Fix LifetimeDependenceDiagnostics: scoped dependence on a copy #81105
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Handle parameters with no name: foo(_:T)
A small typo meant that scoped dependencies modeled with mark_dependence_addr were not diagnosed.
Diagnose a scoped dependence on an argument that inherits its lifetime as an error: @Lifetime(borrow arg) func reborrowSpan<T>(_ arg: Span<T>) -> Span<T> { arg } @Lifetime(copy span) public func testBorrowInheritedArg<T>(_ span: Span<T>) -> Span<T> { reborrowSpan(span) // expected-error {{lifetime-dependent value escapes its scope}} } Fixes: rdar://146319009 ([nonescapable] enforce borrow constraint narrowing of inherited lifetime)
The implementation previously took advantage of a missing diagnostic. They returned a borrowed Span with a dependency on a copied argument. This illegally promotes the dependency. This is what the author intended to do (the implementation was correct) but the compiler can't know that so the code needs to be explicit about overriding the lifetime.
rdar://150073405 ([SILGen] support synthesized _modify on top of borrowed getters with library evolution)
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Briefly (April 2025), RawSpan._extracting, Span._extracting, and UTF8Span.span returned a borrowed value that depended on a copied argument. Continue to support those interfaces. The implementations were correct but needed an explicit _overrideLifetime.
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Fix LifetimeDependence attribute checking
Handle parameters with no name: foo(_:T)
Fix LifetimeDependenceDiagnostics: handle mark_dependence_addr
A small typo meant that scoped dependencies modeled with mark_dependence_addr
were not diagnosed.
Fix LifetimeDependenceDiagnostics: scoped dependence on a copy
Diagnose a scoped dependence on an argument that inherits its lifetime as an
error:
@Lifetime(borrow arg)
func reborrowSpan(_ arg: Span) -> Span { arg }
@Lifetime(copy span)
public func testBorrowInheritedArg(_ span: Span) -> Span {
reborrowSpan(span) // expected-error {{lifetime-dependent value escapes its scope}}
}
Fixes: rdar://146319009 ([nonescapable] enforce borrow constraint narrowing of inherited lifetime)