break invariants when
diagnostic generation attempts to continue simplification.
Fixes rdar://rdar28145033.
When performing the occurs check, look for the *representative* of the
type variable we're about to bind, rather than the type variable
itself. Fixes rdar://problem/26845038, SR-1512, SR-1902, SR2635,
SR-2852, and SR-2766.
We've been performing the "occurs" check when computing potential
bindings for type variables, but we weren't actually performing the
check for bindings that *must* occur. Perform the occurs check before
binding type variables, which fixes a few crashers and is far more principled.
Note that this obviates the need for tracking the type variables we've
substituted in simplifyType(), so simplify that as well.
Fixes rdar://problem/27879334 / SR-2351.
We had a few places that were performing ad hoc variants of
ConstraintSystem::getFixedTypeRecursive(); simplify it's interface so
we can use it everywhere consistently. Fixes rdar://problem/27261929.
We were attempting to clean up stray type variables before creating a
new constraint system and moving forward with narrowing down the
typecheck failure, but we were failing to remove type variables for
interpolated strings.
Fix that, as well as removing them from TypeExpr's, and add an assert
that on exit from the pre-order visitor we don't have any type
variables (except for literals that aren't interpolated strings, which
I'm going to dig into further).
Fixes rdar://problem/27830834 and SR-2716.
Fully-qualified references to associated types in parameter lists of
constructors could result in infinite recursion and crash the compiler
when the typealias for the associated type is not defined.
Use the same approach used in normal function parameter lists of setting
IsBeingTypeChecked on the enclosing type to avoid going into an infinite
recursion here.
Resolves rdar://problem/27680407.
Add minimized test for rdar://problem/27830834.
In a build with asserts enabled assert with:
(TypeVariables[impl.getGraphIndex()] == typeVar && "Type variable mismatch")
Add minimized tests for:
rdar://problem/27464577
rdar://problem/27575060
rdar://problem/27680407
rdar://problem/27787341
rdar://problem/27815848
As these (and other tests added here) are fixed, we can move them into a
new type_checker_crashers_fixed directory.
