Replace two prominent uses of SubstitutionList, in ConcreteDeclRef and
Witness, with SubstitutionMap. Deal with the myriad places where we
now have substitution maps and need substitution lists (or vice versa)
caused by this change.
Overall, removes ~50 explicit uses of SubstitutionList (of ~400).
Convert NameAliasType’s internal representation from tail-allocating an
array of Substitutions (to be treated as a SubstitutionList) to store a
single SubstitutionMap. Serialize using that SubstitutionMap.
Allow substitution maps to be serialized directly (via an ID), writing out
the replacement types and conformances as appropriate. This is a more
efficient form of serialization than the current SubstitutionList approach,
because it maintains uniqueness of substitution maps within a module file,
and is a step toward eliminating SubstitutionList entirely.
Avoid storing more information than necessary in witnesses
and establishing the invariant that we only use out-of-line
storage when we require substitutions.
Absence of synthetic generic environment should not affect
serialization of the required substitutions because they can
come from outer requirement context for static members.
Resolves: rdar://problem/36497404
We should always go through the Clang importer to reinstantiate them. Serializing them leads to the possibility of us ending up with multiple conformances with different identities that ought to be equivalent.
We should always go through the Clang importer to reinstantiate them. Serializing them leads to the possibility of us ending up with multiple conformances with different identities that ought to be equivalent.
We still use the old layout for NameAliasType for builtin types, so
rename the Layout struct and corresponding code to describe its new
(more restricted) purpose.
Rather than relying on the NameAliasType we get by default for references
to non-generic typealiases, use BoundNameAliasType consistently to handle
references to typealiases that are formed by the type checker.
This doesn't have a specific effect now, because all of these places
are likely to only see NameAliasType, but it is refactoring with the
intent of eliminating NameAliasType entirely.
Introduce a new Type node, BoundNameAliasType, which describes a
reference to a typealias that requires substitutions to produce the
underlying type. This new type node is used both for references to
generic typealiases and for references to (non-generic) typealiases
that occur within generic contexts, e.g., Array<Int>.Element.
At present, the new type node is mainly useful in preserving type
sugar for diagnostics purposes, as well as being reflected in other
tools (indexing, code completion, etc.). The intent is to completely
replace NameAliasType in the future.
We have a predicate in ClassDecl, 'inheritsSuperclassInitializers',
that is used in a few places to decide if we need to do lookups into a
superclass to find all relevant initializers. That's useful, but the
actual work being computed in that function is almost identical to the
work done in figuring out whether the class has provided all its
superclass's /required/ initializers, which is part of the type
checker operation 'resolveImplicitConstructors'. Furthermore,
'inheritsSuperclassInitializers' is /already/ calling
'resolveImplicitConstructors' because those implicit constructors
might affect the result.
Simplify this whole mess and prevent further inconsistencies like the
previous commit by just making 'resolveImplicitConstructors' decide
whether superclass convenience initializers are inherited. It does
make that function more complicated, but with the benefit of not
having duplication anymore.
No intended user-visible change, except that this bit is now
serialized instead of being recomputed, which means the module format
changed.
Previously this just relied on serialization::VarDeclSpecifier being
identical to swift::VarDecl::Specifier, which is presumably true, but
also fragile.
An over-eager assertion in ModuleFile::maybeReadGenericParams() rejected
deserialization into the context of a generic subscript for a generic
parameter within one of its accessors. Weaken the assertion; the
DeclContext of the generic parameter will be overwritten with the
correct context later.
Fixes rdar://problem/37408205.
We can encounter these when the compiler modifies an inlinable
function to break apart a struct and the struct uses a private
type for one of its fields. It's questionable whether we /should/
handle this, but meanwhile this /is/ a non-intrusive fix that
preserves the performance of non-resilient libraries.
(That is, it appears this worked in Swift 4.0, though perhaps
not all of the same optimizations kicked in.)
https://bugs.swift.org/browse/SR-6874
Also remove the decl from the known decls and remove a
bunch of code referencing that decl as well as a bunch of other
random things including deserialization support.
This includes removing some specialized diagnostics code that
matched the identifier ImplicitlyUnwrappedOptional, and tweaking
diagnostics for various modes and various issues.
Fixes most of rdar://problem/37121121, among other things.
This has three principal advantages:
- It gives some additional type-safety when working
with known accessors.
- It makes it significantly easier to test whether a declaration
is an accessor and encourages the use of a common idiom.
- It saves a small amount of memory in both FuncDecl and its
serialized form.
The deserialization of the type witnesses for a normal protocol conformance
is crucial to the usability of said conformance. Deserializing the
value witnesses first can fail if they somehow rely on the type
witnesses (e.g., through a recursive conformance).
As a stop-gap, deserialize and record type witnesses *first*, then
deserialize value witnesses afterward. A longer-term solution would
make deserialization of the normal protocol conformance far more
lazy.
Fixes SR-6522 / rdar://problem/35830641, a merge-modules crasher in a
nontrivial project.
We would miscompile in mixed-language-version projects when a Swift class was compiled for one language version, while using Objective-C-imported types that are only available to that version, and then imported into a Swift module with a different language version that wasn't able to see all of the properties because of incompatible imported types. This manifested in a number of ways:
- We assumed we could re-derive the constant field offsets of the class's ivars from the layout, which is wrong if properties are missing, causing accesses to final properties or subclass properties to go to the wrong offsets.
- We assumed we could re-derive the instance size and alignment of a class instance in total, causing code to allocate the wrong amount of memory.
- We neglected to account for the space that stored properties take up in the field offset vector of the class object, causing us to load vtable entries for following subclass methods from the wrong offsets.
Eventually, resilience should reduce our exposure to these kinds of problems. As an incremental step in the right direction, when we look at a class from another module in IRGen, treat it as always variably-sized, so we don't try to hardcode offsets, size, or alignment of its instances. When we import a class, and we're unable to import a stored property, leave behind a new kind of MissingMemberDecl that records the number of field offset vector slots it will take up, so that we lay out subclass objects and compute vtable offsets correctly. Fixes rdar://problem/35330067.
A side effect of this is that the RemoteAST library is no longer able to provide fixed field offsets for class ivars. This doesn't appear to impact the lldb test suite, and they will ultimately need to use more abstract access patterns to get ivar offsets from resilient classes (if they aren't already), so I just removed the RemoteAST test cases that tested for class field offsets for now.
We could handle a typealias itself disappearing, but not if the
typealias was okay but the underlying type wasn't. This came up in
real Swift 3/4 mix-and-match code.
rdar://problem/34940079
Rather than storing contextual types in the type witnesses and associated
conformances of NormalProtocolConformance, store only interface types.
@huonw did most of the work here, and @DougGregor patched things up to
complete the change.
If we can't resolve a cross-reference unambiguously, we're supposed to
produce an llvm::Error and let the calling code handle it. However, if
we couldn't even resolve the /type/ of the cross-reference, we would
just crash. Follow the supported error path in that case too -- in
many cases the error can just propagate upwards to something that can
handle it.
rdar://problem/34821187, plus an extra test case from
rdar://problem/35157494. (The latter will be fixed better later, but
meanwhile let's not regress on the crashing part.)
For now these are underscored attributes, i.e. compiler internal attributes:
@_optimize(speed)
@_optimize(size)
@_optimize(none)
Those attributes override the command-line specified optimization mode for a specific function.
The @_optimize(none) attribute is equivalent to the already existing @_semantics("optimize.sil.never") attribute
Rather than inlining generic signatures in a half dozen places throughout
the serialization format, serialize (uniqued) generic signatures with their
own GenericSignatureID. Update various layouts (generic function types,
SIL function types, generic environments, extension cross-references) to
use GenericSignatureID.
Shaves ~187k off the size of Swift.swiftmodule.
When a particular nominal type or extension thereof declares conformance
to a protocol, check whether that type or extension contains any members
that *nearly* match a defaulted requirement (i.e., a requirement that
is satisfied by something in a protocol extension), but didn’t match
for some reason and weren’t used to satisfy any other requirement of
that protocol. It’s intended to catch subtle mistakes where a default
gets picked instead of the intended member.
This is a generalization of the code we’ve had for @objc optional
requirements for a long time.
Fixes rdar://problem/24714887.
Otherwise, a protocol conformance where the witness was a dynamic
property in another module would trigger an assertion while building
the materializeForSet witness, or miscompile and fail at runtime
if asserts are off.
