Support __available__((swift_attr("@Sendable"))) #40170
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This change applies SwiftAttr attributes as soon as possible after creating an instance of a Decl, rather than waiting until the declaration is "finished". That makes sure the attributes can influence the declaration very early in its lifecycle, and in particular, before its conformance table is initialized. Mostly NFC in this commit (other than affecting the order that attributes are printed in), but necessary for future changes in this PR.
...by using `__attribute__((swift_attr("@sendable")))`. `@_nonSendable` will "beat" `@Sendable`, while `@_nonSendable(_assumed)` will not.
This commit also checks if `SwiftAttr` supports `#pragma clang attribute` and, if it does, defines `__SWIFT_ATTR_SUPPORTS_SENDABLE_DECLS` in imported headers so they know they can apply these attributes in an auditing style.
Gives us a place to stuff synthesized declarations for, among other things, imported Clang decls.
An explicit swift_attr("@_nonSendable") will override it (except for ns_error_domain where the type is embedded in another type that's forced to be Sendable), but swift_attr("@_nonSendable(_assumed)") will not.
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With swiftlang/llvm-project#3547 @swift-ci please smoke test |
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With swiftlang/llvm-project#3547 @swift-ci please smoke test |
DougGregor
approved these changes
Nov 19, 2021
| // GetImplicitSendableRequest::evaluate() creates its extension with the | ||
| // attribute's AtLoc, so this is a good way to quickly check if the extension | ||
| // was synthesized for an '@_nonSendable' attribute. | ||
| return ED->getLocFromSource() == nonSendable->AtLoc; |
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This feels a little... brittle... but okay.
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Yeah. :/ I couldn’t think of anything better that would be quick, but maybe I can revisit this; arguably we should just print any unavailable Sendable conformance even if it doesn’t come from @_nonSendable.
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This PR implements most of the sendability auditing support for ClangImporter. Specifically:
__attribute__((swift_attr("@Sendable")))is now allowed on Clang decls, even when it would not be allowed on equivalent Swift decls.@unchecked Sendableconformance if it:@Sendable, but not plain@_nonSendable.enum_extensibility,flag_enum,swift_newtype, orswift_wrapperClang attributes, but not plain@_nonSendable.ns_error_domainClang attribute, regardless of the presence of plain@_nonSendable. (Erroris alwaysSendable, so error codes must also beSendable.)Sendableconformances before printing the contents of a module, and we print the extensions generated by@_nonSendableeven if we would normally skip unavailable or implicit extensions.__SWIFT_ATTR_SUPPORTS_SENDABLE_DECLSto be1.It includes a number of related refactorings:
SynthesizedProtocolAttrs can now create@uncheckedconformances.SynthesizedFileUnits can now be attached to anyFileUnit, not justSourceFile.ClangImporter::Implementation::diagnose()has been overloaded so that, if aHeaderLoc(wrapping aclang::SourceLocationand related info) is passed in place of aSourceLoc, it will emit a diagnostic in the header file. This replaces several lines of boilerplate per use site.Fixes rdar://84431708. It does not implement two things that I will defer to 85569247:
@_nonSendablein parameter position.@Sendable(probably@_unsafeSendablein practice) on completion handler parameters.Some tests will not pass without https://reviews.llvm.org/D112773, which I am in the process of cherry-picking to our clang branches.
This should only cause language behavior changes if you consume headers that include the currently-invalid
__attribute__((swift_attr("@Sendable"))),__attribute__((swift_attr("@_nonSendable"))), or__attribute__((swift_attr("@_nonSendable(_assumed)")))attributes.