[PrintAsObjC] Add __attribute__((warn_unused_result)) for non-@discardableResult methods
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* Add `SWIFT_WARN_UNUSED_RESULT` macro to prologue. Evaluates to `__attribute__((warn_unused_result))` where supported. * Emit `SWIFT_WARN_UNUSED_RESULT` attribute in generated ObjC headers for all non-void methods, that don't have an @discardableResult attribute. Attribute is not emitted for initializers. Attribute is also not emitted where the error convention leads to a return value for an otherwise void returning method.
jrose-apple
approved these changes
Dec 10, 2016
| // CHECK-NEXT: - (NSInteger)nonDiscardable:(NSInteger)x SWIFT_WARN_UNUSED_RESULT; | ||
| func nonDiscardable(_ x: Int) -> Int { return x } | ||
| // CHECK-NEXT: - (NSInteger)discardable:(NSInteger)x; | ||
| @discardableResult func discardable(_ x: Int) -> Int { return x } |
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Rather than add a whole new file, I would just stick this in with methods.swift.
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@jrose-apple I didn't find a methods.swift file within the PrintAsObjC tests. I put the test case into classes.swift instead.
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Whoops, yes, that's fine.
Test, that no SWIFT_WARN_UNUSED_RESULT attribute is included in the ObjC representation of a Swift function annotated with @discardableResult.
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@swift-ci Please test macOS |
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@swift-ci Please smoke test Linux |
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Clang importer currently marks methods imported from Objective-C as
@discardableResultbased on theirwarn_unused_resultclang attribute.I would expect
PrintAsObjCto do the same the other way around.This change adds a new
SWIFT_WARN_UNUSED_RESULTmacro to the prologue of the generated interface header files. This macro evaluates to__attribute__((warn_unused_result))where supported.The
SWIFT_WARN_UNUSED_RESULTattribute is applied to the Objective-C representation of all non-void methods, that don't have a @discardableResult attribute. The attribute is not emitted for initializers.It is also not emitted where the error convention leads to a return value for an otherwise void returning method.
Resolves SR-3383.