To summarize the theory based on
`validation-test/Evolution/test_protocol_add_reparented.swift`:
1. Two extensions on MultiParent share the mangled name
$s23protocol_add_reparented11MultiParentPAAEMXE for their context descriptor
2. The first extension to be emitted creates a GlobalVariable with type
TypeContextDescriptorTy (forward decl)
3. The second extension finds it in getAddrOfSharedContextDescriptor via
Module.getGlobalVariable() and inserts the same pointer in GlobalVars
4. When the first extension's descriptor gets defined, getAddrOfLLVMVariable
creates a new GlobalVariable and erases the old one.
5. The second extension's GlobalVars entry is now a dangling pointer, as the
act of defining it for the first extension definition didn't update the map.
This patch does seem to fix the dangling pointer, though there is probably
a better way to fix the underlying bad ordering of events.
Ordinary base protocols use fixed-indexing to access the base index.
That means adding another base protocol to an existing protocol
can break the order of the entries, and thus clients, because we
otherwise order the base entires with TypeDecl::compare.
Reparentable protocols are meant to be resilient to that, so we
order them at the end of the base entries list, just before the
other resilient entries in the witness table.
This patch completes the picture, by having the reparentable
protocol entries be indexed resiliently, in the same manner as
associated conformances.
The difference is that we can skip the call to
`swift_getAssociatedConformanceWitness`
and compute the index directly by finding the distance of the
descriptors, because we know all base protocol witness table
entries are eagarly instantiated.
Using this distance protects us from the ordering problems
of entries among all of the reparentable base protocols.
resolves rdar://173409851
Support for existentials in Embedded Swift has been available for a
little while now and appears to be solid. Remove the ability to disable
them (via `-disable-experimental-feature EmbeddedExistentials`), both
because it simplifies the code and because it's an ABI break to
disable the feature.
Given that we implicitly expanded Copyable & Escapable
conformance requirements for suppressed primary associated
types, we now need this function to do the opposite;
filtering Copyable & Escapable requirements on such primary
associated types and adding inverses if those requirements
are missing.
This function plays a crucial role in emitting the interface
files accurately for functions and types, in addition to
how we mangle generic signatures into function symbols.
The mangling for generic signatures under the -WithDefaults version of
suppressed associated types goes like this:
- primary associated type T.A has an inverse `Rj` or `RJ` mangled
into the generic signature if it lacks the conformance, or
nothing is mangled into it.
- non-primary associated type T.B has either a `T.B: Copyable`
requirement mangled into it, or nothing is mangled into it.
For the legacy SuppressedAssociatedTypes feature, where there's no
defaults, it uses the "non-primary assocated type" mangling strategy
for all generic signatures.
This change forces you to write ``@reparented` relationships
on an extension of a protocol, rather than on the protocol
itself.
The ProtocolConformance needs to be associated with some
GenericContext and IRGen expects it to be an ExtensionDecl.
That environment defines under what conditions the conformance
exists. We also need to define witnesses for the new parent's
requirements in an extension anyway, so it's a natural fit.
The previous workaround for this was kind of awful, as it'd
require searching all the protocol's extensions and "guess"
which extension they want to represent the conformance. While
we could try to synthesize an extension, there's two
challenges there:
1. Due to SuppressedAssociatedTypes, it's not so simple to
synthesize an unconstrained ExtensionDecl.
2. We currently rely on same-type requirements to pin the
associated types to particular witnesses of those requirements
in the extension. So it's not purely unconstrained! For example,
```
extension Seq: @reparented BorrowSeq where Iter == MyIter {}
```
The constraints that are disallowed (but not yet diagnosed)
are conditional conformance requirements, as the default
conformance for a reparenting cannot depend on those.
Thus, it's better that programmers to specify the extension.
`irgen::addGenericRequirements` will later filter out Copyable
and Escapable requirements, so this field's count isn't accurate
if it's using the pre-filtered number.
This should in theory only affect the metadata emission for keypaths,
specifically, the caller `IRGenModule::getAddrOfKeyPathPattern`.
If you had something like:
struct G<T> {
func f<each U>(_: repeat each U) where T == (repeat each U) {}
}
We would fulfill 'each U' from the metadata for 'G<(repeat each U)>',
by taking apart the tuple metadata for `(repeat each U)` and forming
a pack.
However this code path was only intended to kick in for a tuple
conformance witness thunk. In the general case, this optimization
is not correct, because if 'each U' is substituted with a
one-element pack, the generic argument of `G<(repeat each U)>` is
just that one element's metadata, and not a tuple. In fact, we
cannot distinguish the one-element tuple case, because the wrapped
element may itself be a tuple.
The fix is to just split off FulfillmentMap::searchTupleTypeMetadata()
from searchTypeMetadata(), and only call the former when we're in
the specific situation that requires it.
- Fixes https://github.com/swiftlang/swift/issues/78191.
- Fixes rdar://problem/135325886.
This changes the isIsolatingCurrentContext function to return `Bool?`
and removes all the witness table trickery we did previously to detect
if it was implemented or not. This comes at a cost of trying to invoke
it always, before `checkIsolated`, but it makes for an simpler
implementation and more checkable even by third party Swift code which
may want to ask this question.
Along with the `withSerialExecutor` function, this now enables us to
check the isolation at runtime when we have an `any Actor` e.g. from
`#isolation`.
Updates SE-0471 according to
https://forums.swift.org/t/se-0471-improved-custom-serialexecutor-isolation-checking-for-concurrency-runtime/78834/
review discussions
Store specialize witness tables in a separate lookup table in the module. This allows that for a normal conformance there can exist the original _and_ a specialized witness table.
Also, add a boolean property `isSpecialized` to `WitnessTable` which indicates whether the witness table is specialized or not.
This corrects how we were dealing with dispatch thunks -- mostly be
removing a lot of special casing we did but doesn't seem necessary and
instead we correct and emit all the necessary information int TBD.
This builds on https://github.com/swiftlang/swift/pull/74935 by further refining how we fixed that issue, and adds more regression tests. It also removes a load of special casing of distributed thunks in library evolution mode, which is great.
Resolves and adds regression test for for rdar://145292018
This is also a more proper fix to the previously resolved but in a not-great-way which caused other issues:
- resolves rdar://128284016
- resolves rdar://128310903
This fixes a regression from a00157ec43.
My change made it so that sourceKey.Kind was checked after being
overwritten with an abstract conformance, so we would never take
the if statement. Incredibly, it almost worked.
Fixes rdar://problem/148698142.
An "abstract" ProtocolConformanceRef is a conformance of a type
parameter or archetype to a given protocol. Previously, we would only
store the protocol requirement itself---but not track the actual
conforming type, requiring clients of ProtocolConformanceRef to keep
track of this information separately.
Record the conforming type as part of an abstract ProtocolConformanceRef,
so that clients will be able to recover it later. This is handled by a uniqued
AbstractConformance structure, so that ProtocolConformanceRef itself stays one
pointer.
There remain a small number of places where we create an abstract
ProtocolConformanceRef with a null type. We'll want to chip away at
those and establish some stronger invariants on the abstract conformance
in the future.
The Protocol field isn't really necessary, because the conformance
stores the protocol. But we do need the substituted subject type
of the requirement, just temporarily, until an abstract conformance
stores its own subject type too.
The "abstract conformance is just a ProtocolDecl" assumption is pretty
fundamental here, so we have to fudge a bit at the API boundary for now.
Eventually, LocalTypeDataKind should just contain a ProtocolConformanceRef
instead of duplicating the representation, however this would require
fixing various calls to LocalTypeDataKind::forAbstractProtocolWitnessTable()
which pass in a ProtocolDecl to pass in a ProtocolConformanceRef instead.
* [Concurrency] Detect non-default impls of isIsolatingCurrentContext
* [Concurrency] No need for trailing info about isIsolating... in conformance
* Apply changes from review
The NormalProtocolConformance APIs for checking for an explicitly-written
isolation on a conformance were easy to get to, and the real semantic
API was buried in the type checker, leading to some unprincipled
checking. Instead, create a central ProtocolConformance::getIsolation()
to get the (semantic) actor isolation, and let that be the only place
that will access the explicitly-written global actor isolation for a
conformance. Update all call sites appropriately.
Instead of using the `isolated P` syntax, switch to specifying the
global actor type directly, e.g.,
class MyClass: @MainActor MyProto { ... }
No functionality change at this point
When creating a specialized witness table, we need to get the right specialized conformance.
In IRGen don't emit associated conformance witness table entries if the protocol is not a class protocol.
In this case the associated type can never be used to create an existential. Therefore such a witness table entry is never used at runtime in embedded swift.
Fixes a compiler crash
rdar://146448091
Doug Gregor
Kavon Farvardin
Erik Eckstein
Dario Rexin
Arnold Schwaighofer
Slava Pestov
Anthony Latsis
John McCall
Konrad 'ktoso' Malawski
Nate Chandler
Jeff