Normally there is very little the type checker can conclude about
casts between existentials, because new conformances can be added
retroactively. However if the existentials are class-constrained,
we can rule out certain casts as always failing by looking at
superclass bounds.
NormalProtocolConformance has the only correct implementation of this
functionality. Instead, providing a safer getWitnessDecl() that
doesn't promise substitutions that are incorrect (and not actually
used by any clients).
We don't finalize declarations when there's been an error, which means
we might never assign types to the stored properties/cases of a nominal
type from another file, which means that circularity checking for types
using those types be re-delayed.
Fixes SR-4594.
Rather than detecting recursion and bailing early, delay requirements
that would form recursive types. Note that we aren't actually
processing them later.
Looks like subscript validation wasn't checking or setting
ValueDecl::isBeingValidated(). This caused a stack overflow
with associated type inference. The way to trigger this
during normal use is to invoke the fixit for adding
missing protocol requirements -- they're written in terms
of the protocol's associated type, which the user might
not have defined yet.
Fixes <rdar://problem/26680599>.
The Swift 4 Migrator is invoked through either the driver and frontend
with the -update-code flag.
The basic pipeline in the frontend is:
- Perform some list of syntactic fixes (there are currently none).
- Perform N rounds of sema fix-its on the primary input file, currently
set to 7 based on prior migrator seasons. Right now, this is just set
to take any fix-it suggested by the compiler.
- Emit a replacement map file, a JSON file describing replacements to a
file that Xcode knows how to understand.
Currently, the Migrator maintains a history of migration states along
the way for debugging purposes.
- Add -emit-remap frontend option
This will indicate the EmitRemap frontend action.
- Don't fork to a separte swift-update binary.
This is going to be a mode of the compiler, invoked by the same flags.
- Add -disable-migrator-fixits option
Useful for debugging, this skips the phase in the Migrator that
automatically applies fix-its suggested by the compiler.
- Add -emit-migrated-file-path option
This is used for testing/debugging scenarios. This takes the final
migration state's output text and writes it to the file specified
by this option.
- Add -dump-migration-states-dir
This dumps all of the migration states encountered during a migration
run for a file to the given directory. For example, the compiler
fix-it migration pass dumps the input file, the output file, and the
remap file between the two.
State output has the following naming convention:
${Index}-${MigrationPassName}-${What}.${extension}, such as:
1-FixitMigrationState-Input.swift
rdar://problem/30926261
We use simplifyConstraint() to activate other constraints, and then
examine those constraints to find related disjunctions. In examining
those active constraints, we were simplifying them in case they
failed (which would allow us to bail out earlier). In doing so, we could
potentially generate new disjunctions when we simplify an unresolved
value member constraint. If we do that, we end up collecting these new
disjunctions as part of the set of related disjunctions, but that's
problematic because as part of exiting the solver scope to roll back
changes we delete these disjunctions from the system.
Instead of actually simplifying the active constraints, just collect the
disjunctions and move the active constraints back to the inactive list.
With this change we can build the stdlib.
Rather than hardcoding all of the substitution logic for requirements
in the RequirementEnvironment constructor, harden and re-use the
GenericSignatureBuilder's substitution logic instead.
When a requirement mentions a concrete type, that type might utter
other types (e.g., Set<T>) that infer requirements (here, T:
Hashable). Perform requirement inference for such types.
Part of rdar://problem/31520386.
We have various hacks in the constraint solver to improve the
compile-time performance characteristics of operators. Some of those
didn't respect availability annotations, causing us to incorrectly
choose an unavailable operator when available options exist.
Fixes rdar://problem/31592529.
@IBInspectable and @GKInspectable both work via the Objective-C
runtime. SE-0160 made them imply @objc, but doing so made it an error
to define an @IBInspectable or @GKInspectable property with a type
that could not be expressed in Objective-C. The attribute is useless,
but this broke Swift 3 code.
So, downgrade the error to a warning in Swift 3 compatibility mode,
with a Fix-It to remove the useless attribute. It remains an error in
Swift 4.
Fixes rdar://problem/31408971.
There were various problems with layout constraints either
being ignored or handled incorrectly. Now that I've exercised
this support with an upcoming patch, there are some fixes
here.
Also, introduce a new ExistentialLayout::getLayoutConstriant()
which returns a value for existentials which are class-constrained
but don't have a superclass or any class-constrained protocols;
an example would be AnyObject, or AnyObject & P for some
non-class protocol P.
NFC for now, since these layout-constrained existentials cannot
be constructed yet.
Add a 'hasExplicitAnyObject()' bit to ProtocolCompositionType
to represent canonical composition types containing '& AnyObject'.
Serialize this bit and take it into account when building
ExistentialLayouts.
Rename ProtocolCompositionType::getProtocols() to getMembers()
since it can contain classes now, and update a few usages that
need further attention with FIXMEs or asserts.
For now, nothing actually constructs these types, and they will
trigger arounds asserts. Upcoming patches will introduce support
for this.
ExistentialLayout::getProtocols() can return an interior
pointer if the layout describes a single protocol type.
In this case we must not hold on to the result after
the layout goes out of scope.
Fix a few places where this was happening, which should
address a test failure we've been seeing.
Fixes <rdar://problem/31586433>.
