When a protocol closes off an associated type by tying it to a concrete
type (e.g., via a same-type constraint), allow associated type inference
to use that information to infer the associated type rather than
requiring the user to restate the obvious.
Fixes SR-6640.
During associated type inference, also look for default associated type
witnesses from overridden associated types, so that one need not
redeclare default associated types at every level in a protocol hierarchy.
When checking whether a particular protocol conformance satisfies all of
the protocol's requirements, we were suppressing substitution failures.
In some cases, this would mean that we marked a conformance "invalid"
without ever emitting a diagnostic, which would lead to downstream crashes.
Instead, treat substitution failures somewhat more lazily. If we encounter
one while performing the checking, put the conformance into a "delayed" list
rather than failing immediately. Teach the top-level type checking
loop to re-check these conformances, emitting a diagnostic if they
fail the second time around.
Fixes rdar://problem/35082483 and likely other issues that slipped
through the type checker or blew up in unpredictable ways.
Constructing a keypath expression that references a class member
needs to validate all other members of the class (or a protocol,
but I couldn't reproduce a crash with that case -- added a test
anyway).
Fixes <rdar://problem/36083061>.
Also remove mention of the word “contextual” type from the diagnostic
that rewrites array literals into dictionary literals and scale back
the scope of the diagnostic. This method was catching and
mis-diagnosing too many errors that could better be handled by invalid
conversion diagnostics.
Fix a silly error where we were returning the interface type of a type
declaration rather than the *declared* interface type, which meant we were
getting a metatype where we shouldn't.
Fixes rdar://problem/36003312.
The Swift class model does not support overriding declarations where either
the overridden declaration or the overriding declaration are in an extension.
However, the Objective-C class model does, so marking the declaration as
@objc (when possible) will work around the limitation.
Customize the "cannot override declaration in extension" diagnostic to
suggest adding @objc to the overridden declaration in cases where
@objc is permitted. Fixes SR-6512 / rdar://problem/35787914.
Code-completion of generic types expects to get a DeclContext for the
subscript, so make sure we recover well enough to produce a
SubscriptDecl.
rdar://35619175
This presents a regression in diagnostic quality that is definitely
worth it not to lie to SILGen about whether a switch is covered or not.
At the same time, disable SIL’s unreachable diagnostic for ‘default’
clauses which would previously cause a warning to be emitted if the
default was proven to be unreachable. This analysis is incomplete
anyways and can be done by Sema in the future if we desire.
The Space Engine includes a heuristic that attempted a combinatorics-
based check to see if a pattern covered an insufficient amount of cases.
In straight-line switches this avoided computing a subspace match that
would have been quite expensive computationally. However, when
expressive patterns (like tuple patterns) are used, it can fool the
check because the covered space is much larger than the actual size of
the space due to pattern overlap that counting like this simply can't detect.
Instead, just do the right thing and perform a space subtraction after
the existing preconditions for the heuristic are satisfied.
Resolves SR-6316
Move the rest of associated type inference into the new source file,
and split RequirementEnvironment into its own AST-level header, because it
can be re-used and has no ties to the type checker.
Follow-up for 7c707ce97c. Without this, the declaration would be
accepted, but any uses of the overridden property would be treated as
ambiguous because the property wouldn't really be marked as an
override.
rdar://problem/35900345
Otherwise, we'll never get a chance to drain the TypeChecker's
UsedConformances list.
Fixes <https://bugs.swift.org/browse/SR-6565>, <rdar://problem/35949729>.
Be consistent with CoerceExpr and for the constraint we create use the
locator from the result of the expression rather than the locator from
the source of the expression.
Move associated type inference into its own class, to make this
code easier to understand/maintain/improve. Minor diagnostics changes
because we're properly passing uninference associated type declarations
to the "group" checker.
This is a corner case but would previously lead to a compiler crash
or miscompile.
Fixes <rdar://problem/21991470>, <https://bugs.swift.org/browse/SR-5022>.
Within the where clause of (e.g.) an extension, unqualified name lookup is
permitted to find associated types. Extend this to also include finding
typealiases declared within the protocol itself.
This is service of the IndexDistance change (SE-0191), and
fixes rdar://problem/35490504.
Previous versions of Swift accidentally treated lazy properties as
computed properties because of how they were implemented. Now that we
check this correctly, we've broken source compatibility. Downgrade the
error to a warning in this case.
(Arguably we could /allow/ overriding with a stored property. The
original concerns were that you could accidentally end up with extra
storage you didn't need, and that observing accessors would behave
differently based on whether or not the property was overriding. But
there's at least no ambiguity for 'lazy', which can't have observing
accessors today.)
rdar://problem/35870371
