Instead of returning empty type when RValue destination of the assignment
could not be determined, let's return it unresolved directly instead and
let it be handled by coerceToType, which is going to produce special expression
(UnresolvedTypeConversionExpression) which facilitates better diagnostics.
withoutActuallyEscaping has a signature like `<T..., U, V, W> (@nonescaping (T...) throws<U> -> V, (@escaping (T...) throws<U> -> V) -> W) -> W, but our type system for functions unfortunately isn't quite that expressive yet, so we need to special-case it. Set up the necessary type system when resolving an overload set to reference withoutActuallyEscaping, and if a type check succeeds, build a MakeTemporarilyEscapableExpr to represent it in the type-checked AST.
Previously, bridging conversions were handled as a form of "explicit
conversion" that was treated along the same path as normal
conversions in matchTypes(). Historically, this made some
sense---bridging was just another form of conversion---however, Swift
now separates out bridging into a different kind of conversion that is
available only via an explicit "as". This change accomplishes a few
things:
* Improves type inference around "as" coercions. We were incorrectly
inferring type variables of the "x" in "x as T" in cases where a
bridging conversion was expected, which cause some type inference
failures (e.g., the SR-3319 regression).
* Detangles checking for bridging conversions from other conversions,
so it's easier to isolate when we're applying a bridging
conversion.
* Explicitly handle optionals when dealing with bridging conversions,
addressing a number of problems with incorrect diagnostics, e.g.,
complains about "unrelated type" cast failures that would succeed at
runtime.
Addresses rdar://problem/29496775 / SR-3319 / SR-2365.
Follow the pattern set by isDictionaryType() of performing the query
and extracting the underlying key/element types directly. We often
need both regardless. NFC
Previously, validateDecl() would check if the declaration had an
interface type and use that as an indication not to proceed.
However for functions we can only set an interface type after
checking the generic signature, so a recursive call to validateDecl()
on a function would "steal" the outer call and complete validation.
For generic types, this meant we could have a declaration with a
valid interface type but no generic signature.
Both cases were problematic, so narrow workarounds were put in
place with additional new flags. This made the code harder to
reason about.
This patch consolidates the flags and establishes new invariants:
- If validateDecl() returns and the declaration has no interface
type and the isBeingValidated() flag is not set, it means one
of the parent contexts is being validated by an outer recursive
call.
- If validateDecl() returns and the declaration has the
isBeingValidated() flag set, it may or may not have an interface
type. In this case, the declaration itself is being validated
by an outer recursive call.
- If validateDecl() returns and the declaration has an interface
type and the isBeingValidated() flag is not set, it means the
declaration and all of its parent contexts are fully validated
and ready for use.
In general, we still want name lookup to find things that have an
interface type but are not in a valid generic context, so for this
reason nominal types and associated types get an interface type as
early as possible.
Most other code only wants to see fully formed decls, so a new
hasValidSignature() method returns true iff the interface type is
set and the isBeingValidated() flag is not set.
For example, while resolving a type, we can resolve an unqualified
reference to a nominal type without a valid signature. However, when
applying generic parameters, the hasValidSignature() flag is used
to ensure we error out instead of crashing if the generic signature
has not yet been formed.
- The DeclContext versions of these methods have equivalents
on the DeclContext class; use them instead.
- The GenericEnvironment versions of these methods are now
static methods on the GenericEnvironment class. Note that
these are not made redundant by the instance methods on
GenericEnvironment, since the static methods can also be
called with a null GenericEnvironment, in which case they
just assert that the type is fully concrete.
- Remove some unnecessary #includes of ArchetypeBuilder.h
and GenericEnvironment.h. Now changes to these files
result in a lot less recompilation.
Rename the old getMemberSubstitutions() to getContextSubstitutions()
and add a new getMemberSubstitutions() that takes a ValueDecl, rather
than the member's DeclContext.
This new method forwards generic parameters if the member is a generic
function.
Changes:
* Terminate all namespaces with the correct closing comment.
* Make sure argument names in comments match the corresponding parameter name.
* Remove redundant get() calls on smart pointers.
* Prefer using "override" or "final" instead of "virtual". Remove "virtual" where appropriate.
Once we've bound a type variable, we find those inactive constraints
that mention the type variable and make them active, so they'll be
simplified again. However, we weren't finding *all* constraints that
could be affected---in particular, we weren't searching everything
related to the type variables in the equivalence class, which meant
that some constraints would not get visited... and we would to
type-check simply because we didn't look at a constraint again when we
should have.
Fixes rdar://problem/29633747.
Update CSGen/CSApply/CSSolver to primarily use getType() from
ConstraintSystem.
Currently getType() just returns the type on the expression. As with
setType(), which continues to set the type on the expression, this
will be updated once all the other changes are in place.
This change also moves coerceToRValue from TypeChecker to
CosntraintSystem so that it can access the expression type map in the
constraint system.
I've been unable to reproduce the issue that hit on the builder, and
still expect this change to be NFC, so trying it out again. If it
fails, I'll revert again and try another shot at reproducing.
Original commit message:
We create new expressions that have the type on the expression
set. Make sure we capture these types in the constraint system type
map so that we can refer to types uniformally by consulting the map.
NFC.
(cherry picked from commit 57d5d974ff)
We create new expressions that have the type on the expression
set. Make sure we capture these types in the constraint system type
map so that we can refer to types uniformally by consulting the map.
NFC.
First, ensure all ParamDecls that are synthesized from scratch are given
both a contextual type and an interface type.
For ParamDecls written in source, add a new recordParamType() method to
GenericTypeResolver. This calls setType() or setInterfaceType() as
appropriate.
Interestingly enough a handful of diagnostics in the test suite have
improved. I'm not sure why, but I'll take it.
The ParamDecl::createUnboundSelf() method is now only used in the parser,
and no longer sets the type of the self parameter to the unbound generic
type. This was wrong anyway, since the type was always being overwritten.
This allows us to remove DeclContext::getSelfTypeOfContext().
Also, ensure that FuncDecl::getBodyResultTypeLoc() always has an interface
type for synthesized declarations, eliminating a mapTypeOutOfContext()
call when computing the function interface type in configureInterfaceType().
Finally, clean up the logic for resolving the DynamicSelfType. We now
get the interface or contextual type of 'Self' via the resolver, instead
of always getting the contextual type and patching it up inside
configureInterfaceType().
After recent changes, this asserts on all decls that are not VarDecls,
so we can just enforce that statically now. Interestingly, this turns
up some dead code which would have asserted immediately if called.
Also, replace AnyFunctionRef::getType() with
AnyFunctionRef::getInterfaceType(), since the old
AnyFunctionRef::getType() would just assert when called on
a Decl.
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>.
The ASTContext had a wacky "get member type" callback that actually
called back into the constraint system (!) to build member types. This
callback was obsoleted by the change that started representing nested
types as DependentMemberTypes.
It's possible some of the asserts will eventually migrate to something
like test-and-return, but at least for now let's ensure that we know
when this is happening.
This is not comprehensive. There are other places we are creating fresh
constraint systems and then creating constraints using type variables
from a pre-existing constraint systems.
[CodeCompletion] Using the default constraints generator for TupleExpr
when inferring the type of unresolved members. rdar://28991372
When code completing, we used to create a type variable to represent the type
of an entire tuple expression. However, recent improvements on parser make this
step unnecessary and crash-prone. Thus, we use the default constraint
generator to interpret tuple expressions.
When adding constraints into the constraint system, don't immediately
allocate a Constraint and add it via the most-general
addConstraint(). Instead, go through a more specific entrypoint (e.g.,
addValueMemberConstraint, addRestrictedConstraint, etc.), so we can
start phasing out the general "add an already-formed constraint"
function. NFC
The 'literalConformanceProto' field of
TypeVariableType::Implementation didn't take into account equivalence
classes of type variables. Eliminate it, and either look at the actual
expressions (for optimizing constraints during constraint generation)
or the actual constraints on a given type variable (for determining
whether to include optionals in the set of potential type variable
bindings).
(cherry picked from commit 6bdd9cfae5)
This reverts commit 6bdd9cfae5. This
commit *appears* to be breaking something in Dollar involving
inference with array literals and 'nil'; pull it back for more
investigation.
The 'literalConformanceProto' field of
TypeVariableType::Implementation didn't take into account equivalence
classes of type variables. Eliminate it, and either look at the actual
expressions (for optimizing constraints during constraint generation)
or the actual constraints on a given type variable (for determining
whether to include optionals in the set of potential type variable
bindings).
While, tracking defaulted constraints based on their type variable
usually works in practice, it can break if the type variable ends up
being equivalent to some other type variable that. Instead, record the
locators associated with Defaultable constraints where we used the
default, which are easier to work with during constraint application.
In most places where we were checking "is<ErrorType>()", we now mean
"any error occurred". The few exceptions are in associated type
inference, code completion, and expression diagnostics, where we might
still work with partial errors.
This particular flag should only be used in rare cases where we don't
want to know about failures, but instead want to get some
partially-formed type. Only very specific parts of the type checker
need this (associated type inference), and code completion relies on
it for slightly-better results.
When generating constraints for subscript convert InOutType into LValueType,
because base of the subscript should never be marked as inout, but rather as
@lvalue to denote mutability.
Resolves <rdar://problem/25601561>.
There was a ton of complicated logic here to work around
two problems:
- Same-type constraints were not represented properly in
RequirementReprs, requiring us to store them in strong form
and parse them out when printing type interfaces.
- The TypeBase::getAllGenericArgs() method did not do the
right thing for members of protocols and protocol extensions,
and so instead of simple calls to Type::subst(), we had
an elaborate 'ArchetypeTransformer' abstraction repeated
in two places.
Rewrite this code to use GenericSignatures and
GenericFunctionType instead of old-school GenericParamLists
and PolymorphicFunctionType.
This changes the code completion and AST printer output
slightly. A few of the changes are actually fixes for cases
where the old code didn't handle substitutions properly.
A few others are subjective, for example a generic parameter
list of the form <T : Proto> now prints as <T where T : Proto>.
We can add heuristics to make the output whatever we want
here; the important thing is that now we're using modern
abstractions.
The constraint generator's optimization to eagerly merge type
variables for different keys in a dictionary literal was too eager,
merging the type variables for (e.g.) a string literal and an integer
literal. This prevented us from properly inferring AnyHashable key
types in dictionary literals. Fixes the rest of rdar://problem/27661580.
The problem here is that we would just emit 'invalid pattern'
instead of digging deeper, which meant that the fix-it for
qualified enum element access wasn't getting inserted for
more complex patterns, such as 'case X(let x)'.
Unfortunately, in the matching_patterns.swift test, we emit
too many diagnostics that are not really useful to figuring
out the problem, and the old 'invalid pattern' made more
sense. I'll work on some CSDiag tweaks to address this --
I think it makes more sense to dig there than just emit a
general 'invalid pattern' diagnostic anyway.
Fixes <rdar://problem/27684266>.
