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When checking protocol conformances with `@differentiable` requirements, the type checker is supposed to accept omissions of `@differentiable` attributes when there exsits an attribute that covers a superset of the differentiation configuration. This was accidentally regressed in apple/swift#33776 which made the following test case fail to compile. This is fixed by adjusting the witness matching conditions. ```swift // rdar://70348904 reproducer: public protocol P: Differentiable { @differentiable(wrt: self) @differentiable(wrt: (self, x)) func foo(_ x: Float) -> Float } public struct S: P {} extension S { // This had worked until apple/swift#33776. @differentiable(wrt: (self, x)) public func foo(_ x: Float) -> Float { x } } ``` Also fix some suboptimal diagnostics where more information could be shown. Resolves rdar://70348904.
51 lines
2.3 KiB
Swift
51 lines
2.3 KiB
Swift
// Test missing protocol requirement `@differentiable` attribute errors for
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// non-public protocol witnesses, when the protocol conformance is declared in a
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// separate file from witnesses.
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//
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// Implicit `@differentiable` attributes cannot be generated for protocol
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// witnesses when the conformance is declared from a separate file from the
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// witness. Otherwise, compilation of the file containing the conformance
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// creates references to external symbols for implicit `@differentiable`
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// attributes, even though no such symbols exist.
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//
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// Context: https://github.com/apple/swift/pull/29771#issuecomment-585059721
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// Note: `swiftc main.swift other_file.swift` runs three commands:
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// - `swiftc -frontend -primary-file main.swift other_file.swift -o ...`
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// - `swiftc -frontend main.swift -primary-file other_file.swift -o ...`
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// - `/usr/bin/ld ...`
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//
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// `%target-build-swift` performs `swiftc main.swift other_file.swift`, so it is expected to fail (hence `not`).
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// `swiftc -frontend -primary-file main.swift other_file.swift` should fail, so `-verify` is needed.
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// `swiftc -frontend main.swift -primary-file other_file.swift` should succeed, so no need for `-verify`.
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// RUN: %target-swift-frontend -c -verify -primary-file %s %S/Inputs/other_file.swift
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// RUN: %target-swift-frontend -c %s -primary-file %S/Inputs/other_file.swift
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// RUN: not %target-build-swift %s %S/Inputs/other_file.swift
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import _Differentiation
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// Error: conformance is in different file than witnesses.
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// expected-error @+1 {{type 'ConformingStruct' does not conform to protocol 'Protocol1'}}
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extension ConformingStruct: Protocol1 {}
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// No error: conformance is in same file as witnesses.
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extension ConformingStruct: Protocol2 {
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func internalMethod4(_ x: Float) -> Float {
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x
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}
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}
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public final class ConformingStructWithSupersetAttr: Protocol2 {}
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// rdar://70348904: Witness mismatch failure when a matching witness with a *superset* `@differentiable`
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// attribute is specified.
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//
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// Note that public witnesses are required to explicitly specify `@differentiable` attributes except
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// those w.r.t. parameters that have already been covered by an existing `@differentiable` attribute.
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extension ConformingStructWithSupersetAttr {
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// @differentiable(wrt: self) // Omitting this is okay.
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@differentiable
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public func internalMethod4(_ x: Float) -> Float { x }
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}
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