Code review identified some incorrect UNIMPLEMENTED_CLONEs in DeclAttribute (thank you
Hamish and Rintaro). Fix those, and make sure this can't happen again by checking the type
signatures of clone() in every DeclAttribute subclass.
@lifetime(target: source1, source2...) where target can be any
parameter or 'self'. We cannot have @lifetime attributes with duplicate targets.
Also, update the internal data structures. Previously LifetimeEntry stored
pairwise (target, source) dependencies. Now, LifetimeEntry will store an optional
target descriptor and an array of source descriptors.
In #69257, we modified `ObjCReason` to carry a pointer to the @implementation attribute for the `MemberOfObjCImplementationExtension` kind. This made it mark the @implementation attribute as invalid, suppressing diagnostics from the ObjCImplementationChecker.
However, invalidating the attribute *also* causes it to be skipped by serialization. That isn’t a problem if the diagnostics are errors, since we’ll never emit the serialized module, but #74135 softened these diagnostics to warnings for early adopters.
The upshot was that if Swift emitted one of these warnings when it compiled a library, clients of that library would see the objcImpl extension as a normal extension instead. This would cause various kinds of mischief: ambiguous name lookups because implementations weren’t being excluded, overrides failing because an implementation was `public` instead of `open`, asserts and crashes in SILGen and IRGen because stored properties were found in seemingly normal extensions, etc.
Fix this by setting a separate bit on ObjCImplementationAttr, rather than the invalid bit, and modifying the implementation checker to manually suppress many diagnostics when that bit is set.
Fixes rdar://134730183.
Some requirement machine work
Rename requirement to Value
Rename more things to Value
Fix integer checking for requirement
some docs and parser changes
Minor fixes
Upstreams the necessary changes to compile references to `@backDeployed`
declarations correctly when a `macabi` target triple or a `-target-variant` is
specified.
If a protocol provides a deprecated default implementation for a requirement
that is not deprecated, the compiler should emit a warning so the programmer
can provide an explicit implementation of the requirement. This is helpful
for staging in new protocol requirements that should be implemented in
conforming types.
…for extensions. This change also removes @implementation(CategoryName); you should attach the category name to the @objc attribute instead. And there are small changes to how much checking the compiler will do on an @objc @implementation after the decl checker has discovered a problem with it.
The implementation of `#if hasAttribute(...)` only accepted declaration
attributes. It should also accept type attributes, like `@retroactive`.
Resolves rdar://125195051
Our standard conception of suppressible features assumes we should
always suppress the feature if the compiler doesn't support it.
This presumes that there's no harm in suppressing the feature, and
that's a fine assumption for features that are just adding information
or suppressing new diagnostics. Features that are semantically
relevant, maybe even ABI-breaking, are not a good fit for this,
and so instead of reprinting the decl with the feature suppressed,
we just have to hide the decl entirely. The missing middle here
is that it's sometimes useful to be able to adopt a type change
to an existing declaration, and we'd like older compilers to be
able to use the older version of the declaration. Making a type
change this way is, of course, only really acceptable for
@_alwaysEmitIntoClient declarations; but those represent quite a
few declarations that we'd like to be able to refine the types of.
Rather than trying to come up with heuristics based on
@_alwaysEmitIntoClient or other sources of information, this design
just requires the declaration to opt in with a new attribute,
@_allowFeatureSuppress. When a declaration opts in to suppression
for a conditionally-suppressible feature, the printer uses the
suppression serially-print-with-downgraded-options approach;
otherwise it uses the print-only-if-feature-is-available approach.
When determining whether a declaration should be considered unavailable at
runtime, ignore `@available` attributes for application extension platforms but
continue searching for other `@available` attributes that might still make the
declaration unavailable. This ensures corner cases like these are handled:
```
// Dubious, but allowed
@available(macOS, unavailable)
@available(macOSApplicationExtension, unavailable)
public func doublyUnavailableOnMacOSFunc() {}
// Expresses an uncommon, but valid constraint
@available(macCatalyst, unavailable)
@available(iOSApplicationExtension, unavailable)
public func confusingDiamondAvailabilityInheritanceFunc() {}
```
Use similar scheme as DeclAttribute.
* Create `BridgedTypeAttribute.createSimple()` and
`BridgedTypeAttributes.add()`, instead of
`BridgedTypeAttributes.addSimple()`
* Create `DeclAttributes::createSimple()` to align with `TypeAttribute`
The old TypeAttributes reprsentation wasn't too bad for a small number of
simple attributes. Unfortunately, the number of attributes has grown over
the years by quite a bit, which makes TypeAttributes fairly bulky even at
just a single SourceLoc per attribute. The bigger problem is that we want
to carry more information than that on some of these attributes, which is
all super ad hoc and awkward. And given that we want to do some things
for each attribute we see, like diagnosing unapplied attributes, the linear
data structure does require a fair amount of extra work.
I switched around the checking logic quite a bit in order to try to fit in
with the new representation better. The most significant change here is the
change to how we handle implicit noescape, where now we're passing the
escaping attribute's presence down in the context instead of resetting the
context anytime we see any attributes at all. This should be cleaner overall.
The source range changes around some of the @escaping checking is really a
sort of bugfix --- the existing code was really jumping from the @ sign
all the way past the autoclosure keyword in a way that I'm not sure always
works and is definitely a little unintentional-feeling.
I tried to make the parser logic more consistent around recognizing these
parameter specifiers; it seems better now, at least.
When building the Swift sources of the compiler many instances of the following
warning are emitted:
```
.../swift-project/swift/include/swift/AST/Attr.h:3075:10: warning: cycle detected while resolving 'iterator' in swift_name attribute for 'operator=='
bool operator==(iterator x) const { return x.attr == attr; }
^
```
These warnings were implemented in https://github.com/apple/swift/pull/37940
and they indicate that Swift compiler is failing to import a clang decl because
of circular references. Something about the structure of some operator
declarations in C++ headers triggers this warning. I'm not sure what the
correct long term fix for this is, but in the meantime the build log for the
compiler is getting drowned in these warnings which makes it difficult to
notice and find other diagnostics. Since these declarations are getting dropped
instead of imported, we can simply hide them from the Swift compiler in the
first place by guarding the declarations with `#ifdef __swift__`.
