This method had a messy contract:
- Setting the diags parameter to nullptr inhibited caching
- The initExpr out parameter could only used if no result
had yet been cached
Let's instead use the request evaluator here.
This assert doesn't consider reference storage types in its predicate.
Look through them since they're not relevant to the type consistency
check it's trying to pick out.
VarPattern is today used to implement both 'let' and 'var' pattern bindings, so
today is already misleading. The reason why the name Var was chosen was done b/c
it is meant to represent a pattern that performs 'variable binding'. Given that
I am going to add a new 'inout' pattern binding to this, it makes sense to
give it now a better fitting name before I make things more confusing.
```
class Generic<T> {
@objc dynamic func method() {}
}
extension Generic {
@_dynamicReplacement(for:method())
func replacement() {}
}
```
The standard mechanism of using Objective-C categories for dynamically
replacing @objc methods in generic classes does not work.
Instead we mark the native entry point as replaceable.
Because this affects all @objc methods in generic classes (whether there
is a replacement or not) by making the native entry point
`[dynamically_replaceable]` (regardless of optimization mode) we guard this by
the -enable-implicit-dynamic flag because we are late in the release cycle.
* Replace isNativeDynamic and isObjcDynamic by calls to shouldUse*Dispatch and
shouldUse*Replacement
This disambiguates between which dispatch method we should use at call
sites and how these methods should implement dynamic function
replacement.
* Don't emit the method entry for @_dynamicReplacement(for:) of generic class
methods
There is not way to call this entry point since we can't generate an
objective-c category for generic classes.
rdar://63679357
The Original Bug
----------------
In ffbfcfa131, we fixed a bug around implicit
value initializers but did not cherry-pick it to 5.3. While investigating a bug
that turned out to be that same bug (no worries!), I noticed that there is
additional code that is "unsafely" correct in this area and that while
ffbfcfa131 is correct in the small, we can expand
on the fix to prevent future bugs.
The Larger Bug
--------------
Here we are still open coding using ManagedValue/Cleanup APIs /without/ a top
level function scope. The code is only correct since we never emit unconditional
cleanups and always manually forward conditional cleanups. If we did not do
either of these things, we would have another instance of this bug, namely a
cleanup that is never actually emitted. So the code on master today is correct,
albeit unsafe, and we already have coverage for this (namely the test case from
ffbfcfa131).
That being said, in general when working with ManagedValue APIs (especially in
utility functions) we assume that we have a scope already created for us by our
caller. So by fixing this issue we are standardizing to safer SILGen invariants.
Building on ffbfcfa131
----------------------------------------------------
This commit builds on the shoulders of ffbfcfa131
by adding the function level scope mentioned in the previous section so that we
are now "safely" correct.
While looking at this I also realized that just using a normal scope when open
coding here may be a bit bugprone for open coding situations like this since:
1. If one just creates a scope in open coding situations, the scope will fire at
end of the c++ function /after/ one has probably emitted a return.
2. Once one has emitted the return, the insertion point will no longer be set
implying =><=.
To avoid this, I created a move only composition type on top of Scope called
AssertingManualScope. This type just asserts in its destructor if the scope it
contains has not been popped yet.
While, one can pop it by ones self, I added an overload of createReturnInst on
SILGenBuilder that also takes an AssertingManualScope and pops it at the
appropriate time.
So now when performing simple open coding tasks, we have the ability to in code
tie together the function level scope to the actual creation of return inst,
simulating the hand-off of lifetimes/resources from caller/callee that often
happens in the epilog of functions.
<rdar://problem/63189210>
If the 'wrappedValue:' parameter is an escaping autoclosure, and a
struct property is marked with that property wrapper, the memberwise
initializer of the struct is now synthesized with an escaping
autoclosure for that property.
If we're emitting a designated constructor inside a constrained extension,
we have to use the correct substitution map for calling the property wrapper
backing initializer.
Factor out the computation of this substitution map and use it consistently.
Fixes <rdar://problem/59245068>.
We had two predicates that were used to determine whether the default
argument for a wrapped property in the memberwise initializer would be
of the wrapper type (e.g., Lazy<Int>) vs. the wrapped type
(Int). Those two predicates could disagree, causing a SILGen assertion
and crash. Collapse the two predicates into one correct one,
fixing rdar://problem/57545381.
Switch most callers to explicit indices. The exceptions lie in things that needs to manipulate the parsed output directly including the Parser and components of the ASTScope. These are included as friend class exceptions.
Since getSpecifier() now kicks off a request instead of always
returning what was previously set, we can't pass a ParamSpecifier
to the ParamDecl constructor anymore. Instead, callers either
call setSpecifier() if the ParamDecl is synthesized, or they
rely on the request, which can compute the specifier in three
specific cases:
- Ordinary parsed parameters get their specifier from the TypeRepr.
- The 'self' parameter's specifier is based on the self access kind.
- Accessor parameters are either the 'newValue' parameter of a
setter, or a cloned subscript parameter.
For closure parameters with inferred types, we still end up
calling setSpecifier() twice, once to set the initial defalut
value and a second time when applying the solution in the
case that we inferred an 'inout' specifier. In practice this
should not be a big problem because expression type checking
walks the AST in a pre-determined order anyway.
Teach SILGen to emit a separate SIL function to capture the
initialization of the backing storage type for a wrapped property
based on the wrapped value. This eliminates manual code expansion at
every use site.
Unfortuantely this commit is bigger than I would like but I couldn't think
of any reasonable ways to split it up.
The general idea here is that capture computation is now done for a
SILDeclRef and not an AnyFunctionRef. This allows SIL to represent the
captures of a default argument generator.
The only place this was used in Decl.h was the failability kind of a
constructor.
I decided to replace this with a boolean isFailable() bit. Now that
we have isImplicitlyUnwrappedOptional(), it seems to make more sense
to not have ConstructorDecl represent redundant information which
might not be internally consistent.
Most callers of getFailability() actually only care if the result is
failable or not; the few callers that care about it being IUO can
check isImplicitlyUnwrappedOptional() as well.
This indicates that the "self" argument to the current function is always dynamically of the exact
static base class type, allowing metadata accesses in IRGen to use the local self metadata to answer
metadata requests for the class type. Set this attribute on allocating entry points of designated
inits, which is one of the most common places where we emit redundant metadata accesses.
When the backing storage of a wrapped property is default-initialized via the
property wrapper type's init(), don't count that as a direct initialization
of the backing storage for the purposes of constructing the memberwise
initializer. Instead, treat this case the same as if there were no initializer,
keying the form of the memberwise initializer off the presence of
init(initialValue:).
The determination of whether a property is memberwise-initialized is
somewhat confused for properties that have synthesized backing properties.
Some clients (Sema/Index) want to see the declared properties, while others
(SILGen) want to see the backing stored properties. Add a flag to
`VarDecl::isMemberwiseInitialized()` to capture this variation.
This utility was defined in Sema, used in Sema and Index, declared in
two headers, and semi- copy-pasted into SILGen. Pull it into
VarDecl::isMemberwiseInitialized() and use it consistently.
This is a large patch; I couldn't split it up further while still
keeping things working. There are four things being changed at
once here:
- Places that call SILType::isAddressOnly()/isLoadable() now call
the SILFunction overload and not the SILModule one.
- SILFunction's overloads of getTypeLowering() and getLoweredType()
now pass the function's resilience expansion down, instead of
hardcoding ResilienceExpansion::Minimal.
- Various other places with '// FIXME: Expansion' now use a better
resilience expansion.
- A few tests were updated to reflect SILGen's improved code
generation, and some new tests are added to cover more code paths
that previously were uncovered and only manifested themselves as
standard library build failures while I was working on this change.
If the initializer witnesses a protocol requirement, the protocol witness
thunk references the allocating entry point directly, since it has no
vtable entry. For this reason we must use alloc_ref_dynamic and not
alloc_ref to ensure the right type of instance is allocated.
Fixes <rdar://problem/49560721>, <https://bugs.swift.org/browse/SR-10285>.
The initialization of an instance property that has an attached
property delegate involves the initial value written on the property
declaration, the implicit memberwise initializer, and the default
arguments to the implicit memberwise initializer. Implement SILGen
support for each of these cases.
There is a small semantic change to the creation of the implicit
memberwise initializer due to SE-0242 (default arguments for the
memberwise initializer). Specifically, the memberwise initializer will
use the original property type for the parameter to memberwise
initializer when either of the following is true:
- The corresponding property has an initial value specified with the
`=` syntax, e.g., `@Lazy var i = 17`, or
- The corresponding property has no initial value, but the property
delegate type has an `init(initialValue:)`.
The specific case that changed is when a property has an initial value
specified as a direct initialization of the delegate *and* the
property delegate type has an `init(initialValue:)`, e.g.,
```swift
struct X {
@Lazy(closure: { ... })
var i: Int
}
```
Previously, this would have synthesized an initializer:
```swift
init(i: Int = ???) { ... }
```
However, there is no way for the initialization specified within the
declaration of i to be expressed via the default argument. Now, it
synthesizes an initializer:
```swift
init(i: Lazy<Int> = Lazy(closure: { ... }))
```
The initializer associated with a lazy property should not be executed
directly, because it is subsumed by code synthesized into the
getter. Generalize the terminology here so we can re-use this path for
property delegate initialization.
Since 'decl' was already a StructDecl, 'decl->getDeclContext()' was
giving us a non-generic module scope context.
Fixes <https://bugs.swift.org/browse/SR-10075>.
The bulk of the changes are to SILGenApply. As we must now evaluate the
payload ArgumentSource to an RValue, we follow the example of subscripts
and lie to the argument emitter. This evaluates arguments at +1 which
can lead to slightly worse codegen at -Onone.
When emitting initialization code for stored properties that have
default values within an initializer in an extension containing a
same-type-to-concrete constraint, we can end up with conformances
involving concrete types. Look for that conformance within the module
of the initializer rather than asserting.
Fixes rdar://problem/47723747.
This undoes some of Joe's work in 8665342 to add a guarantee: if an
@objc convenience initializer only calls other @objc initializers that
eventually call a designated initializer, it won't result in an extra
allocation. While Objective-C /allows/ returning a different object
from an initializer than the allocation you were given, doing so
doesn't play well with some very hairy implementation details of
compiled nib files (or NSCoding archives with cyclic references in
general).
This guarantee only applies to
(1) calling `self.init`
(2) where the delegated-to initializer is @objc
because convenience initializers must do dynamic dispatch when they
delegate, and Swift only stores allocating entry points for
initializers in a class's vtable. To dynamically find an initializing
entry point, ObjC dispatch must be used instead.
(It's worth noting that this patch does NOT check that the calling
initializer is a convenience initializer when deciding whether to use
ObjC dispatch for `self.init`. If we ever add peer delegation to
designated initializers, which is totally a valid feature, that should
use static dispatch and therefore should not go through objc_msgSend.)
This change doesn't /always/ result in fewer allocations; if the
delegated-to initializer ends up returning a different object after
all, the original allocation was wasted. Objective-C has the same
problem (one of the reasons why factory methods exist for things like
NSNumber and NSArray).
We do still get most of the benefits of Joe's original change. In
particular, vtables only ever contain allocating initializer entry
points, never the initializing ones, and never /both/ (which was a
thing that could happen with 'required' before).
rdar://problem/46823518
Dynamic replacements are currently written in extensions as
extension ExtendedType {
@_dynamicReplacement(for: replacedFun())
func replacement() { }
}
The runtime implementation allows an implementation in the future where
dynamic replacements are gather in a scope and can be dynamically
enabled and disabled.
For example:
dynamic_extension_scope CollectionOfReplacements {
extension ExtentedType {
func replacedFun() {}
}
extension ExtentedType2 {
func replacedFun() {}
}
}
CollectionOfReplacements.enable()
CollectionOfReplacements.disable()
